Greetings from India. I own the same combination of pre and power amp.I wanted to know of a way to effectively run 6ohms speakers with this setup. The “SENTINEL” speakers, which came along with the setup are put in series and are 8ohms. I, along with a friend, changed them to parallel. The sound has opened up. The highs are a lot more airy and bass tighter. But the speakers distort and go squeaky on highs if played even with the volume at 10 p.m.. is there a way to set this problem right?
Welcome to Audio Room, good to meet another owner of this fine set!
Unfortunately I do not know the Sentinel speakers, I have only seen one photo of them. I understand that the Sentinels are 2 way speakers with one woofer and two tweeters. I’m guessing you changed internal connection of drivers inside the speaker (maybe tweeters were originally in series and you changed that to parallel?), and that changed the speaker’s nominal impedance from 8 to 6 ohms?
I do know that Enbee ZX80 drives 6 ohm and 4 ohm speakers without any problems, also at high volume. I used Enbee with both types. I do not think the amp is the problem in your case.
I’m afraid your problem might result either impedance dropping much lower than the nominal value at higher volume levels, or from pushing too much power through the tweeters in the current parallel connection. If you have a power meter, you could try connecting it before one of the tweeters and see how much power it receives at the same volume level setting when connected in series and then in parallel. Without being able to test it, I would advise against using these speakers in their current connection. If you’re pushing more power than you should through the tweeters, the will be more audible at low volume, but will get squeeky and distort at high volume, and eventually you will damage them. Maybe try experimenting with different tweeters instead? Peerless drivers are very efficient.
Thank you so much for the reply. Yes the tweeters have been put in parallel. The original X overs have been changed too. When I run the pair with my PULZ RB250, the sound does not get squeaky. Though the highs have opened up beautifully I must confess. As I mentioned, I have 2 pairs of these speakers. The preamp has the provision for 2 power amps. So I have connected two amps to it. The speaker have 2 seven inch drivers and 4 tweeter in one setup. My friend suggested that we take 4 tweeters out and instead put 2 silk dome tweeters. This would take the added workload off the tweeters too (the tweeters being full range, basically paper cones which operate like that). I understand that this would increase the impedance and mellow the HIGHS too. You think this would be a good solution?
Yes, that’s what I would try to do. Best if you use tweeters with higher power rating than the original paper tweeters, and use something that can handle fairly low crossover frequency. If the original tweeters are fullrange paper drivers, they might start quite low. If there’s still too much power going to tweeters, maybe try an L-pad? I can’t be more specific without knowing exact specifications of Sentinel and their drivers/crossover.
Yes I intend using Peerless drivers. My complete setup is of Indian make. Well… They are Indian too now. But I need to find silk domes with an impedance of 8 ohms right? If the drivers are 4 ohms and I have to put them in series so that the nominal impedance does not go down too low? But will that defeat the whole purpose as in series the twitters will produce lower sound?
If you put tweeters in series, their impedance will add: two 8 ohm tweeters connected in series will have a nominal impedance of 16 ohms. If you put them in parallel, impedance drops: two 8 ohm tweeters connected in parallel will have a nominal impedance of 4 ohms. And yes, if you connect them in series, they will produce lower volume. But it might still be enough, you’d have to try and see. Peerless tweeters are efficient and quite “aggressive”. I would try with a single Peerless tweeter, too.
had a few problems setting them right. The 2 way xover was changes to 3 way. Finally set the speakers to 8.2 ohms in series parallel and it works great now. Though you already know, but if anyone else would read this in future, GREAT SOUNDSTAGE. I am a sucker for old stuff but when the equipment is good to compete with the new ones, the joy is even more. Read your other posts in other forums. It seems you keep a lot of vintage stuff too. But thank you so much for the help.
greetings from India
Glad to hear that you’ve managed to solve this! Did you use Peerless tweeters, or did you keep the originals, only in 3-way setup?
I love vintage (and simply older) equipment too, some of it sounds really great and if you don’t care about facilities like remote control you can build an amazing system for relatively little money. I guess this Enbee doesn’t qualify as vintage yet, but it will soon.
By the way, does your ZX1 pre also have background noise when the tone controls are on?
Anyway, if you want to share a photo of your system, let us know. We will be happy to add it to our gallery.
Yes I used peerless silk domes. I have 2 sets of speakers and decided to operate on one pair first. They have become 3 way now. As I mentioned earlier, the xover has been changed. The original design had a 2 way xover. The impedance rests at 8.2 ohms. Yes the preamp does give a miniscule buzz when the EQS are switched on. But that gets garbed in the sound of music. . Unfortunately they need to be used at times, specially with phono, if the mastering is not too great. Infact my amp catches radio signals too if i use a slightly longer speaker wire. I live in Mumbai and unfortunately the weather here is hot, humid, sultry and wet, hence not conducive for electronics. To maintain these vintage items does take a lot of doing here. But I would hang on to these forever. You had written about changing the opamps, did you experiment with that? I am due to visit my friend in a day or two to discuss the same. Though I hope I get the ones you mentioned here in India to start with. By the way, I know Mr. Nakra personally and have spent a lot of time with him on my visits to Delhi. He is a genius with radios.
It’s the same with my EQ, the noise is there, but minor and not a problem when the music is on. I haven’t tried replacing the op-amps yet, maybe I’ll make it my winter project. In case you try first, let me know the results. I mentioned TL071CP because it’s commonly suggested as a substitute for 741 op-amp, and it is cheap and available, so you should get it without problems. There probably are other options, too. If you’re in contact with Mr. Nakra, maybe he has suggestions?
I have not noticed any problems with radio interference, but the FM signal is not very strong in my area.
I am starting with switching the EQ and volume pod sequence. As it does not need any physical change and only a change in the circuit, it would be easily achieved. I think that should make a considerable difference. Changing the opamps is a lengthy process which requires time. Unfortunately we do not have winters in Mumbai so can’t designate a time for the project. But the EQ and vol. pod change is being made as I write to you. Let me see what difference it makes. I’ll keep you posted.
Great, do let me know! If you can make a photo of new connection of the volume pot and EQ (if it’s visible at all), please send it to me too. Theoretically it should remove most of the background noise at low and mid volume (and EQ switching noise), but there’s always a risk that non-attenuated input signal from loud source can overload the EQ, so play a loud CD and listen for distortion during loud passages. Good luck!
And yes, i’ll post some good pictures soon. Looking at the ones you have put here, this setup could walk the ramp.
It made no difference at all. I guess changing from 741s to TL071CP might make a difference. But another thing to look out for is the leakage from a few components at times. This is something that I encountered myself. The preamp does make a noise when the EQs are switched on, but remains quiet thereafter. As it is I heard nothing when I switched it to CD mode, my only problem was phono stage, but that seems to have gone too. I think the volume pod and EQ switch would have mattered more had it been an integrated model, which would have meant others disturbances too, with the power amp in the same unit. But all in all Rafael, the noise hardly comes in the way of music, if all the leakages are tightened. My only problem is that I can’t experiment with the preamplifier for very long as this is the only preamp unit I have and hence the only way to listen to vinyls. Haha so the ball is in your court, with winters arriving soon.
Thanks for the report! No difference is strange, theoretically if the volume pot is the last thing in the circuit, it should attenuate any background noise too. Well, we will see after I experiment with mine. I have EQ switching noise (quite loud 1st time I use the EQ switch after turning on the preamp, much better afterwards – this probably comes from the switch itself or a capacitor near the switch) and minor white noise in the background when the EQ is on – that’s from 741s.
Also, some preamps, especially their phono stages but not only, pick up noise from power amp’s transformer when they are directly on top or below the power amp due to insufficient shielding. I have 2 preamps that do that, a Harman/Kardon and a small MBO, they have to have at least 10 cm distance from the power amp, if they are closer they start to hum. But I did not experienced this problem with ZX1.
One more thing I wanted to ask you: when you look at photos of my pre and power amp, are there any differences between my set and yours? I’m interested primarily in output transistors, filtering capacitors etc. It looks like my units have original parts, but I would like to confirm that.
Yes, if they are all made in Holland then they are all genuine. That is what Mr. Nakra used. But I would corraborate with the fact that distance between the pre and power might make a difference. If I turn up the volume, there is a hmm in the system in the phono stage. Though it remains only in the phone stage. Not in CD or tape. There is a current in the body too, which I do not know how to irradicate. Though I must tell you that I used my Klipsch SUB with it with great results, which is a big audiophile NO NO, but fine. I think i’ll try the whole process again. Though I do not know, but if NAD and other amps do not have a hmm in the phono stage then this could be rectified too. Mr. Nakra would have known this problem for sure.
Rafael tell me, if you crank up the volume in phono stage, do you get slight hum at 12 o clock, which increases from there on? The hum and hiss in my system was way too loud, so I put a thin metal sheet over the phono circuit, though the hum has not completely gone, it has reduced for sure. Is there something that I could do to better the situation?
(PS:- It”s been long since I heard from you.)
I was on vacation, and recently I focused more on developing the Polish language version of Audio Room.
I have not noticed particular hum from the Enbee’s phono stage, but I wouldn’t be surprised if it were there. I will check next time I use Enbee and let you know. Most amps have it, after all phono input has much more gain than line inputs, which also translates to amplifying the amp’s internal hum and noise, and any interference the phono stage or the turntable cart might pick up. I don’t know how you placed your power amp and preamp, if one is directly on top of the other putting some distance between them could help. It did work in another system in which I had this problem.
Also, computers are a common source of hum, so if you have a computer connected in the same room, you can try do disconnect it from mains and see if there’s any change.
Quadral Germany will repair bandtweeters! I know, it’s not around the corner. But if you really love these speakers, they’re worth it.
I’ve heard about that, and I agree they’re worth repairing, especially that this tweeter model is not manufactured anymore and I think old stock ran out several years ago. But mine were incomplete, one tweeter was missing the magnet, the other had the enclosure completely gutted (no ribbon, no magnet), and someone had put crappy plastic Philips tweeters inside the enclosures to have some sound coming out of them. They were beyond repair.
I tried keeping the pre and power apart but that did not help. The hum starts at 12 o clock. Though it does not really interfere with the sound. Tell me, have you tried putting a tube preamp with a solid state amp? Is there a change in sound? There is one Mr. Viren Bakshi here who makes tube setups by the name of LYRITA AUDIO. A very respected name in the field and popular in the audiophile circles. He suggested that the phono stage will improve vastly if this combination is used.
I don’t think I’ve ever listened to this set with volume control set at 12 o’clock. The room I use Enbee in is simply not large enough for that level. In any case, slight phono stage hum in an amp at that level is quite normal, and like you said, it does not really interfere with listening to music.
I have not tried a combination with tube pre. I am tempted sometimes, but I stick to solid state for now. I’m afraid tubes will be a Pandora’s box for me, so I try not to open it. But I think phono stage is the one part of the Enbee setup that could be improved, at least with some records and cartridges it would benefit from some more body/warmth, and tubes could provide that. I did use a different sounding external solid state phono stage connected to ZX1 line input with good results (it was a TEC TC760LC ), smoother and softer highs, more bass and fuller midrange.
I looked at Mr. Viren Bakshi’s website, he makes a phono preamplifier. if you know someone who owns one, maybe you could borrow it and try? I think for tubes I would try a phono stage connected to Enbee ZX1 pre first, and not a full tube pre amp connected to ZX80 power amp. I do not feel the need to improve Enbee ZX1 line level inputs.
pandora’s box is just about the best way to put it. Even I feel that if I jump on to the tube band wagon, then finding the best quality tubes and from the most reliable company and so on would drive me nuts. It would take me far away from the reason which helps me pay for all the equipment I own. A phono tube pre is exactly what was on my mind too. Unfortunately borrowing one here in my city is out of question as LYRITA AUDIO has a very select market and all the references given to me by Mr. Bakshi, own integrated amps. Size of the equipment has also started to come into play now. The music rack is getting loftier and so is my wife’s frown. The tube preamp that LYRITA offers is pretty big in size. I was thinking of a few smaller options online but haven’t found anything worth while as yet. The fact that almost all the brands have contrasting reviews only adds to your confusion. India is still not open to hifi markets and companies like MARANTZ, ONKYO and DENON sell their lower rung products in heaps here. Any perticular external phono stage preamp that you would suggest?
I am also from India, I have handled earlier amplifiers from ENBEE when i was in college (1979 thereabouts). Those days there were 2 models viz; EA-50B and the Touch- 200. There were also speakers available with these amps which were not that great, how ever the amplifiers were pieces of art. When matched with a 12 inch BOLTON and metal dome tweeters, the sound was out of the world. The EA-50 B was rated at 50 watts RMS per channel and The Touch -200 , 100 watts RMS per channel. 2N3055 with split supply in quasi complimentary, there was even a preset to adjust the DC offset in the amplifier output.
The Touch 200 had a very neat piece of technology, the selector switches were replaced with relays, that operated on a finger touch. There were disc shaped electrodes on the facia for each of the switch functions. One could select the required function (input select, loudness etc) by touching the required disc with one finger tip and a reference disc with another finger tip.
My friend was the retailer for ENBEE in Kochi, and he had met Nishi Nakara. From what I gather, Nishi Nakara catered to a very small section of Audiophiles and was known for his build quality and of course the sound. He apparently did not have an aggressive marketing policy to promote the products, and sold mostly by word of mouth. A pity since in his prime he was right up there.. along with another famous audio guru of indian descent.. amar bose.
I have a pair of quadral amun phonologue gold. Happy to sell them.
Well, I hope my review helps 🙂
My experience is Amuns (and other Quadrals with ribbon tweeters) sell quite easily if you put them on auction with bidding starting relatively low, say an equivalent of $100. Then they normally go up to $250-$500, depending on condition, luck and location.
I have 8.1’s non SE. Not sure what SE is. I either have a bad speaker or cross over. When I send a test tone from my A/V receiver I don’t hear it until I tap on the Kevlar speaker. Then it works. Even when I listen to music, I have a 5 channel option on my Marantz SR8000 receiver. So all my speaker should come on. It will not work until there is some low bass then it will work. Seems weird, that is why I am thinking a bad cap or something. Just wondering if you had some experience with these.
Frank, the symptoms you describe are typical for a bad contact/connection. With a bad cap normally you would have a problem all the time, it wouldn’t be intermittent (and go away when you tap the speaker or feed a signal with lower bass). It could be on the crossover, midwoofer’s connector or in the driver itself (less likely). I would start with checking if the speaker wires from your receiver and the bi-wire jumpers are secured tightly (unless you’ve done that already). Then have a look at the crossover, check the connector screws on the inside and reflow all solder joints. If that doesn’t help remove the midwoofer and check the wire connections to it. I don’t remember if the wires are soldered to the midwoofer or connected with – if they have bobby pins check if they are connected securely, if they are soldered, reflow. If you’ve done all that and the problem remains, try swapping the woofers between speakers – if the problem follows the woofer, the woofer needs to be repaired or replaced. If it stays with the speaker, recheck all connections and start checking continuity of crossover parts. Hope that helps.
Looks like when they heat up they start to work. Bad, voice coil winding, or component.
I would check all connections and solder joints just in case before you start buying replacement parts.
One more important question I forgot to ask, and I should start with that: when the speaker does not work, is only the woofer silent, or both woofer and tweeter? If both are silent, this would suggest that the problem is NOT in the speaker. The paths are separate for each driver from the connectors on the back of the speaker all the way to each driver. If neither driver works, and then they both start working when you play a louder signal or play music for a longer time, this indicates that the problem is in the receiver (or the wire between the receiver and speaker, but that’s less likely).
But if one driver plays and the other is silent, then the problem is in the speaker.
It’s not the speakers. Either A/V receiver or cable. Probably receiver, as it warms up it start to work. I have both Wharfedale 8.1 regular and SE. The SE’s look to have a more realistic wood grain to them. They look like real wood. I think everything else is the same.
I swapped with a new speaker cab it behaved the same, forgot to mention that.
In that case, the symptoms would indicate a bad joint or dirty relay in your receiver. Normally it would be quite easy to repair, but AV receivers are more complicated with more channels and features packed inside. Troubleshooting can take a while, and access to components inside is probably not easy. You could start with making sure all the connectors inside are firmly placed (especially the white ribbons) and, if you can see relays, tapping them to see it sound appears in the problematic channel when you do that. This would have to be done with the receiver on and working and cover off, so be very careful, easy to damage something else this way. If you don’t feel safe doing that, or simply don’t have a lot of time and patience – take it to a repair shop.
You’re right about the relationship between Superscope and Marantz. Those were Marantz output sections. You should try to use 0.22 ohm resistors in your 1270 and set the bias to compensate. That will probably then sound exactly like a Marantz 2235.
The Superscope receivers I have repaired all had silver faceplates, never seen a black one. Could be the difference between Canadian and US models I guess. They were good sets though, no doubt. It’s too bad that most receivers are being damaged by the hoard of flippers who “recap” receivers. That and the prices are just stupid these days. What people need to do is find a good audio technician who used to work on Marantz receivers and have it properly restored. It would be nice to see them saved from the hackers iron!
Well, I just set a higher bias (mV) to account for .5 ohm resistors, the end result should be the same as using .22 ohm resistors and setting a lower bias, right?
The black face is gorgeous on this one. I used to have a Marantz 2226 in black as well, that one looked good too (but the Superscope loos better IMO). Now I’m trying to score an older “princess pink” Superscope receiver, but unfortunately flippers have caught on and the prices have gone up on those. I do have a Supersope A-260 amp, it has some pink lights too.
Luckily most people around here have the “if it ain’t broke, don’t fix it” approach, so most classic Marantzes I see have original parts. But I agree that finding a decent technician for anything is not easy these days, let alone Marantz. I should know, both my quad Marantz receivers (4240 and 4400) needed some repairs.
Tengo un r1270 está óptimo pero honestamente no se como conectarle las bocinas ya que no tengo las originales, solo cuento con 1 par de 16 omhs, 1 par de 8 omhs y 1 par de 12 omhs (los Subwofer). Ya que trae 2 salidas de principal speakers, 2 salidas de remote. Aparte abajo trae salidas de quadraphase…. Ayuda xfavor
You connect one pair of speakers to MAIN.
You connect the other pair of speakers to REMOTE – then they play exactly the same sound as the MAIN speakers.
Or you connect the other pair of speakers to QUADRAPHASE – then they play a bit altered sound to create fake surround effect.
You don’t connect the subwoofer at all, unless you can connect the MAIN speakers through your subwoofer (it is possible with some subwoofers).
Conecta un par de bocinas a MAIN.
Conecta el otro par de bocinas a REMOTE; luego, reproducirán exactamente el mismo sonido que los bocinas PRINCIPALES (MAIN).
O conecta el otro par de bocinas a QUADRAPHASE, luego reproducen un sonido ligeramente alterado para crear un efecto quasi-surround.
No conecta el subwoofer en absoluto, a menos que pueda conectar los bocinas PRINCIPALES (MAIN) a través de su subwoofer (es posible con algunos subwoofers).
Could anyone tell me what is the sensitivity and frequency response for Quadral T 50 20/LT 300 A tweeter driver?
Unfortunately I couldn’t find specs for these tweeter, I don’t thing Quadral published this. The only available information can be deduced from the specs of speakers in which these tweeters were installed. Quadral set crossover point at 4 kHz for all speakers with these tweeters, and they stated that the top limit as 40 kHz, so the tweeter’s frequency range should be at least 4000-40000 Hz, but tolerance is not stated either. Sensitivity is not published anywhere. Maybe try to contact Quadral, they might have technical data for these tweeters in their archives.
Was wondering if you could tell me the value of the cap that’s on the back of the tuning meter. My friend’s R1220 isn’t working. Think the cap may be bad. Thanks.
Unfortunately I can’t look at my Superscope R-1270 at the moment. But this cap should be the same as in corresponding Marantz designs, and that is: 100uF 10V electrolytic cap.
“the volume control potentiometer that has separate adjustments for left and right channel (rather than common volume adjustment for both channels and a separate balance pot). ”
Glad I read this review because I had somehow never noticed this before! I couldn’t figure out why I couldn’t get my setup properly balanced! However, this amp is still extremely loud when connected to my turntable. No idea what’s going on there, but at least it’s properly balanced now.
Glad our review was helpful Ted!
Not sure why the amp is extremely loud with your turntable, its PHONO input sensitivity is fairly standard (2.5 mV 47 kOhm). The sound from turntable connected to PHONO input is usually a bit quieter sound than from other sources (like CD, tuner) connected to line input (for example AUX).
Here are some of the possible reasons:
1. Your turntable has an MM cartridge with a very high output. Some carts are louder than average. If that’s the case, either live with it or change your current cart to something quieter (with lower output).
2. Your turntable has a different type of cartridge, for example a piezoelectric crystal or ceramic cartridge. If that’s the case, you should connect it to a different input (AUX, TAPE, CD, TUNER – any of these will work). PHONO input is only for turntables with MM (moving magnet) cartridges.
3. Your turntable has a built-in phono stage (phono pre-amp) or is connected to your Denon amp via a separate phono stage. Some turntables (particularly modern ones) have built-in phono stages, also many people use external phono stages like NAD PP1 or TEC TC760LC. If that’s the case, you should also use a different input.
If in addition to extremely loud sound you also have excessive bass from your turntable, that would indicate reason 2 or 3.
If you give me more details (exact turntable model, cartridge name and model, if anything is connected between your turntable and amp) I can check specifications and maybe figure out what’s going on in your setup.
Hey! Thanks for reaching out.
I’ve gone over some of this and I can’t quite put it together, but here is my current setup:
MCS 6700 turntable with a fairly standard AT95E Audio-Technica cartridge. It’s an older turntable so I don’t believe it has any built in pre-amp and I’m connecting it through the phono input on the receiver and running a pair of Polk TSi100 speakers. Just for the sake of experimenting I’ve tried plugging it into a non-phono jack on the receiver and it was whisper quiet. The turntable (phono) and my iPod (aux) are nonetheless both aggressively loud. I usually run them at a volume of “2” out of “40.”
What’s strange is that I have a Technics SA-R477 receiver that I sometimes use (preferring the Denon as it’s a better fit for my super-basic setup as you note in your review) and the turntable/iPod have totally normal output.
I’ve read that this receiver has a bit more oomph than others and I’m thinking about just buying/building some RCA line level attenuators to drag the system down a couple of dB. I’m not sure if you have any additional insights, but I nonetheless still really appreciate the review you wrote (helped me rediscover how great this receiver is) and the information you have posted above.
OK, it’s not your turntable or cart. MCS 6700 does not appear to have a built in pre-amp and AT95E is a standard MM cartridge, so everything’s connected properly.
One note, Denon PMA-250 is an amp, not a receiver. Receivers have built in radio tuners. Your Technics SA-R477 is a receiver.
Your Technics receiver could have a different input sensitivity, but I suspect the difference lies simply in the volume potentiometer characteristics. Potentiometers have different attenuation curves, which is one of the reasons why some amps get loud faster than others while having similar rated power. I don’t remember my PMA-250s getting loud too fast, but my speakers are not very efficient.
RCA line level attenuators would do the trick, but I would advise against using them with a turntable. A better solution would be to plug attenuators in the tape loop. This way thy will attenuate a line-level signal (as opposed to phono-level signal, which is much weaker and more susceptible to loss, distortion and interference), and one pair will work for both phono and aux inputs. And you can easily put them in/take them out of the signal path by switching the TAPE MONITOR button. Actually a regular stereo volume potentiometer in the tape loop would work perfectly. I use this solution in amps that have volume level imbalance at low volume levels (and unfortunately many do).
I bought a EA 50B with associated speakers in 1978 and still have them. It has given me wonderful service all these years. Recently the right channel volume has started varying on its own. Could not figure out the reason. Need help.
The EA 50B was an integrated amp, right? With amps from that period, the cause for such behaviour are very often oxidizing contacts in switches, potentiometers and possibly speaker relay. Especially if the balance between left and right channel is restored ad high volume level, dirty contacts are the main suspects. If that is the case, thorough cleaning should remedy the situation. We are planning to add a section on basic amp maintenance in the future, but for now there’s a very good guide here:
The basic idea is to spray the cleaning agent into each potentiometer and switch so that it reaches the contact inside, and then work each of them (press/flip switches and turn potentiometers many times) to wipe off the oxides and dirt. The cleaning agent mentioned in the above guide is DeOxit, which is available in the US, more difficult to find in Europe, not sure about other parts of the world. If you can’t find it, get a product that’s available in your area and is called something like “electrical contact cleaner”, “electrical switch cleaner”, “potentiometer cleaner”. DO NOT use products like WD40, you will destroy your amplifier.
If cleaning potentiometers, switches and possibly speaker relay does not help, the cause could be some components, most likely capacitors in the preamp section (but it could be a transistor or resistor too), deteriorating due to age. The amp is almost 40 years old after all. The only solution in this case is to replace bad components, you will probably need an electronics technician services for that.
If the problem only affects the PHONO input, the most likely problem is a bad component in the phono preamp. Again, bad component needs to be replaced.
But first, check interconnect cables that connect sound sources to your amp. It could be as simple as bad cable.
Hope that helps you a bit. By the way, I couldn’t find photos of EA 50B anywhere. If you could take a few photos and send it to me, I would be very interested to see what this amplifier looks like, and with your permission maybe post them on our website. you can email me at firstname.lastname@example.org
Thanks for the prompt reply and valuable inputs. I will try and get all that done. I am located in Pune, India.
No problem. We’re in Warsaw, Poland, so unfortunately we won’t be able to physically assist you, only share some hints on how to tackle this issue.
EA 50 B is an integrated amp. I am using a dvd player through the aux input. The interconnect cables are good and connections are firm. I will email the photos.
I got your photos. I don’t see anything obviously suspicious, but any of these smaller blue capacitors could be bad at this point. In any case, the amp certainly does need cleaning, so definitely start with that. First remove as much dust and dirt as possible from the inside of the amp using a small paint brush, hair should not be too hard to avoid destroying connections. Be careful around the VRs – the four horseshoe shaped components that are on two circuit boards, best if you don’t touch them. They regulate voltages in the power amp, they shouldn’t be moved even slightly without measurement equipment properly connected.
You can also blow dust out, but do not vacuum clean (too risky).
I can see corrosion on metal parts, which means that contacts in pots and switches are certainly oxidized too. Once you removed dust and dirt from the amp, you should clean all switches (I can see that there are a lot of them) except the power switch and probably the switch on the rear panel (that’s a voltage selector right?) by spraying contact cleaning agent inside each switch, letting it stay there for e few minutes and then working (pressing or flopping) the switch many times. The potentiometers that I can see are slider type. If you clean them, best to use the cleaning solution called Fader Lube. If you don’t find that, use what you have, but in very small amounts.
I checked, DeOxit is available in India on Ubuy, but it seems expensive. This thread lists a few alternatives you can find in India, they will probably be cheaper:
There’s also something called Protochem Electrical Contact Cleaner, it’s much cheaper than DeOxit and should be OK too.
Best if you find something with a long straw applicator, that it allow you to reach the switches located deeper witout having to dismantle you amp.
Having looked at the photos, I see that the amp has PRE OUT jacks for connecting an external power amplifier. If you have or can borrow one (or powered speakers), you could connect it to your Enbee EA-50B and test the sound. If the problems with the right channel volume persist also with an external power amplifier or powered speakers, the problem with your Enbee is somewhere in its preamplifier section. If the problems with the right channel volume do not occur in this configuration, that would mean that the Enbee’s power amplifier section has issues. This would help search for bad components, if cleaning does not help.
I would like to create a selector-switch box for 3 amplifiers to my set of speakers.
I’m using the speaker outputs A and B on every amplifier.
The set of speakers includes : 2 columns (high-medium), 2 bookshelf speakers (med-low) and one subwoofer.
Using the same principle that you’ve described for 2 amplifiers and 1 pair of speakers,
– do you think this would be safe,
– would you recommend it,
– what would be the schema to make it.
Very best regards.
Adding switches in the signal path can always degrade the sound a bit. But with switches of this type any change in sound should be minor or even inaudible. My way of switching is safe for both amps and speakers, so it can be used also in your scenario.
To accommodate 3 amps and 2 pairs of speakers you can daisy-chain 3 switches made according to the same principle as my switch. Or actually 2 switches like mine to switch between the amps and one cheap, ready-made speaker selector, because switching between speakers is a less sensitive issue and you can have both pairs of speakers playing at the same time and, unlike amps, they can have common ground. Unless one of your amps does not tolerate that, in that case it is better to use my (safer) switch.
So we have:
Amp A, Amp B and Amp C
Speakers A and Speakers B
Switch 1, switch 2, switch 3
Remember that my switches can work both ways, this means that they can have either 2 inputs and 1 output or 1 input and 2 outputs.
Connection would go like this:
1. Switch 1: 2 inputs, 1 output. Amp A and Amp B are connected to the inputs of switch 1. It selects between Amp A and Amp B.
2. Switch 2: 2 inputs, 1 output. Amp C and the output of switch 1 are connected to the inputs of switch 2. It selects between Amp C and whichever amp has been selected with switch 1 (Amp A or Amp B).
3. Switch 3: 1 input, 2 outputs (this one can be ready made if all your amps can handle common ground and more than one set of speakers connected at the same time). The output of switch 2 is connected to the input of switch 3. The outputs of switch 3 are connected to Speakers A and Speakers B.
With the above system, switches 1 and to select amp A, B or C (only one at the time). Switches 1 and 2 MUST be like the one I used in my project. Switch 3 selects speakers A and/or B. This one can allow to select both speakers and have common ground if ALL your amps can handle that. If any of your amps can’t handle that, use the safe switch (like mine).
That covers amps and stereo speakers. To accommodate subwoofer I would have to know what kind of subwoofer you’re using and how it is connected to each of your amps. If it’s a passive or active “pass through” subwoofer that you connect to the speaker outputs of an amp, and then connect stereo speakers to the subwoofer – you can connect it the same way to one set of outputs of switch 3. If it has a different connection method, I’d have to know the details.
Hope that helps,
Great info, but I’ve got an even more complicated setup. I have 4 different 5.1 home theatre amps in my garage. At the moment, only one is connected. I have 3 sets of speakers connected plus a powered subwoofer. These amps were all thrift store purchases but were all pretty good quality, Denon, Onkyo, Marantz, etc… ranging from 250 watts to 400 watts each. The speakers are one in each corner, and 2 halfway down the wall, and the subs are in the center. They are spaced around the room alternating left and right speakers, so no matter where you stand in the room you hear the music in stereo. I want to be able to switch between amps just to see which one sounds best. Am I going to need 4-way switches or what?
That is a lot of amps and speakers. To my knowledge, there are no reasonably priced mechanical switches that would allow to switch between two 6 channel amps, and you have four. You would need 12PDT switches, which do exist but are very expensive.
I can think of 2 solutions.
1. The complicated way: you build several switches and maybe coupling bars for levers that would allow to flip 3 switches in one move. 3 switches like mine used together allow to switch between all channels of two 6 channel amps (switch 1 for front channels, switch 2 for rear channels, switch 3 for center and sub). Then, you can daisy-chain switches: you connect an additional switch to each of the inputs of the switch that is connected directly to speakers. If my calculations are correct, with a total of 9 switches like mine you can compare four 6 channel amps. That is a lot of switching and a lot of switches to build, wire etc. I would probably choose death.
2. The easy way: you build one switch like mine and compare front channels only (stereo mode). If front channels sound good, chances are the rest is at least acceptable. If front channels sound bad, the amp will not sound good in 5.1 mode either. By comparing two amps at a time, you can quite quickly figure out which amp sounds best.
Your particular unit probably needs to be recapped. Notice how this article is the only one on the internet that doesn’t praise the sound quality of this amp.
That is possible. Although, while this amp has not been recapped, nor have most of the amps we’ve used and we’ve never heard bad caps affect mids and soundstage like that. In most cases bad caps affect bass first (especially PS caps) – not the case here. In those cases that soundstage suffered due to bad caps (usually problems with caps in the signal path, mainly preamp section), high frequencies were always also affected, actually more than mids. Not the case here (highs were good), and this particular amp dis not exhibit any other issues that could indicate problems with capacitors either. This alone of course does not mean that the problem is not caused by caps – but makes it less likely.
Also, the problem I have with the sound of this unit is actually similar to what I’ve heard from many other Technics amps from that and a bit later period. Almost all of them had something strange going on in the midrange. The later Technics amps from mid-1980s to 1990s were even worse (flat across the range, not just in the mids). I’m talking about budget models of course. I’ve heard good-sounding Technics amps too, but most were closer to top of the line and much more expensive.
Also note that people who use and comment on amps of this type (middle of the line vintage) 1. often use vintage speakers of questionable sound quality that hide the amp’s deficiencies behind their own ones – and those speakers are often mid-centric, and 2. often focus more on bass and treble than on mids. This Technics handles bass very well, and highs also well, so I’m not surprised that many people like it. Even the owner of the unit we tested likes it too and has no complaints about its sound.
But if we have an opportunity to test another SU-7700, we will certainly do that to confirm whether this is the sound signature of this model or rather a problem with that particular unit.
I have a slightly different question and want to be certain I have it right.
2 receivers/amps, 2 pairs of speakers Utilizing Channels A & B.
The first receiver is Surround-Using Channels A & B, + Klipsch Subwoofer.
The second receiver, Marantz 2252, Using Channels A & B (same speakers), but no subwoofer.
Thank you so much for the knowledge you’ve already imparted.
Glad my article is helpful!
Now to your specific situation. I understand that the subwoofer is not important because you only use it with the surround receiver and you only need to connect speakers A and B to two receivers. There are two possible scenarios:
1. You use either speakers A or speakers B (but never both at the same time) with each receiver
2. You use both speakers A and speakers B at the same time with each receiver
I understand that your situation is the second scenario.
Also, one of your amps is a stereo receiver (the same signal goes to speakers A and B) and the other amp is a surround receiver (different signal goes to speakers A, different to speakers B). That is also important. That means that even if you ALWAYS use both speakers A and B, they cannot be connected to the switch in parallel, because only the stereo receiver uses a parallel connection. The surround receivers actually works as two separate amps (front speakers amp and rear speakers amp). I understand that in the case of the surround receiver speakers are connected to front and rear outputs, and not to front A and front B outputs (that would be a very different connection and actually similar to using a regular stereo amp).
In that case, the best solution is to use two switchers like the one I described. One switch switches speakers A, the other switches speakers B. Unfortunately there are no simple, sturdy and cheap mechanical toggle switches (that I can find) that would allow to switch a total of 8 separate signal lines (and that’s how many you get with 4 speakers), which is why you need a separate switch for each pair of speakers. It’s not a big problem, you just flip 2 switches instead of one. But it does mean two times the work, materials and time needed to build the switcher.
The two switches and corresponding speaker binding posts can be fitted into one enclosure, obviously it would need to be larger.
This solution (2 separate switches for speakers A and speakers B) will work perfectly fine in other scenarios, for example with 2 stereo amps that use speakers A and B, or with a stereo amp and a surround receiver where the speakers are connected to front A and front B outputs of the surround receiver (as opposed to its front and rear speaker outputs). But in some cases a simpler solution would suffice.
Hope that helps. Let me know if you have any more questions and good luck!
Thanks for this post
Managed to put a switchbox together this afternoon and It works a treat, no more ‘protect’ mode.
Total cost here in Aus, including enclosure was around $17.
Very happy with the result.
Glad my post could help. I’m curious to see your switchbox, send me a photo if you can. My email is in the ‘Contact Us’ tab.
So do I understand correctly that you were using a different switchbox before and it was sending your amp into protect mode? What sort of switchbox was it?
I am currently building one of these and had a question. Could this used to use one turntable with two amps subbing RCA jacks? I see no reason why not do you?
Sure, but it’s overkill. You can also use a cheap ($2) AV switch for that purpose. Search for “AV RCA Switch Selector Box”. Common ground between channels is not a problem with turntables, and you can use the 3rd RCA socket to connect and switch the grounding wire.
AV RCA Switch Selectors can have resistors inside, which degrade signal quality.
I disassembled 2 cheap passive AV switchboxes that I happened to have at home and I did not find any resistors or other components inside that would alter the signal, just sockets, a PCB with tracks and a switch. The quality of components if as poor as can be expected, but there are no wires, so it should primarily affect the switch durability, not signal quality. At least it shouldn’t do any more harm than an average quality cable would.
I used one of these switches for a turntable in my decent (but not hi end) system without any problems or audible signal loss. I used the video socket to connect (and switch) turntable ground. But whether such a switch degrades the signal could vary depending on the quality of the audio system (there could be an audible difference with a hi end system – just like with better and worse quality cables).
Active switchboxes are a different story, in my experience they do degrade sound and have their own background noise.
Of course, toggle switches can also be used for this purpose. A 4PDT switch has the right number of connections (L+, R+, common ground, turntable ground). Common ground is not a problem with turntables in most cases. But i still think building a switchbox with a toggle switch is overkill for switching the source-amp line (including turntables), considering that a simple AV switchbox does the job and it’s very cheap. Unless it doesn’t work (or causes signal degradation) in your system.
BTW, resistors should not degrade signal quality (unless they’re poor quality themselves), they should simply make the signal weaker, quieter. That, of course, is not preferable in the case of signal from a turntable, which is very weak to begin with.
I am trying to get parts for this idea but I wondered if I can just buy
a speaker switch and modify it?
If I open this unit and modify it following your instructions for a
single switch and remove the second switch this would be the cheapest
and most convenient solution for me. What do you think?
Appreciate any help. Thanks.
Buying the speaker switchbox you mention might be an option but:
– that speaker switchbox costs almost exactly the amount we paid for all parts (including the enclosure) of the switchbox in our article, since then we’ve built another switchbox that was 30% cheaper because we’ve found cheaper sockets; of course that depends on the cost of parts in your area but you would still have to buy some parts you will need to make the conversion: at least a 4PDT switch and probably some wires;
– you would still have a lot of work to do, you would have to replace the two switches that are there now with the switch we recommend (a 4PDT switch), and fitting a 4PDT switch in an opening left after one of those flat cradle switches might be difficult and it might turn out that you can’t fit a 4PDT switch with screws for wires (it’s quite large and might not fit in this enclosure) and have to use a smaller switch that you have to solder wires to – soldering 12 wires is more tedious;
– you will probably still have to rewire the speaker wire connectors: this switchbox probably has common ground (they usually do) which is OK if you switch between speakers, but should be avoided if you want to switch between amps;
– you would still end up with a switchbox that has poor quality wire connectors (these spring-type connectors in the back – we do not recommend them, they are a problem if you use a wire that’s too thick or too thin for them and they break more easily than even the cheapest screw-type connectors).
That’s the potential problems I can think of from the top of my head. In short: yes, converting that speaker switchbox should be doable, but it might not be easier or cheaper than building a switchbox from scratch. Buying parts could be cheaper depending on the prices in your area, conversion of that speaker switchbox might involve a bit less work or not, depending on its internal wiring and how easy or difficult fitting a 4PDT switch would be.
Hope this helps. Good luck on your project. If you have more questions, drop me an email, and let me know when you’re done, I’ll be curious to see a photo of you switchbox (whether you build it or convert the one you’ve linked).
New to researching, purchasing Audio. I just took early retirement and have enjoyed searching, finding and buying such treasures.
I bought a SuperScope today at a sale for $20. A light is out, maybe 2, on the left side when looking at tge faceplate.
I hooked it up to the closest speakers sitting idle and it sounds surprisingly good. Listening to Steely Dan at the moment through old Pioneers.
The seller was awrsome, gave me an old Sherwood Tuner, l believe made in Chicago.
If anyone knows the Specs on the R-340 Receiver l sure would appreciate any help..
Also purchased a Marantz 2226e, and havent fpund any info on the “e” model.
Tuner works good
Gary, congratulations on your purchase! Superscope R-340 is a cute receiver, on my “to get” list (pink lights!). And $20 is a great price for a decent vintage receiver that works, even a low power one like the R-340.
Superscope R340 is from 1973, it is rated 10W per channel at 8 ohms (RMS), its peak (music) power is 15W per channel. You’ll find other specs in the file I emailed you. BTW, 10 WPC is more than enough for listening at home, unless you have a really big room or like to listen very loud. But better avoid boosting bass or using loudness at higher volume levels.
For dial and meter lights you will need 8V 250mA fuse lamps (the same ones as in Marantz receivers). My advice is to use regular lamps (not LEDs – my personal preference, regular lamps look better to me) and to replace all lamps, not just the ones that are out. You can keep the old ones that work as spares. Stereo light is probably a 8V (less likely 6.3V) 40mA bi pin lamp. DO NOT USE a stronger lamp (for example 60mA) – it could damage the tuner. If that lamp works, best leave it alone.
Marantz 2226e is simply a European version of 2226. The same specs apply and the service manual is the same. The only differences are that the “e” has mains voltage selector on the rear panel and a low filter switch on the front panel, the non-“e” (US model) does not have a voltage selector and instead of low filter it has a 25μS setting is for altering the FM de-emphasis. Low filter is more useful, especially if you have a turntable.
If wired in reverse, will any of this product accomplish the same as your build?
https://www.amazon.com/Stereo-Speaker-Selector-Switcher-Combiner/dp/B00CZNXKRA – I feel like this one might be the closest device to yours.
This one seems a bit different https://www.monoprice.com/product?p_id=8231&gclid=Cj0KCQjw9NbdBRCwARIsAPLsnFY3irQDDTwoTY2nCMGMrJqjC3JZGhr5XVCGtgZnLWA7odr7z3nH4ecaAkCBEALw_wcB
If any of the above would work, could you please let me know advantages/disadvantages vs. yours and Beresford TC-7220? I really appreciate your insight. A tube amp just arrived and I’m looking forward to hooking it all up.
I’m afraid the first 4 options would not work One reason is that it’s quite likely they all have common ground. It’s not certain, but it’s simply much easier and cheaper to build a selector with common ground and it is not a problem if it is is a speaker selector. But can be a problem if it is an amp selector. More importantly, they have the A+B selection possibility, which is what you select if you want to fry your amps (it would connect amps to each other and fry output transistors).
The fifth option (Monoprice) is theoretically designed to work with 2 amps. But I would have to see its internal wiring to confirm that it does not have common ground. Also, putting an attenuator (volume control) in line is a good way to degrade the sound, so I would not do that. On top of that, it has impedance matching (also bad, unless your amp can’t handle a 4 ohm load and you have to use that.
In short, I would not use any of these switchboxes to switch between amps.
Also, many tube amps should not work (be turned on) without load (speakers connected). Make sure that yours can before you use it with a switchbox – it effectively disconnects speakers.
Hey! Thank you so much for this article. It’s very well written, clear and concise. Very helpful. I had the same problem and just like you I just put the headphones away for a long time and always felt terrible about it. However, with this article, I have some hope again. My only question is where did you find the 2.5 mm mono jack sockets? I have been looking for them and can’t find ones that would fit. I would really appreciate if you can shed some light on where I can purchase them. Thank you!
I did not use a mono socket, it’s a stereo socket (actually a 4-pole socket). I simply used the 2 pins corresponding to the right poles of the mono plug. I bought these sockets locally, but they are quite easy to find, search for 2.5 mm SMD Headphone Jack Socket. They are very cheap, so my advice is to get 3-4 different sockets and use the one that fits best.
I’ve just found such a switchbox: https://www.amazon.com/Amplifier-Receiver-Speakers-Selector-Switcher/dp/B0796KGVXT/ref=sr_1_4?s=electronics&ie=UTF8&qid=1540735524&sr=1-4&keywords=amplifier+switcher&dpID=414UiX3FHhL&preST=_SX300_QL70_&dpSrc=srch
It’s price is quite reasonable but I don’t know what it has inside 😉 What do you think it’s worth to buy?
The price is reasonable compared to the Beresford switchbox. Separate switching of L and R channels is less convenient (you need to flip 2 switches instead of one), but works just as well. The big question is whether it switches ground as well (like our switch) or has common ground (bad). Unfortunately I don’t see an answer to this in the description or in Q&A. I think there is a good chance that the ground is switched in this one, but I can’t be sure without testing it. Try asking the seller, maybe you’ll get a clear answer. But even if he confirms that ground is also switched, I would still test it before using.
It’s confirmed that this product is a break before make. It also has resistors, which I believe would make it safe for my tube amp. Would you confirm?
That’s what it looks like in the picture posted by a reviewer on Amazon.
This is exactly what I want to do with a Pioneer VSX-AX10, thanks for the post, excellent job you did, very pro.
That Pioneer is a big one! I have an Onkyo HTR with a dead sound processor chip that will probably also end up as a power amp if I manage to locate the audio signal entry points to the main amp.
Great article! I’m definitely going to try this build for A/B testing amps.
Here’s another similar but much more complex problem. I’ve got a display wall of all of the early Mac tubes (49-70) which don’t have the issue of risking damage without load. My dream is to be able to select an amp (or set of mono blocks) to listen to on my main system from a central wall mounted switch box. The perfect scenario would be to control the power from that switch as well so that as I switched one, it would power it up and cut the power to the previous. (11 total- 8 stereo pairs, 3 stereo amps). Any thoughts?
Now that is a challenge.
Your scenario would require a rather complex and heavy duty system, you’re talking about switching power (2 poles), line level input signal (4 poles) and speaker level output signal (4 poles), a total of 10 poles at the same time, break-before-make, between 11 devices. And ideally it would allow to switch from any to any device (say from amp no. 5 to amp no. 8, not just 1 to 2, 2 to 3 and so on). I’d say a passive, mechanical system is out of the question unless you are a mechanical engineering professor with a group of eager students who would jump at the project. An active, relay-based system maybe? That would also require serious skills, but seems easier to design and implement. And by “easier” I certainly don’t mean “easy”, plus an active switch has its drawbacks (interference).
I think I would try to do something very old-school instead, a manual solution. Imagine a 10-pin plug (for example a Chinch Jones connector, like P310CCT) and a board with eleven 10-contact sockets (like S310RP). You would have to manually pull the plug from one socket and put it into another, but it would allow to switch all ten connections in one move, break-before-make. One potential problem is that the power connectors would be right next to signal connectors, so there’s interference potential, but if you use shielded cables, that’s only at the connectors. And you’d have to use plugs that fit in sockets only in one position. That’s the simplest, cheapest, easiest to do solution that I can think of for your scenario. I know it’s very 19th century, but it might just do the trick.
Hi i have a ENBEE ZX1 and XZ80 music system with four speakers. I want to sell it need some help UI n case anyone wants to buy. Its in real Good condition.
Hi Col. Amandeep, I am interested in buying it if you still have it. Please contact me at email@example.com
I have a ENBEE ZX1 and ENBEE ZX80 music system with speakers, am interested in selling it can you help me. My mob no is 7018673649. Regards
Were based in Europe (Poland to be exact), so I’m afraid we won’t be of much help if you want to sell locally, and if you want to sell internationally you can effectively achieve the same (or better) result by simply putting it on ebay, for example.
What we can do is pin our Facebook post about Enbee to the top of the page for a week or two and allow you to post your sale offer in the comments. Who know, maybe there will be some takers, but bear in mind that they might be from other countries. This is the link to the post: https://www.facebook.com/audioroom/posts/1306692026047259 Let us know if this is something that would help. Or you can simply put your sale offer in the comment and once it’s there, we’ll move the post to the top of the page.
Also, since this page is publicly available, I’m not sure if sharing your phone number here is a good idea. Let me know if you’d like it removed from the above comment. If you want to leave it for people who might be interested in buying your Enbee set, I’d ad a country calling code (+91 if you’re in India).
I have many receivers, CD players, tape decks, turntables, speakers etc… Need to be able to switch between them.
For example I want Auxiliary #2 on Receiver #3 through speakers #5. you get the idea.
I could build something but do you know if there is any gear that does this already. I don’t want any modifications to sound or tone I just want to switch between the components. Switch between Receivers, speakers, Aux, and phono.
I’m not aware of any single device that would do all that. I imagine you’d need a network of switches, and they should be passive if you care about sound quality. If you can accept some hum, you can use something like Pro.2 SP 200 between line level sources and amps/receivers: http://audio-room.net/pro-2-sp-200-source-amplifier-switch-gallery/
For turntables, I strongly recommend a passive switch (active switches are likely to add hum/noise that would be amplified by the phono stage, resulting in a very high noise level). For speakers, you can daisy-chain a few switches like the one I’ve built to switch between amps (remember that break-before-make and no common ground are crucial here), and then connect their output to a commercial speakers switch to switch between several pairs of speakers (these switches can have common ground and allow multiple connections at the same time unless you’re using tube amps, class D amps or ones that can’t handle low impedance speakers). But bear in mind that the more switches you add to the signal patch, the more sound quality you will lose. One switch usually makes no difference, several switches could audibly degrade sound.
there are some vintage equipment that can do this.
Sony SB-5335, Pioneer U-24 Onkyo u30
Sony System Selector MKII, Technics Model 103,
No all of them, the Pioneer and Onkyo selectors are not designed to switch amps and I wouldn’t try to use them for that. The Sony, Technics and Sansui should be fine but I’d check for common ground just in case. There are also Aiwa and JVC system selectors with amp switching function. The main problems with all of them: quite rare, very expensive.
OK, my question is pretty simple but I want to make sure. I want to run my old Marantz and Phillips turn table thru the same speakers as The Denon powers the CD player, tape deck and dvd player. So the the same switch box as you describe function for this set-up?
Assuming that your “old Marantz” and “The Denon” are amplifiers or receivers, the answer is yes.
My superscope 1240 has speaker “thump” or crack on powering on and off. Suspect the capacitors in the speaker line. Happens in mono & stereo.
Advice needed on which caps specifically to replace.
Speaker “thump” while turning on/off is normal with vintage amps and receivers, and newer ones that don’t have relays too for that matter, I have an Exposure amp that has quite a loud thump. Here;s a quote from its manual: “Our amplifiers exhibit turn-on and turn-off transients, heard as “pops” or “thumps” through the loudspeakers. These transients can cause no damage to the loudspeakers, are indicative of normal operation, and such are no cause for alarm.”
As far as the cracking sound goes, power switch would be my first suspect.
Do you think this principle would work on the pre amp stage. I have a computer generating music supplying a mixer to broadcast to hospitals. We broadcast 24/7 but being volunteers there are many hours when the mixer could be powered down and the music signal could go direct to webcast, but it is the switching that bothers me. Have you any suggestions?
Yes, and you’d need a much simpler switch for that. Assuming you use RCA connectors, search for “AV switch”.
Hi, I have 2 receivers: one is an old receiver, Luxman R-1050, which can handle 4 speakers and Onkyo HT-RC270, which supports maybe 11 speakers. I’m looking for a selector switch that can only accept 4 speakers for 2 receivers. My question is it okay to buy a speaker selector switch that only supports 4 speakers leaving the rest of the Onkyo speakers unconnected? By the way, I like the selector switch you made and posted on the internet. If I can use that selector switch, I would like to have one of those – depend on how much. Thanks!
You basically need 2 switches like the one we made to support 2 pairs of speakers (each switch would handle 1 pair of speakers). Yes, you can leave the rest of the Onkyo speakers unconnected (or connected to Onkyo only). We could make such switches for you, contact me at firstname.lastname@example.org for details.
Diamond 8.1 Pro Actives here….
I want to know where the fudge this article was when I researched these? Thanks Google (P.O.S> company), maybe give us what we search for and not what you want us to see…I wanna punc h the azzhole in the fkn throat who owns Google… And ever Communist pig working there.
Now on to these horrible speakers….
100 watt LOL, yeah right….. Not clearly… Muddy trash, one speaker just like the authors, 1 tweet plays lower than other….
I would never buy these, even at $20 a pair, some may say the amp and enclosure is worth more than that, sure, but why use a small enclosure and weak amp when you could spend a little more and be way happier.
I have built $100 pairs which would blow these out of the water in any instance with any music….
Of course those drivers I used are no longer made (just like all good things, some douche in an office desides whats best and fails…
When you’re doing A/B test to compare 2 sets of amp using the switch connected to the same set of speakers, are you using the same source (eg CD player) ?
I am a little confused because if you are using the same source, you would have to manually switch interconnects between the source and amp every time you toggle the switch ( to select your desired amp), am I right?
I guess what I am asking is if one were to do an A/B test on amplifiers with the same source and speakers, using your switch would still require the tester to manually switch interconnects (linking source to amp), right?
Thanks a lot for taking the time to answer my query.
We use one source connected to both amplifiers at the same time via Y splitters. It’s not ideal because splitters may slightly affect sound, but even if they do, they affect it the same way for both amps. We use identical cables (same brand, model, length) for connections to both amps and we switch these cables mid-test to exclude any differences between cables.
hi am interested to buy it
It’s not ours to sell, the amp belongs to a reader, we only serviced and tested it.
I do not know whether it’s just me or if everybody else encountering
issues with your blog. It looks like some of the written text within your content are running off the screen. Can somebody
else please provide feedback and let me know if
this is happening to them too? This could be a problem with my browser because I’ve had this happen previously.
We haven’t seen this problem in any of the browsers we tried. Which browser do you use and on what device?
Thanks for the reply.
When you say Y -splitters, do you mean a switch? something like this: shorturl.at/mFLX5?
I just came across this project for two amps to one pair of speakers switch box which I’m interested in building.
I have a question.
Is the contact points inside the 4PDT switch equivalent to a 16AWG cable ? That is, is there sufficient
contact area at each point to match the cross sectional area of say a 16AWG cable ?
I admit I don’t have enough electronics knowledge to know whether my question is relevant.
With one amp and one pair of speakers there would a pair of speaker cables going directly from the
amplifier output jacks to the speaker jacks.
With this switch box there would be suitably short cables (16AWG or other) from the jacks of the two
amps going to the respective input jacks in the box. Wires from each set of input jacks will then connect
respectively to each side of the 4PDT switch, then the four common (middle pins) of the switch will
connect to the output jacks in the box from which the main speaker cables will be connected to the
So I’m wondering if with all these connection points there is sufficient contact area at each position
within the switch suitable for the guage of cable being used.
If I build this box to use, only one amplifier will be powered on at any time. It will be to select either
a high powered or low powered tube amp.
Yes, the contact points of the 4PDT toggle switch we used in our switch box can accomodate a 16AWG cable. As far as I recall, we used that or 15AWG. It wasn’t easy to catch it safely with these smallish screws, but doable.
You got the connections and internal wiring right, that’s exactly how it should be connected.
If you use this type of switch box with tube amps then yes, to be on the safe side only one amp should be powered on at any time and it should be selected (with the switch box) before you turn it on to ensure that the amp is not on without load.
Thank you for your response Rafal. I decided to go with a simpler but less convenient solution.
You see, I only need to switch my amplifiers a few times per year. I use my high power tube amp
mostly during the cold season and my low power amp during the hot summer months which lasts
less than four months here in Toronto, Canada.
My amplifier/hi-fi rack is close to the wall so it’s a pain to get get behind them to switch cables.
I made a simple box to which I screwed a suitable piece of 2mm thick aluminum panel drilled
with holes for the jacks.
The cables from each amp are connected to the respective jacks for amp-A and amp-B via a bare
wire connection in the holes for this in each jack. The speaker cables are then plugged in to each
set of jacks depending on which amp is being used. All I have to do now is move the little box from
under the rack to switch the speaker cables. Less convenient than with a switch but still a suitable
solution in my case. I should also mention that this involves only one break in the cables from the
amps to the speakers.
Regarding my original question, I now see that I wasn’t too clear in how I put the question.
By mentioning contacts I wasn’t referring to the screw terminals on the switch to witch the wires
are fastened. I was thinking more of the contacts made inside the switch when the toggle lever is
thrown to one side or the other to select either amp-A or amp-B.
Are these contacts sufficiently robust enough to accomodate the electrical signal from the amp
to the speaker. I’m not sure how this works as my electronics knowledge is very limlted.
Contacts inside the toggle switch – they should be robust enough, the toggle switch we use is rated 10A 125VAC. That’s much more than speaker protection fuses in most amps.
So, your solution is basically a simple patch panel. Tried that too, but it’s inconvenient if you switch often (I do). If you only use it a few times a year – sure, it’s much easier to build.
Sorry Rafal but I just realized my shortened link does not work.
Hope this one does:
Is this what you meant by “splitter”?
No, I do not mean a switch. I mean a non-switching splitter that splits the audio signal from the source and sends it to both amps at the same time. A simple RCA Y splitter looks like this: https://ae01.alicdn.com/kf/H6f0d6bc384d34f68acb17d4ae196734aT/2pcs-1-Male-to-2-Female-RCA-Cable-Adapter-Connector-RCA-Y-Splitter-Audio-Video-Plug.jpg
Thank-you very much Rafal.
Your guidance is much appreciated!
Now that I know what you meant by a Y-splitter, I just want to make sure that, if the source is a CD player, then I would need to have one Y-splitter for each of the RCA outputs (Left and Right). The left Y-Splitter should be connected to both the left inputs of Amp A and Amp B.
The right Y-Splitter should be connected the both the right inputs of Amp A and Amp B, is that correct?
Thanks in advanced.
Exactly. Note that in some rare cases this connection (source connected in parallel to 2 amps) could cause sound degradation. So before doing an A/B test, make sure that the sound from source is not affected. The easiest way to do that by ear is to connect the source to both amps via Y splitters, play through one of the amps, and disconnect only cables going from the Y splitters to the other amp while listening. If the sound doesn’t change, it’s all good. Then do the same for the other amp.
There’s definitely something wrong with the unit you have. This is a well built amplifier especially when looking at the circuit design at a technical level. The sound stage is precise. You need to test the units THD using proper equipment at a specific wattage to determine if it is within spec. Does the unit in question have the original matched transistors? As previously stated your capacitors are probably defective in the unit under review. These amplifiers sound best with the period correct linear phase speakers Technics SB-X50. These units were designed to deliver perfect phase matched frequencies with exquisite care taken in designing the internal crossover.
Like I wrote before – this could be the case, but the sound of this amp (specifically flat midrange) was actually similar to other Technics amps from that period that I had the opportunity to use. So either this is how Technics amps from that period sound and it’s not the sound we like, or Technics amps simply don’t age well compared to what we see in amps from other manufacturers. Either way, not a purchase I would recommend.
We do not have the Technics SB-X50 speakers you mentioned, so we could not test with those. If it’s like you say and the amp was designed with those speakers in mind, maybe it would sound better with them. I see that they have horn-loaded midrange drivers and additionally adjustment pots for both midrange drivers and tweeters, so it looks like a lot of design thought went to getting as much mids as possible. But I’d be wary of any amp designed for a particular set of speakers.
A key design objective of the engineers when designing this equipment was to reproduce the original musical waveform in its entirety virtually perfectly (0.08% THD and usually better depending on the frequency measured, 40w 8ohm load driving both channels produced 0.02% THD, 20khz 0.02% 20hz 0.0075%). I initially was skeptical and used lab equipment at my university to validate the results (Project from my studies). The current mirror loading design in the differential amplifier first stage produces minimal transient distortion during power fluctuations. As a result it effectively controls noise levels during moments requiring increased current loads. This is congruent with your perceptive observations of good high and low frequency performance. It must be noted that best results were obtained when paired with the Technics SB-X50 speakers. The amplifier needs to be paired with output drivers of decent quality to achieve good results as is the case of any piece of equipment. Ignoring all subjective opinions the amplifier does an elegant job of maintaining musical fidelity and in this rare case the engineers at Panasonic deserve praise.
If I ever get my hands on another SU-7700, I will definitely test it to see how it compares. But I do reserve the right to my subjective opinion until then; after all, all reviews are subjective and ours are no exception 🙂
In any case, the speakers we use for testing are of good quality, and we always use more than one pair to exclude possible synergy issues. I admit that most of the speakers we use could be a more difficult load for an amp than Technics SB-X50 (judging by specs).
Hi there! Happy to read about the 2230b.
I purchased one a few years ago and I am very happy with the sound. At the time of purchase, It was sounding good and all functions working, so I decided not to send it for cleaning or revision. It turns out that now the ON switch sometimes gets stuck on and sometimes fails to make the “click” that holds it turned on. We use it every single day, so I think the button is a bit tired. You mentioned above that there is no damage in leaving it on, since we plug it into a on/off power strip – I will try that, for sure. But if you have any othe ideas on this, I would be glad to know.
Also, looking inside, it appears to be in need of cleaning. The metal board below the components is not as bright as the pictures I see in this post…. in fact this is worrying me a bit. Do you think this is sometthing I could do myself or should I take it to a specialized service? Do you have recommendation of a basic cleaning tutorial for me to follow?
Greetings from São Paulo
Power switch is a fairly common problem in these receivers (vintage receivers in general, not just Marantz and not just 2230b). Turning it on and off with a power strip is a good workaround. Sometimes the power switch can be repaired, in most cases it is easier and better to simply replace it. It is fairly easy to find the part on ebay, but it should be replaced by an experienced technician.
As far as cleaning goes, a little dust inside won’t hurt your receiver, but you can clean it with a soft, long brush. I prefer to clean the surfaces dry if possible, if necessary you can also use isopropyl alcohol. Using a vacuum cleaner is not a good idea (high risk of accidental damage). Cleaning controls is a bit more tricky as it requires good access to each potentiometer and switch (usually at least some disassembly is required) and using a contact cleaner. There are many turtorial videos on youtube, so have a look to see what it involves. If you don’t feel confident that you’ll be able to do it yourself, best leave it to a technician. Of course cleaning controls makes sense only if they cause problems (for example they are noisy or cause intermittent sound).
I have exactly the same spec and would like to have it cleaned / serviced.
We could probably do this for you (but you would have to let us know what kind of servicing it needs – is it just normal maintenance or are there any malfunctions?), but shipment costs to Poland and back to you could be prohibitive depending on your location.
Hi, there. I don’ t know if you’re still updating this helpful thread. I take seriously your warning about using this switch with a tube amp and the problem of a “no load” condition. I’m guessing there simply isn’t any workaround, which is unfortunate. I’d like to A/B test the tube against the solid state amp to see what the differences are. Thanks!
I’d say do some research first. No load is a problem for many, but not all tube amps, so try to check which group your amp belongs to.
If your amp does have to have a load to be operated safely (or this information is not available), a possible workaround is to use a dummy load – a resistor connected in parallel to the amp’s speaker outputs. The resistance value of the resistor depends on your amp’s recommended speaker impedance. As far as power rating goes – higher is better, best to match or exceed your amp’s rated power per channel, definitely do not use anything below 10W.
If you do that, first check whether (and how) this dummy load affects the sound. It might have little or no effect (for example volume drop that can be easily corrected, you have to match volume of both amps anyway), but it might also alter the sound enough to make any A/B test pointless.
BTW, our experience is that if you learn to listen for certain aspects of sound (like colouration, soundstage, clarity, detail, PRaT, etc.), use recordings you know very well and fairly neutral-sounding speakers, you can compare amps without a switchbox (with breaks needed to change connections) and still catch most differences between amps – as long as they are not very similar. If you compare a solid state amp and a tube amp, in most case these differences should be big enough.
Do you know of a design that switches a dummy load into the speaker output the amplifier that has been deselected but is out of the output pathway when the amplifier is selected?
It would have to cross-switch: between [A1 to S, A2 to DL] and [A1 to DL, A2 to S]. Unfortunately I haven’t seen a simple, cheap, single switch that could do that for 4 lines (which doesn’t mean it doesn’t exist, but I can’t recommend one). You can actually do that quite easily with two switches like the one I described above, but you’d have to remember to flip bot switches at the same time. Or, if your amp has connectors for 2 sets of speakers, you can add dummy loads to the second set of connectors and switch to those when the amp is disconnected from speakers.
But from what I read, you can use a resistor with higher resistance (32 ohm or even 100 ohm) as a dummy load. This way it serves it’s purpose when the speakers are disconnected but it’s “invisible” (does not affect sound) when the speakers are connected.
Nice information, I had experienced the difference.
I went through your review. Anyways I own a Technics 7700ii for the last four months and something, I think it is a great sounding amplifier. I am not technically inclined to speak of this equipment in technical detail but I know what I am hearing and it sounds pretty good. I have several other amplifiers with me including a Vintage Sansui 310, Denon PMA-300V, Technics SU-Z15, Pioneer SA-500A, and I used to own few others in the past but this 7700II is something. It has ample bass and all other frequencies sound good too. I have them hooked up to my favorite pair of speakers which is “Altec Lansing High FIdelity 95” and they pair very well.
Maybe it could be a wrong pairing if it sounds bad.
Thanks for your comment! Good pairing is always crucial! My understanding is that SU-7700II is a bit different from SU-7700, namely there were changes to preamp’s power supply. That could affect the sound a bit. And then there’s the matter of personal preferences and hearing differences. There’s a long list of reasons why we might be critical of an amp, but you like it. And in this case, our advice is: always go with what YOUR ears tell you, the most important thing is that your amp sounds good to you.
Hello, I love reading your blog. It is really very impressive. I want to leave a comment in your support. Carry on with good continuation. Best of luck for your blogging efforts.
I’ve just found this review, 5yrs late!! Haha, never mind.
Spot on as far as I’m concerned. I found the same sound quality when I bought a pair stupidly on magazine reviews. They only lasted 6 months in my system before I went back to my 1984 Castle Clyde speakers. Thank goodness I never moved them on before getting the 8.1’s. Ok the Castle’s are larger size wise but they have an open sound that the Diamonds couldn’t even hint at. Good at low volume too it has to be said. I can’t see me ever selling the Clydes. I had the usual foam rot on the bass drivers but the replacements I got direct from Castle at the time have rubber surrounds, so should be good for a while yet.
Funnily enough I also tried Tannoy Mercury M1’s and found these veiled in the treble too with intricate detail missing in it’s presentation in the upper registers…….AND, would you believe, the other two bookshelf speakers I have held onto in my speaker collection because I like their sound are Mission 760i & 760i SE.
My taste in speakers must be the same as the writer of this review.
We either do have similar tastes or the Missions are simply good speakers while the Diamonds and Tannoy M’s are not 🙂
The Missions certainly prove that you can get good, full (if you don’t mind the lack of low bass) and open sound out of a small(ish) speaker.
This is a nice theological treatise posted above.
We often don’t hear things the way they are – we hear them the way WE are…
The Diamond 8.1’s are simply awesome audiophile quality speakers that please the discerning ear.
Highly recommended when you actually own a pair that “work”.
The ambiance and midrange are simply beautiful and they produce enough bass that a subwoofer is an insult.
Go Diamonds !!!
We disagree and there’s nothing theological about it. We tried these speakers in a number of rooms and combinations, nothing we did made them sound sound even remotely good. We tested two pairs, one of them in a perfectly good working order, the other after successful repair. Ambiance and midrange are OK, I certainly wouldn’t say “beautiful”, but they are acceptable. The amount of bass is barely enough for a ported speaker of that size, and its quality is acceptable only if you don’t try to boost it (again: acceptable, not good, certainly not audiophile). Highs are a disaster.
In our opinion, they are perfectly fine speakers if you only listen to things like acoustic Bob Dylan albums. Put on anything that has treble and bass in the mix and they’re sorely lacking.
The one thing I agree with you on is that this review, like all reviews, is subjective. So if you own and like the Diamonds – good for you, and you should definitely go with what your ears tell you.
A very informative post – thank you !
I had exactly the problem you describe in connecting an AV amp and a HiFi amp but room for just one set of main speakers.
After much reading I decided on an Amp switch box – this being the simplest and most effective solution.
My concerns were one of multiple connections in the music chain and a believer of as few as possible …
However needs must and reading your excellent article realised that the simple switch/wiring ie. no additional electronic wizardry was needed thus very minimal interference with the music signal.
I then succumbed to my lack of skill in building etc – my soldering skills are non existent and not too competent so the credit card was broken out … I bought a DYNAVOX AMP-S.
Looking at the inside I was pleased to see it very much resembled your creation above – simple switches, connectors & wiring.
Whichever method is chosen – I totally agree with you – you cannot tell the difference from a switched connection to a direct connection – to my ears anyway !
So thanks again for your very informative article 🙂
Glad I could help! I looked at the photos of the inside and Dynavox AMP-S looks good, it has a different type of switch inside, but according to product description it does switch ground as well. Remember, don’t use this switchbox with a tube amp unless you’re sure it can be on without load. If you have a solid state amp – no problem.
are you still doing restoration work on Marantz receivers
We sure do. Bear in mind we mainly do cosmetic work, cleaning, adjustments and necessary repairs. We don’t do things like full recaps, led upgrades etc.
I am not sure I sent a note I too have a 2250b needing restored. Do you still perform this
Hello Rafal. Thanks a lot for such an extraordinary tutorial. Just one question. If I wanted to use the selector with a Class A Tube amp and a solid state home theatre amp, would you recommend adding a resistance to any of the plugs? Thanks for any help!
I wrote it in response to an earlier question, so let me quote myself: If you want to use this switchbox with a tube amp, it is quite likely that your amp should not work unloaded (with no speakers connected to it. A possible workaround is to use a dummy load – a resistor connected in parallel to the amp’s speaker outputs. The resistance value of the resistor depends on your amp’s recommended speaker impedance. As far as power rating goes – higher is better, best to match or exceed your amp’s rated power per channel, definitely do not use anything below 10W.
If you do that, first check whether (and how) this dummy load affects the sound. It might have little or no effect (for example volume drop that can be easily corrected, you have to match volume of both amps anyway), but it might also alter the sound enough to make the amp sound worse.
se io mi ricordo di commutare su valvolare prima di accenderlo,non avrei problemi.Giusto?
Teoricamente sì, ma la parola chiave è “se”.
I have it’s little brother. The su7300k. Together with it’s tuner. Had before, a su z1/st Z1. Both of them, reasonably good amplifiers. The later, has a STK output (stk 2028, just the final stage) and the 7300 is much about the same with 7700 regarding construction. But: I ve heard the 7700. It is a nice amplifier, nice sound, well built, but different from 7300. While 7300 is more mod centric, but also hits both highs and lows. I use some jbl lx 66 speakers and some old rft speakers (east german, very good) and both are well driven by 7300 (not simultaneously). 7700 has a better driving. However, i do not understand, why 7700 and 7300 are different, regarding the sound. While they are much about the same. Also, a better sound can be obtained from the lower…stk0049 based…7100. This STK series (0029-59) were quite good. The Z1 sounded really nice, powerfull, and quite punchy and grunty for it’s size and demands.
Technics speakers, if speaking about the old high end speakers, they are damn good. If speaking about after 1990 speakers… Forget it.
I also had a pioneer 706, and did not like it. To much bass, to mudy, and shrilling highs and grounting mids, with no deffinition of sound. Of course, now we are talking about low cost amps ( Technics SU-7700/7300, pioneer 606 /706). Higher end are always good, no matter it is a technics, pioneer, Sony, etc. but in that class, there are other demands. Technics SU-V8, Pioneer Sa 9800, are (among) their top offers.
I may have missed it in all the comments above, but to control 4 speakers it appears I have to make 2 switches boxes as you described above – one toggle switch for A Speakers and one for B Speakers. Is there a way to have 1 toggle switch control 2 amps to 4 speakers? Thanks!
Short answer is: no. But you can build a single switchbox with two toggle switches. The first switch selects the amp (A or B), from which you take the audio signal, and passes that signal to the second switch, which selects the speakers (A or B). You’d need one additional set of speaker wire connectors, more speaker wire for internal wiring and one additional toggle switch. As far as wiring goes, you connect outer rows of contacts of each toggle switch to speaker wire connectors and the inner rows of contacts of each toggle switch to each other. Mind the channels and polarization. Hope that’s clear enough.
Similarly to others, I have a 5(7).1 amp for my home cinema and a vintage 2.0 amp dedicated to phono and CD. It makes great sense to share my front L/R speakers between the two setups.
I have just rammed the speaker wire from each amp into the speakers and am getting a perfectly acceptable result. I had no idea the risk I am taking.
Given that there are 1 > 2/4/8+ speaker switches for peanuts, I simply cannot believe that there is no commercial solution available at an appropriate price for the reverse.
Going to attempt to build one of these asap. Thanks for your expertise!
Good luck! And better pull out one amp’s wires from the speakers before it’s too late. A friend did exactly what you did and everyfing was fine – until his kid came over, tried to listened to music and turned both amps on. He got lucky, only one amp was fried and it was repairable.
There are commercial solutions available, but the ones confirmed safe are usually quite expensive. If you have the skills, it’s much cheaper to build one.
I have a service manual for the Superscope R-1250. It says to measure for dc offset and adjust R761 and R762 for 0 volts. Then it says put a scope of the speaker outputs. At 0.5 Watt adjust R763 and R764 for no crossover distortion. It then says Caution avoid excessive bias current. (20mA ~ 30 mA at no signal)
The amp section in Superscope R-1250 is different, it’s a 25W per channel amp, so the procedure is similar, but not the same. Another problem is, not many people have a scope at home. In most cases, people have to adjust without a scope, which means adjusting to mA or mV values.
How important is it to use the same gauge wire in the switch box as from the amps to the switch box and from the box to the speakers?
Less important than using the same gauge wire for internal wiring in your amp and speakers. In other words, nor very important. The wire sections inside the switch box are very short, so as long as you use decent quality wire, you’re good, there will be no significant current loss or wire resistance. I probably wouldn’t go below 14 AWG, but that’s about it. Unless you REALLY care about wires. Then, by all means, use the same type of wire for connections and the switch box internal wiring, but also change all internal wires in your amp (from the power amp section to speaker connectors, assuming there are such wires in your amp) and especially in your speakers as well, because those wire sections are longer.
Thank you for this simple solution to my problem. I have but one question for you. Do you wire all of the positive leads on on one side of the switch, and all of the negatives on the other? I understand wiring the pairs for the speakers on opposite sides to witch them, but don’t understand how the polarity in each switch position is maintained.
No! Don’t connect it like that, if you do, you will fry both your amps (if by “side” you mean longer side).
I’ll try to explain.
If you look at the connector part of the switch (the back, where you connect leads), you can compare it to a rectangle with sides 3 x 4, where the numbers 3 and 4 correspond to the number of connector on each side. Now put it down on the longer side (long side horizontal, short side vertical). You will get 3 rows, each row has 4 connectors. You also have 4 leads for each amp and for speakers. You connect amp 1 leads (positive and negative) to the top row. You connect amp 2 leads (positive and negative) to the bottom row. You connect speaker leads (positive and negative) to the middle row. The order of leads in a row doesn’t matter AS LONG AS IT’S THE SAME IN EACH ROW. If it’s the same in each row, polarity is maintained.
So, if you connected amp 1 left positive lead to the first connector in the top row, you then connect speaker left positive lead to the first connector in the middle row and amp 2 left positive lead to the first connector in the bottom row.
Then you connect amp 1 left negative lead to the second connector in the top row, speaker left negative lead to the second connector in the middle row and amp 2 left negative lead to the second connector in the bottom row.
Then you connect amp 1 right negative lead to the second connector in the top row, speaker right negative lead to the second connector in the middle row and amp 2 right negative lead to the second connector in the bottom row.
Finally you connect amp 1 right positive lead to the second connector in the top row, speaker positive negative lead to the second connector in the middle row and amp 2 right positive lead to the second connector in the bottom row.
Or, there’s a table in the article above that shows how to connect leads to the switch. You can refer to that table.
I hope I explained it clearly. If you still have doubts, let me know, I will try to draw you a diagram and email it to you.
Hello Lisinski. I need help from you to resolve my problem about tweeters on my Wotan MK5. I bought this speakers about month ago and last week, after many days of suspecting, i open box of tweeter ribbon and realise that someone put a cheap chinese ribbon in there. So there no option for me to send my ribbon to Quadral to reapair because no original parts in it. Tell me if you know, can i put for example this tveeters “VIFA XT25BG60-04- 4ohm/100W” to replace original (XX1000 T55/10/XX1000 Art.-Nr.:923023)?
I try many times to find parameters for original XX1000 T55/10 but without success. I need information about Ohms, watts, frequencis and sensitivity to be able to put some other tweeters to change originals and avoid damage on crossover.
Thank you in advance!
Zoran from Serbia.
Unfortunately I do not have specs for the original XX1000 tweeters. As far as I recall, they are 8 ohm tweeters. I can test that for you and confirm later – as I have 4 pairs of Quadrals with these tweeters at home, so I can take one out and measure. But I do not know their power handling or sensitivity. As far as frequency range goes, the crossover frequency for the tweeter in Vulkan Mk V is set at 4 kHz, which means any tweeter that works from that or lower frequency up will be OK (crossover freq. 4 kHz just means that the tweeter will not receive signals below 4 kHz). That includes the VIFA XT25BG60, which is good from 1 kHz up. It’s a 4 ohm tweeter, but the Quadral tweeters I used as temporary replacements were 5 ohm and that worked well, it did not cause any problems. Using a different impedance tweeter should not be a problem for the crossover, but such a tweeter it might play louder than the original 8 ohm tweeter in the same system. This is possibly in the case of the Vifa tweeter. And it’s actually not bad, because if the tweeter is too quiet, you would have rebuild the crossover, but if it’s too loud, you can fix that by adding resistors (L-pad – 1 resistor in series, 1 resistor in parallel with the tweeter) before the tweeter. They will attenuate the tweeter to the desired level. The value of resistors depends on tweeter impedance and how much you want to attenuate it. There are online L-pad calculators that will tell you which resistor values give you which attenuation.
If the Vifa tweeter is the right size, I would give it a try. Best get it from a store that accepts returns and if it’s too quiet in this speaker, just send it back. If it’s too loud, try L-pads.
I would do my best to avoid doing any permanent changes to the enclosure (tweeter mounting hole). This way, if you are lucky and find original XX1000 in the future, you will be able to restore your Quadrals to their original condition.
Thank you very much indeed for this solution: I was looking for it for a long time.
Since a relay and a toggle switch work the same way, IMHO switching could be done using this method. This way amplifiers would be turn off before switching improving their protection (as if belt and suspenders were worn).
I think I am clear on how the speaker wiring should be done both using one 4PTD or two 2PTD relays. But, How should connections be done to power each amplifier?
To be more precise, my question is whether it is possible use the same line that activates the relays to power one of the amplifiers.
Here is an schematics with two 2PTD relays of what i mean (NO normally open, NC normally closed, C closed; A1 amp1, A2 amp 2, SP speaker):
PwrSupply (in my case, both A1 & A2 need 12V and 7.5A máx.)
Initial Switch (a simple A-B positions) —-12V——> To A1directly
| Relay 1 (Left Channel)
| NO A2 L+ NO A2 L-
| C SP L+ C SP L-
| NC A1 L+ NC A1 L+
| Relay 2 (Right Channel)
| NO A2 R+ NO A2 R-
| C SP R+ C SP R-
| NC A1 R+ NC A1 R+
To power A2
Thank you in advance!
My whole point was to make the switchbox completely passive, as safe as possible while keeping it as simple as possible AND for it to work safely while both amps are on. If you use a break-before-make 4PDT toggle switch, there is no need for additional protection, like powering down amps before switching, extra relays etc., because the mechanical switch ALWAYS completely disconnects one amp before connecting the other amp. Unfortunately I do not have enough experience with relay-based systems to check your solution. I find mechanical switches more reliable and I try to reduce the number of devices that need to be powered, so I’ve never explored relay-based powered solutions. Quite frankly, if I wanted to switch 12V power to amps together with speaker connection, I would simply use a 6PDT switch (additional 2 lines would switch 12V to amps). But this solution would switch amps on/off at the same time as switching their connection to speakers.
Thank you very much for your kind and quick reply.
I will keep your proposal as it is for my project.
I’m quite a newbie to all of this electronic stuff and maybe I have thought too high for a begginer…
I was wondering if you might have a schematic diagram that I could download?
We don’t, but the device is so simple I don’t think you need a diagram. It’s basically this:
inputs from amp (sockets) –> wire –> toggle switch inputs -> toggle switch outputs–> wire –> outputs to speakers (sockets)
Connection to toggle switch – see table in the article.
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Hi Rafal – you said that you could get these T55/10/XX1000 from Germany – is that still the case? I have two that either need repair, or replacement. Can you guide me to where I might find some?
I think German ebay is your best bet now. You could also contact Quadral, they don’t sell replacements anymore but I hear they still do repairs. But they charge a lot and you’d have to pay for shipment to Germany and back.
Just in case, have you checked the tweeter fuses (near wire posts)? If they’re blown, the tweeters are near silent.
Oh wow, I can’t believe that I didn’t think to check the fuses. Indeed, both are blown. That will be my first step. Thanks!
Good, there’s a chance that the tweeters survived. You need 600 mA (0,6 A) fuses. Let me know if the tweeters work 🙂
I got the correct fuses, installed them and….. nope. No difference. I still don’t hear anything from the tweeters.
I’ve sent Quadral and email, and they’re going to put me in contact with someone in my country.
I can’t help thinking (or maybe it’s wishful thinking) that there’s something obvious that I’m missing.
Hi! I have 2 enbee speakers and an enbee EA 50 B stereo amplifier for sale. Speakers are large. Can anyone interested in purchasing the set please contact me? They’re too lovely to be dumped and were working fine 2 years ago.
Thanks for the article and the comparison: it says exactly what we think a group in Telegram in Spanish (Superaudion) where we love these headphones for the sound adjustment they have at a decent price
You gorra should edit the fourth paragraph (reapeating phrases).
Hi, I just bought a SpecialTy/AV switch and plugged everything, 1 pair of speakers and 2 amps.
What happend is that I lost the sound of my subwoofer, which was connected to my AV receiver through the LFE cable.
Can you please explain what happend and how I should connect my subwoofer, so I can get the sound back.
In theory, the switch should not affect your subwoofer at all if it’s connected to your AV receiver’s separate output with a separate LFE cable. I would have to know the details of your system (models of the receiver, amp, speakers, subwoofer and exact connections) to try to figure anything out. Just in case, check your receiver’s speaker settings, maybe they changed for some reason.
I have the R-1280 model. It seems quite rare. I can not information on it anywhere.. It keeps blowing 2 of the fuses. I cant even find a schematic for it anywhere.
Very good rightup on the 1270
Unfortunately I don’t have a schematic for the R-1280. But on the outside it is nearly identical (different finish, but exactly the same functions, layout of buttons and sockets etc.) to the R-1270. Look at the photos of the R-1270 and compare to what you see under the hood of your R-1280. Compare the boards, output transistors etc. Maybe it’s the same receiver with updated looks, or at least similar enough to use the R-1270 schematic to repair your R-1280.
If it is identical or very similar inside, do let me know and send me a few pics, I will add this info to my article.
Hy my dad has enbee zx80 system.my dad does nt have the manual for the system and we want to connect with a smart tv. Can you please help us by providing the manual and the way to connect with the smart tv.
Thanks you it will be a great help.
I do not have a user manual for the EnBee, but I don’t think it would help you anyway. The way of connecting it to a smart TV depends on the connectors the TV has. Most of the current smart TVs do not have analogue audio outputs, only digital. EnBee, on the other hand, is fully analogue and has no digital inputs. That means you will probably need an additional device called DAC (digital to analogue converter) between the TV and the EnBee. This device will convert digital audio signal from the TV to analogue audio signal that the EnBee can receive and reproduce. To give you more details, I would have to know the exact model of your dad’s smart TV. Also, please confirm that your dad also has EnBee ZX1 (the preamplifier), not just EnBee ZX80 (the power amplifier).
I want to buy it if you are not interested in using it ofcourse. Please contact me at email@example.com.
Bought the headphones and love the sound.
I would add that these are not workout headphones.
They are a little loose on my head. Though I do have a small head.
Glad you like them, so do we! True, these are not workout headphones, but over-ear headphones are generally not good for this purpose (even ones with a tighter fit), ear get hot and sweaty fast! In-ear or very light on-ear phones are much better for workout and running.
I just found your helpful Switch box and read all the comments 😉
I have a Cayin a55 T Tube amp and a Cambridge Audio amp. I understand that there must be a load to the tube amp before turning it on.
I want to make a swith for 2 amps and two pairs of speakers. When I have 2 pairs of speakers connected to a second 4DPDT switch, isn’t there always one pair of speakers connected to the tube amp ? So I don’t have to put a resistor extra ? Please help if I’m wrong 😉
Can you please provide a short drawing, how to connect the resistor in the switch box ?
Many thanks for your support !
Regards from Bavaria
No, if you use 2 switches, one for amps and one for speakers, the amp switch is first in the chain (amps->amp switch->speaker switch->speakers), so when you select one amp, the other will be disconnected from speakers.
The resistors in the switchbox should be connected to (+) and (-) of each L and R tube amp input – one resistor across tube amp R+ and R- input, the other across tube amp L+ and L-. You can also connect them across the tube amp’s speaker outputs.
Many thanks for your help !
I am having a hard time looking for one woofer. To replace.
It’s been over a year looking. I can not believe you found 2 for 40$…
Well I will keep looking one day may get lucky..
Yes, I was lucky to find them so cheap and fast. Maybe try looking for Quadral Dauphin speakers in a bad shape but with working woofers. They’ll be a bit more expensive, but should be easier to find. The woofers I used in this project were originally from Dauphins. They were a perfect match physically (shape, size) and at least a good match sonically.
Hi Rafal, Thanks for the very informative post. The best I have seen from many, with regard to this particular switch. I have been crawling the net to get info on ‘Two amp, one speaker’ switch but didn’t find any as detailed as this thread!
I intend buying either the ‘Specialty-AV SP-71’ (https://www.amazon.com/gp/product/B0796KGVXT/ref=ox_sc_act_title_2?smid=ADXERLXGK7AZN&psc=1) or the ‘SOLUPEAK P2 2(1)-IN-1(2)-OUT’ (SOLUPEAK P2 2(1)-IN-1(2)-OUT Amp Amplifier Speaker Switcher Selector Switch Splitter 2-way loudspeaker control combiner box). The cables that I use are QED xt40i which are 12 gauge. The connecting wires on both these switches are 14 gauge. Hence I was wondering if there would be a drop in SQ, with either of these switches connected? Also would appreciate your advise on which would be the better choice. Will go with whatever you say. BTW the amps are Cambridge Audio Azur 851A (Integrated), CA 200M DAC, and Denon AVR. Speakers – Definitive.
The Specialty-AV SP-71 switch looks good. It has been discussed here before, by the way. It does not have common ground (good) and it is ‘break before make’ (good). Switching left and right channels separately is a minor inconvenience. I can recommend this switch.
As far as the SOLUPEAK P2 switch, it’s unclear whether it has common ground or not. Without knowing this, I can’t recommend it.
Don’t worry about the internal wires being thinner than your speaker cables. These are very short sections, they shouldn’t affect SQ. The switches in the switchbox might, adding a switch in the signal path can degrade the sound a bit. But with switches of this type, any change in sound should be minor or inaudible.
Thanks Very much Rafal. I too was inclined towards the SP-71 as it has been around for awhile. Was just waiting for your response to go ahead and buy it. Thanks again and all the best.
I bought this one from Amazon https://www.amazon.com/SOLUPEAK-P2-Amplifier-Switcher-Loudspeaker/dp/B093GSS8P7/
it using a 4PDT switch and does not have common ground，same as your design and everything works fine.
Thanks for the very informative post.
That’s great. Actually a comment was added on Amazon in October 2021 with a photo that shows a 4PDT switch (KN11-402) so yes, it is indeed the same design.
Swap out a couple of crossover capacitors and you ll have a fantastic sounding, beautiful set of vintage Japanese lattice-grille speakers. I used to own a set of these myself, they re great performers when paired with a suitable amplifier, and they really look fantastic in any room. Sony doesn t get a lot of love today (although their yellow Kevlar-coned speakers are actually quite good sounding and have very extended treble frequency response great for EDM, at the expense of being very inefficient) but their vintage offerings were quite well respected. These big, powerful 3-way speakers offer the very unusual set of square-framed woofers and midranges, too. Definitely something different!
I think you’re talking about completely different speakers, JBL L96 don’t have lattice grilles, square-framed drivers, and they were not made by Sony or in Japan 🙂
I do agree that some of those vintage Sony speakers are very interesting though.
Great review, loved the comparison with Chi-fi. Was wondering should I try these or not and now I will definitely try these, as they seem to have a generous return policy.
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I own a Denon PMA-360 black from this era. I absolutely love this amp, I don’t know why they aren’t praised for their quality of sound. It drives almost all the speakers I have perfectly. I like to mention that these denons are very good with antique full-range speakers, I have a 12 inch Philips AD1255/M7 and it does a brilliant job with them.
The sound of these Denons varies model to model. We tested a PMA-350 II and that one was actually nothing special, an OK amp for its price, but didn’t come close to the magic of PMA-250. Good to know about PMA-360 though, we’ll sure try it if we have a chance. But your comment about good synergy with antique full-range speakers suggests recessed mids and boosted bass, which would be closer to PMA-350 II sound, not PMA-250 (mids a bit forward).
In fact, I have an M1 and it has the same board as your VMK20. Weird.
Are you sure you’re not looking at my photos of M1 boards? If not, it’s possible that M1 was upgraded and I’d be very interested in a few photos of the boards in your M1 (my email is in the ‘about us’ section). In any case, part of the difference is in chip programming, so the sound difference might still be there (unless the programming has been copied as well). Better ANC boards would certainly mean an improvement of that system.
> Are you sure you’re not looking at my photos of M1 boards?
I am – at the very least, mine is based on QCC chip rather than the old CSR. And has these improvised dampers.
Will send you pics somewhat later! 😀
Any news about that?
Actually, yes. I got a few photos of that newer version of M1 (brand Teeline) from the owner and compared them with my Valcos. When it comes to components, that version of M1 is definitely closer to the Valcos than my M1. It is not identical though, there are differences on both ANC and BT/DSP boards. I’d say that the Valco is an evolution of that Teeline M1. I would also guess that Teeline version of M1 should have better ANC than my M1, closer to or as good as the one in Valco.
I could not compare the sound myself, because I only saw the photos. The Qualcomm chip is the same, but it’s application is a bit different (there are differences in some smaller components), plus a lot depends on DSP programming.
According to the info I got from the owner of Teeline M1, “wired and BT mode sound similar” – that’s very different from Valcos, where wired and BT sound lice completely different headphones, “but not exactly the same (I cannot do an actual A-B test – when you connect the jack, Windows doesn’t automatically switch sound device for whatever reason). Also, in BT mode volume is half the volume of wired mode (assuming default Windows logarithmic volume scale). However, when you enable ANC, sound has significantly more bass.” That is different from Valcos as well, they do not have more bass with ANC on (thankfully).
In short, Valcos appear to sound much different from Teeline M1 as well.
My Marantz 4240 receiver (US model) has been an amazing experience through the years. Long after my speakers needed restoration, my receiver just keeps delivering amazing tones and power. Purchased new in 1978/79, the system has been without issues. However, just in the last month the two right speakers are not working. I’ve read online that it is likely a fuse and that fuses for the 4240 are hard to find. Any thoughts on problem and solution?
I don’t see how fuses for 4240 could be hard to find, they are standard fuses. I understand that by “two right speakers” you mean right front and right rear channels? This could be an issue with power to right main amp board (including fuses), but could also be as simple as dirty contacts somewhere. Clean all the switches (especially the REMOTE/LOCAL switch on the rear panel), bridge PRE OUT/MAIN IN jacks with RCA cables (there are contacts inside that sometimes cause problems, RCA wires bypass them), check fuses (you’ll find them under the bottom plate). If that doesn’t work, find a good technician to diagnose and repair you Marantz.
Great reviews! I just acquired a restored 1060. I have been using a McIntosh MC2002 amp with a McIntosh C11 preamp driving Allison One speakers. Decided to give the 1060a shot today. I have a medium sized(at best) room. The One’s supposedly like a lot of power, but when sold they were spec’d at needing only 30 watts for 100db. Anyway, plugged it in, put on a ’73 Dead show leading off with Dark Star and…Oh my. Huge gobs of bass, incredible separation, just a big powerful sound. This amp was made for these speakers. I had actually used the amp portion along when I first got it with the C11, because the C11 cost me thousands of dollars and it is a great preamp. And the 1060 amp sounded very good. But together with it’s preamp, it’s a different animal all together. I am truly smitten.
I have McIntosh MC2300 that is currently on the sidelines and undergoing repair. I hope it will be eventually repaired, at which time I would love to use it in a biamp situation with it pushing the woofers and the 1060 the highs. But I could live the with 1060 alone forever. It’s that good.
The 1060 is certainly a (relatively) little amp that could… And still can! It has the right balance of clarity and smoothness. Very hard to beat in a small or medium sized room. Interesting to hear that it’s preamp section can compete with a tube McIntosh.
Somewhere around 1990 I used my good ol’ 1060 and a pair of KLH1s to FILL our High School’s Auditorium (150-200 seats) with sound for my daughter’s Dance recital. It was great!
Hi, I have this exact amplifier.
The edd engages by pressing it’s button however the sound doesn’t stop when this is engaged… With nothing connected to the edd inputs. Neither XLR nor unbalanced.
Also the adaptor button for a graphic doesn’t cut the sound when it is pressed and nothing attached to the in/out jacks.
I’m thinking that the tiny relays that these functions rely on need a clean.
The one I mean is at the top right of your picture.
Tell me, does the clear cap come off?? Can I just spray deoxit into that and see if the adaptor circuit starts engaging..
I’m simply looking to find out how to clean those three relays..
1 for graphic equaliser (adaptor) button
One for edd on and one for switching between XLR and unbalanced inputs..
Those seem to be the circuits not responding to switches despite the led showing edd engaged and then unbalanced switching to XLR.. yet nothing on the output…
With small relays, it’s usually safer to replace them, opening relays is always risky and small ones are even easier to damage when trying to open them. Cleaning relays by simply spraying deoxit inside is a very bad idea. That can also damage the relay. One way to do it right is to clean the relay contacts only with a strip of paper dipped (but not dripping) in a cleaning agent, and the dry the contacts with a dry strip before closing the relay.
Also, based on your description it actually sounds more like these functions have been bypassed in your amp. Dirty relays would probably still affect sound when the function is engaged, they would just be intermittent. No effect whatsoever sounds like a bypass. I’d check that before doing anything. Look at the underside of the main PCB, under the relays in question, there may be a solder or wire bypass there.
thanks…. yes that’s sound advice, excuse the pun.
I’ve noticed that it has started working now,
I’m thinking its a bad joint on the resistors mentioned, or it is the relay that needs careful cleaning or replacement..
I really enjoy this amp and I’ll have to give it some attention.
I will keep looking out for its symptoms now It is working. It appears to engage the EDD a minute or two after I switch on the amp as I leave it switched to edd.
I have a Superscope R-1240 in really good condition. Doesn’t look like anyone has ever been inside it.
It did come with several issues. Dead signal meter and of course burnt out lights.
Big issue is the volume pot. Left channel still is has volume when pot is at zero (Right channel has no sound at zero). I figure that the wiper is off a bit on the shaft and maybe able to be fixed. But, if not, can you tell me what volume pot you used on your R-1270? Did you find a Superscope one or did you use a Marantz one. The part number for the R-1240 is RM0254023 (according to the manual) and RM02540232 (according to the part number on the pot itself) – 250K X2. Not sure if the R-1270 and R-1240.
Hi Paul, I had exactly the same problem with the volume pot in my Superscope (channel imbalance at low volume, one channel had sound at zero volume). If I remember correctly, I used a generic volume pot obtained locally. As long as the pot physically fits, has the right taps and the right specs, it will be fine. Dead meter – I’d start with checking the electrolytic cap on the meter, it might be the culprit.
I plan to take it apart, inspect and try and fix. It’s the left channel and corresponds to the front wiper which actually controls the stops (zero to full volume). My bet is the wiper disc is cracked causing the wiper not to go down to zero. Looks fixable
If not, I think this is an option: https://www.amazon.com/gp/aw/d/B07PTRSJB3/ref=ox_sc_act_image_1?smid=A1564KB351MEZB&psc=1
Hi Rafal and Paul – found this as I am also working on a Superscope R-1240…it had a blown transistor, which I have replaced and it seems to be working very well. Planning on doing a full recap also. Luckily my volume and other pots seem ok so far…
Paul – I was wondering how it is going on yours? My meter (and the light for it) is also not working. I changed the capacitor and no change. Just wanted to check if you found the problem before I get into it?
Also wondering if either of you have any idea on the bias setting?
I haven’t found the R-1240 SM for free anywhere. Your best bet is to do what I did – find a Marantz receiver from which this Superscope’s amp is copied and use the bias adjustment procedure from the Marantz SM, accounting for possible different resistor values (like the 1270 had). I would start with comparing the amp section in your Superscope R-1240 to Marantz 2220.
Unless you’re willing to buy the SM, then it’s apparently available here: https://www.vintageaudiostore.com/products/superscope-r-1240-receiver-service-manual-original
But: I’ve actually found the SM for R-1270 some time after writing this article and the procedure for bias adjustment is useless for me (it requires an oscilloscope, which I do not have). It’s quite likely that it will be the same for R-1240.
I have the R-1240 “Service Data” manual and can confirm the DC bias/offset is adjusted by the inner pots (R761 & R762) on the P700 main amp block (the one connected to the heatsink). With selector switch in the “AUX” position, Adjust R761, R762 for “zero” DC output (at the speaker outputs)
Idling Current is adjusted using AF oscillator connected to the AUX jack | 1000 Hz | connect oscilloscope to speaker terminals | adjust R763, R764 (outter pots) for no evidence of crossover distortion at 500 mW output.
CAUTION: Avoid excessive bias current
(20 mA ~30 mA at no signal).
Thank you, that will be very helpful for all the R-1240 owners out there!
I’ll just add for anyone who does not have an oscillator and wants to adjust to a safe value: 20 mA at no signal should do the trick, for mV value adjusted across output resistors – calculate based on the value of resistors.
I have one of these, it all works apart from the extended drive, when I press it with an input connected, no sound at all??
For Extended Direct Drive to work, a source should be connected to one of the two Extended Direct Drive inputs (XLR – Balance, or RCA – Unbalance), and THE SAME Extended Direct Drive input (either Balance or Unbalance) has to be turned on. If that doesn’t work, your amp might need repairs.
Hi, fixed it, it was the 6 resistors inside the front panel needed resoldering, the extended direct drive works now!
That’s great! Bad solder joints are sometimes a bugger to find, glad you managed to locate them.
was it hard to get to the resistors. all I”ve done with mine is remove the shell to peer inside at the main board and identify the small relays with clear shell. I can of course remove the knobs but is there much work to access the resistors…mine works but it doesn’t switch to edd until a minute or two after I turn the amp on. I leave it in edd but it still takes a minute or so to switch across.
Looks like it needs to warm up to get a good contact or to get the right voltages. Not sure it this is a normal behaviour or something that should be corrected. But my friend owns this amp, I’ll ask him to check how his unit behaves when switched on with EDD engaged.
In my friend’s SU-VX800 EDD engages right after turning the amp on, so if yours has a 1-2 minute delay, it means that something doesn’t work as it should. Possibly a bad capacitor somewhere?
Richard I have gotten fed up with the EDD cutting in and out as it sees fit
So I’ve removed the top, removed the top bracing/shroud and can see a bank of 6 resistors joints not far from the edd button.labelled R714 R715 etc …
Removing the front panel seems to require removing the remote switch connectors that have blue plastic slider ribbon and icant see how to do that.
Did you go that far or just touch the 6 resistor joints pairs in situ?
I believe I can access them
Also I have an adjustable temp solering iron that adjusts by digital display on the handle…from 180deg to 450deg celcius.
What’s your recommendation.. seeing as you’ve done this already.any particular temp? I can try 250 as a start..
Yes, you have to remove the remote switch controllers. Download the service manual (unless you already have it), you’ll find instructions for removing these controllers (both ends of the blue ribbon) with images on pages 8 and 9.
the article would have been even more interesting if you had documented some phases of the repair in particular that of replacing the coil. I myself had to replace the spiders of the woofers (122A) in my JBL l65 so I was curious about how did you manage that repair as I think some steps are in common with the replacement of the spiders done by me. Anyway thanks for keeping such great speakers like these still alive. 😉
How do I include a subwoofer in this switch? I have a passive powered sub (it has both Line In and High Level Inputs, but no outputs). I have a preprocessor that has a line out that I use to connect to the sub (then I connect the preprocessor to amp 1). The second amp I’m using this switch box with is an integrated amp and is only 2 channels so I use the high level outputs and run cables from this amp to both the speakers and the High Level inputs on the subwoofer. Should I go:
preprocessor -> sub
Amp 1 -> switch
Amp 2 -> sub
Amp 2 -> switch
Will that “connect” the two amps and cause problems? Should I instead go
Amp 1 -> switch
Amp 2 -> switch
Switch -> speakers and subwoofer
Scenario 2 sounds cleaner and safer to me. I would probably add one more set of speaker output connectors to the switch to accommodate the sub, but if you run wires from one set of connectors to both the speakers and the sub (connected in parallel) it will be OK too.
At last, a little love for this venerable receiver! I managed to find one with a few missing knobs that I had refurbed by someone capable. It sounds terrific and, as you rightly say, they look great too. Mine pulls in a very strong signal with just a basic indoor aerial and I use a step up transformer into the phono stage to run a Denon MC in a very standard Lenco 75. Lovely.
Ha Timo, ik heb er ook een waar 4 afwijkende knoppen op zitten. Hoe heb jij de juiste knoppen kunnen vinden? Zou de 160a graag weer compleet hebben als hart van m’n vintage set!
I think your best bet is to find and buy a faulty NAD 160s/160/140/120/60 (these models use the same knobs, other models from the same line have different knobs), get the knobs that you need and then resell the rest to get some money back. It will take some time to find it though. In the meantime, you can buy a set of 6 new aluminum knobs – they will be different from the original, but at least they will match each other.
I want to do this for the reason stated above of using one amp for turntable music and the other a Denon AVR that runs my theater set up. Same pair of Sonus Faber main speakers. Theses speakers have two sets of binding posts for bi amping. I’ve read elsewhere if I remove the jumper wires between the bunging posts the separated signals could not touch. Adding your switch as well I think as a fail safe. . Lastly the amp will be a tube amp so I will not turn it on ever except when the speaker switch is to the tube but I think theoretically being the amp would be connected to the speaker at all times without a switch, as long as it’s power was off, it don’t think it would get damaged from not being under load as if disconnect. I’ve also considered the switch may not be necessary at all with this set up as some folks do this for the purpose of actually running both amps simultaneously into the speakers for some unknown to me benefit. The entire key is the dual binding posts on the speakers with jumper wires removed. Oh, a few other last notes. The Denon AVR is actually only used as the pre amp for the theater, getting its power from a Monolith 11.2 amplifier. So not sure if some how there was a power clash if the Denon, the tube amp or the Monolith or all of them would bear them blow up. Shudder that thought. Any thoughts on this set up as a possibility would be appreciated. Sorry if this has been addressed previously in the many comments above.
That is NOT what two sets of binding posts are for and definitely NOT how bi amping works. With bi amping-ready speakers, if you remove those jumpers then yes, you can safely connect 2 different amps to the same set of speakers. But neither of the amps would power all drivers in your speakers.
Typically, the amp connected to the lower binding posts will power the woofer(s) (bass driver) ONLY. The amp connected to the upper binding posts will power the midrange drivers and tweeters (“treble” drivers) ONLY. The goal is to benefit from more power and control with 2 amps separately powering the individual drivers AT THE SAME TIME. But if you play music only through the amp connected to the lower posts, you will only hear bass, no mids or highs. If you play music only through the amp connected to the upper posts, you will only hear mids and highs, but no bass.
So no, the switch is not “just a fail safe”, you will need it if you want safely connect 2 amps to your speakers and use them separately. And the the jumper wires between the binding posts should definitely stay in!
For tube amp, add resistors to the switch to keep it safe in case it is turned on with speakers disconnected. See comments above for details.
If you build the switch according to my guide (with resistors added for tube amp safety) and use it as described, none of your amps is at risk.
If you connect both amps to your speakers with jumpers in through the switch, you will hear all frequencies from both amps.
If you connect both amps to your speakers like you wanted to, to upper and lower posts with jumpers out, you will either hear only bass or only highs and mids, depending on which amp you use.
If you connect both amps to your speakers like you wanted to, to upper and lower posts, but with jumpers in, you will hear all frequencies from both amps, but if you accidentally turn on both amps at the same time, you will fry the Monolith 11.2 or the tube amp, or both (but not the Denon, which is not connected directly to your speakers).
Thank you so much for this valuable information. I think I may be going about what I want to do in what is quite possibly the wrong way. I’d like to explain and get your thoughts. When it comes to home theater, I consider myself an enthusiast well above novice but no where near expert. I have what i consider to be a very nice home theater. (I actually have 3) in my home, but my main theater is a 14 x 20 room 7.4.2 arrangement. Being Two main speakers which are Sones Faber Venere S (In gorgeous walnut). This whole system as I think I mentioned uses A Denon 6700h as a preamp and a Monolith 11.2 for power That is 200 amps per channel to the mains and 100 amps to the other 9 speakers.
What I want to do is add for the purpose of listening to original press vintage vinyl. Classic Rock. (I already have a nice turn table that I can run through the main theater and also in my zone to which is an adjacent bar and lounge area and it rocks and sounds amazing.
What I want to add though is a another turntable. Modest set up It is a Fluence RT 85 that will run directly into a Monoprice all tube amplifier that puts out only 10 w per channel, but I’ve been told coming from an all tube set up is still quest a bit of power. I’d like to run this in the main theater as it the best room I have acoustically and will be great for the old warm tube sound and vintage records. So you think it might be best to set this up as a stand alone system in the same room with it’s own set of dedicated, quality speakers more on scale with the amp that will be running them? I would be open to that. I was thinking as set of Sonus Faber Liutos but would be open to ideas. I have room in my theater I think to do this second stand alone system tastefully. So your thoughts and any other input anyone suggests would be much appreciated. Thanks for reading.
Sonus Faber Venere S are 90 dB speakers, so they have average sensitivity (they are not not very efficient, but not very inefficient either). A 10 W per channel amp might be enough for them in you setup or it might be too weak. That depends on your listening preferences. You should try this tube amp with your Sones Faber speakers (disconnect the speakers from the Monolith amp first of course) and that will tell you if it sounds good and can go loud enough for you or not. If it does, use the switch (connected like I described above). If not, get more efficient speakers for the tube amp. Certainly not the Liutos, their sensitivity is even lower (89 dB) than SF Venere, which means that they’ll need MORE power from the amp to achieve the same loudness. Look for speakers with higher sensitivity – the higher it is, the less power from the amp the speaker needs to play loud.
Note that Monoprice Pure Tube is a version of a cheap Chinese amp that’s been on the market for a while under various brands. Do not expect quality manufacturing (expect cheap switches, potentiometers, finish that doesn’t look very well made up close), or a good onboard phono stage. But it’s very cheap, the tube sound should be there, and if you like it, you can always replace it with something better over time.
What adjustments are needed to make this for a 3 amps and 1 pair of speakers configuration? This question was kind of asked above, but not exactly the same. I prefer not to daisy chain, but to have one single unit. Thanks!
Daisy chaining 2 switches in the switchbox is the only way I can think of. To avoid that, you’d have to find a switch that has 3 sets of inputs, not 2. I have not found a switch like that yet.
You can build it into one unit, just put both switches in one box.
Great article, i too have a R1270, silver face. Nice sound, a little warmer than the Marantz 1070 sitting next to it. Have re-lamped with LEDs and it looks pretty. Pops on power off were fixed with a service / recap in the amp stage. Have noticed that at minimum volume there is still sound from source, do all of these behave that way or is there adjustment that is out?
James, yes it is a common behaviour in this model and it’s not a matter of adjustment. It’s a faulty (or poor quality) volume potentiometer. My R-1270 had this problem, as did at least two more units that I know of. With a new volume pot, the symptom disappeared.
It’s not a big problem and I haven’t heard of it getting worse over time. I replaced the pot in my R-1270 mainly because in addition to this symptom it also had channel imbalance that required compensating with balance pot during quiet listening.
I got 2 speakers now with a newer Stereo reciver I connect to my TV and Turntable.
But I got an old Yamaha receiver that I want to play with the turntable and still use the same speakers. So will this switch work for me?
I’m very new to this and haven’t build something like this before but I want to try. I found all parts but I don’t understand where should I connect the banana plug-ins..
Like the 4 ones on the outside of the box (highest up) should I connect my speakers there? And the other 8 (under the 4) banana plug ins, I should connect from reciver?
I hope you understand my English is not good haha.
This switchbox is exactly what you need.
Yes, in my switchbox the top 4 banana connectors are for connecting speakers, the other 8 are for connecting amps or receivers. In my case, upper row is for AMP1, lower row is for AMP2, but how you arrange these sockets on the back panel is up to you – as long as you know where to connect speakers and receivers.
The most important thing is: the 4PDT toggle switch itself has 3 rows of connectors, 4 connectors in each row. Connect banana speaker sockets to the middle row, AMP1 sockets to top row, AMP2 sockets to bottom row. And remember to connect L+, L-, R+, R- the same way in each row (in the same “column”).
And of course carefully check that there are no shorts (touching wires) anywhere – on the toggle switch itself or on the banana connectors.
Hi Aagain, thanks for a quick answer! 🙂
Alright now I understand, I will do same as you and follow instructions!
But I have one question I’ve tried to search but can’t find. I need to solder, I found these:
My question is, do I stick the fire thru that hole in the plate and then solder?
And what should I solder with?
Thanks again, I’m very excited about this project 🙂
Watch this video. It’s a different kind of connector, but the principle is the same.
You should solder with a soldering iron and solder wire, like the guy in the above video.
But: you can also try to secure the wire between the two nuts – you use the first nut to secure the socket to the housing panel, then you use the second nut to secure the wire. If you can do that firmly, you won’t need to solder anything.
Or: you even can attach the wires running from the amps and from the speakers directly to the 4PDT switch. In this case, you don’t need the banana terminals at all.
This last solution is less convenient if you plan to connect and disconnect this switchbox to and from different amps and speakers a lot (like I do), but perfectly fine if you just need to put it in your system and leave it there. And it saves a lot of time and some money 🙂
Thanks alot for the information Rafal!
I’m gonna try to solder it, I think it will be super after all the help I got from you.
I will post it for you when it’s finished 🙂
Have a great weekend!!
Have fun! Just remember to check everything very thoroughly before you connect the switch to your receivers. Any mistake in connections or a stray wire can seriously damage your receivers. And wear long pants and sleeves when soldering 🙂
Finally I had the time to complete the box..
Here’s some pictures:
Thanks again for all the help. Hope you have a great weekend!!
That looks great! Using a bigger box is a very good idea (convenience of assembly and use) if you have space for it.
hi there, found your page while searching for DIY speaker switch. Very informative and helpful.
I have some questions and hope you can help.
My hifi setup – 1x automatic turntable, 1x manual turntable, 1x CD player, 1x ITL 80watt amp, 1x NAD 25watt amp. And connected to B&W v200 speakers. I was thinking to link and switch 2 amps with 1 speaker set (as per your project). I was also thinking about of adding headphone+headphone amplifier to my setup. Would it be possible to have the amp switching capability with the headphone amp at the end of the line? what would you suggest?
Your help is really appreciated. Shanks
For speakers, the switch I describe will accommodate your systems.
For headphone amp, the best option is to take the signal from TAPE OUT of one of your amps, or from both through a line level switch – search for “RCA AV switch” to find one. Any cheap RCA switch will do. These switches usually have multiple stereo inputs and one stereo output, but you can use it in reverse and connect your amps’ TAPE OUT to the switch outputs and the switch input to the headphone amplifier input.
Tapping to speaker outputs to get signal for headphones is also an option, but that makes sense only if you use resistors to reduce the signal to headphone level (that’s actually how headphone sockets in many amps work, probably including your amps) – not for feeding a dedicated headphone amp.
I just bought a 1978 Pioneer SX-780. It is beautiful but the headphone jack receptacle is noisy. Any reason why one of the three devices you discussed would not allow me to successfully use my headphones without having to have the headphone jack receptacle repaired? Thx for any thought you would be willing to share.
I would have to know more about the kind of noise you have and about your headphones to diagnose the problem with certainty, but the two most common noise issues of headphone jacks in vintage receivers are:
1. crackles, intermittent sound when connecting headphones and/or while listening; the noise may change or even disappear for a while when you move/twist the headphone plug in the socket
2. background noise (it can be hum or white noise) present all the time, with intensity that may but does not have to increase as you increase volume.
The first issue is usually due to a problem with the headphone socket itself, in most cases dirty/corroded contacts inside the socket. Cleaning these contacts or replacing the socket will fix the problem. Also, in such case, yes, you can use a “can opener” instead of repairing the socket and you should not have a noise problem.
The second issue is a result of how the amp’s designed. Most amps and receivers, especially those from the 1970s, draw the signal for headphones from the amp’s speaker outputs. That signal is simply reduced from speaker level to headphone level by resistors. It is the same solution as the one used in “can openers”. The problem is that most amps have some background noise. In most cases, the amount of that noise is too small to be a nuisance when you use the amp with speakers, or with headphones that the amp was designed to work with. Headphones from the 1970s usually had high impedance and low efficiency, they needed stronger signal to generate sound. With such headphones, amp’s background noise is inaudible or very quiet. But many modern headphones are designed for much weaker signal from mobile devices and have completely different specs than headphones from the 1970s. This means that you will hear much more background noise if you use efficient modern headphones. If that is the problem with your Pioneer SX-780 and your headphones, a “can opener” will not help at all, because it works just like the headphone socket in your receiver and you will hear the same noise. The solution is to either use different headphones (less efficient, with higher impedance), or you can add a cable with a volume control potentiometer to your headphones to decrease the level of signal from your amp to the point where you can’t hear the noise anymore.
It will be a cold solder joint on the resistors behind the front panel
Could be, although with a cold solder joint it’s usually an intermittent or no sound, not delay.
Richard I have gotten fed up with the EDD cutting in and out as it sees fit
So I’ve removed the top, removed the top bracing/shroud and can see a bank of 6 resistors joints not far from the edd button.labelled R714 R715 etc …
I believe I can access them
One of my friends has this amp and needed radiators for those transistors without radiator. He modified it.
The amplifier was delivered with a special 1,8 m power cable, with a FIGURE 8 massive connector and a thick 2×1 mmp KAWASAKI CABLE and a 16A plug. In case of second hand, many cables were lost but ordinary cables are compatible. Be careful, the amplifier has high power consumption. If operated at low volume, the 2×0,75/ 2,5A plug does the job ok . Some ( non Europe models and some multivoltage models) where available with the computer type power connector.
True, some of these small transistor tend to overheat and definitely need a heat sink.
Using a fig. 8 AC socket is really unfortunate. Like you said, many people don’t have original power cables and use these amps with ordinary cords made for devices with much lower power consumption. It’s better to either build your own power cable, replace the fig. 8 socket with a computer type connector, or remove it completely and solder the power cable directly to the amp.
Does any one know if the r-1220 uses the same Marantz 2215b parts?
No. They are similar but not identical and many parts are different, starting with output transistors. Service manuals for both receivers are available (for free) on hifiengine, you can download and compare them for more details.
Glory to Ukraine!
Thanks a lot for this very thorough review! I may buy Valcos if I don’t find cheaper options, but then audio quality would drop likely which again makes Valcos a good option. Did you feel that they pressed too much your ears? My current JBL live 500BT are horrendous at how tight they are.
No, the comfort is actually quite good considering the earcup size, and they don’t press too much IMO. Haven’t tried the JBLs so I can’t compare, but Harman/Kardon are different brand, same company, and I couldn’t wear those for more than 30 minutes.
Oh, I understand. Would you say Valcos are the best headphones for the price in terms of audio quality (I listen to mostly EDM and rock)? Doesn’t matter which mode is on. Are Sony WH1000XM4 a lot better (worth paying 80 € more?)?
Don’t know if Valcos are the best headphones for the price, I haven’t tried all headphones in this price range. I’d say they’re good for the price.
Sony WH-1000XM4 – I havent’t had the opportunity to try them yet. I know they have a bunch of cool functions the Valcos don’t have. I only compared the Valcos with Sony WH-1000XM2. I preferred the Valcos with electronic music, the Sonys with rock.
What a great guide!
I have noticed that some similar switches online have a maximum recommended speaker wattage, usually 100watt, do you think your unit has a similar limitation? Is it dependant on the switch itself?
It could depend on the current rating of the switch itself (I used a 10A switch, some switches have a lower current rating), maybe internal wiring if it’s really poor quality, possibly additional circuitry like impedance matching circuit or dummy load resistors (that some tube amps need to run safely while not connected to speakers).
Comparison with Sony WH-1000XM2 was a bit silly – they came out in 2017, and at the time of writing would be cheaper than Valcos, if availble. Two generations newer WH-1000XM4 were available at the time of writing. Also, Sony price rapidly decreases after release to around 200€, with the latest model WH-1000XM5 now selling for about 260€.
Interesting review, but misleading if the reader doesn’t know the actual prices of headphone market.
We’re an independent project without an unlimited access to free headphones. I decided to compare the Valcos with what I could get access to. If you’re nitpicking, the Harman headphones are even older than Sony WH-1000XM2 🙂
As for the Sony WH-1000XM2, they were still available at the time of writing (along with WH-1000XM3 and WH-1000XM4), and 2nd hand WH-1000XM2 are still available now. Even at 200€ they are a bit more expensive than the Valcos, the sound signature between these Sony models (XM2-XM4) is fairly consistent as is the form/design, comfort and battery life (according to description, the changes in the latest WH-1000XM5 are quite significant and not necessarily for the better when it comes to sound and comfort), and of course newer Sony models improve/change additional features and gimmicks. That is why I believe my opinion on the Valcos vs. Sony WH-1000XM2 extends to the newer Sony models as well. If someone wants these additional features, app control etc. they should go with the Sonys – and then compare the available models and decide which one has the best combination of features and price. If these additional features are unimportant and someone wants headphones that offer good sound over BT, basic but decent ANC, better battery life, and prefers a more lively sound – the Valcos it is.
Yes, many headphones are offered at decreased prices some time after their release, and even cheaper 2nd hand. That goes for Sony headphones, but also for the Valcos (originally €169, now also available for €147 from Thomann). This is obvious and I strongly advice my readers to avoid buying the latest products before their prices inevitably drop to a more acceptable level (unless the original retail price is really good, which is rare). Plus, a product that was €300 on release and is €200 after the price decrease is still more expensive than €169 or €147 🙂
The original cable is 2×1,5 mmp with a 16 A plug and a thicker socket at the other end ( also Figure 8 type), was delivered in package when new. Conventional F8 can be used. You will not drive the amp to that extreme to melt it ( and 2×0,75 can handle up to 6A). I put radiators to Q651-654 to avoid burning the board. The amplifier is good, driving heavy speakers. It can drive speakers , which other amps can not. Sound is good, but is more centered to power . Phono section is quite good ! So if you have a PHONO , with MC, this amp is a good choice !
I wonder if the wired performance is raw output to the elements. Thus, you could fix it by having a calibrated equalizer in between.
I recently did this with my Logitech computer speakers, which are notoriously boomy, and they are actually almost nice when adjusted.
It is and you could. That’s exactly what the DSP does in the active (BT) mode. Wired mode is either completely passive, or with the signal going through the ANC system (depending on whether ANC is on or off). You could use EQ in both scenarios, although it would probably have a better effect in the passive mode (ANC off).
I personally prefer headphones that don’t require correcting with EQ, which is why I don’t use the Valcos in wired mode for music. Actually the only time I do use them wired (with ANC on) is to watch movies when travelling by plane/train.
I would just like to know if Warfdale Diamond 9.1 speakers would be compatible for my Denon PMA 250SE please? Or would the Q Acoustic 3020i be a better option? Would I be right saying the Warfdale’s would be better for base?
Any information would be appreciated.
Unfortunately we haven’t heard either of them. That said, we did review Wharfedale Diamond 8.1 and hated them fiercely, they were among the worst speakers we used. Q Acoustic 3020i have good reviews, including how they handle bass (considering their small form) and their frequency response looks better (to me) than that of Wharfedale Diamond 9.1. But this is all guesswork, it would be best if you could listen to both before buying.
Hi Where do I find an FM and AM antenna for my Marrantz 2250-B ?
Standard external antenna will do (try online stores/auction sites if you don’t have a brick-and-mortar electronics store in your area). The only thing is, the cable should be terminated with bare wires, not a plug. If the antenna has a plug, you can simply cut it off. For FM, even a piece of wire can be used as an antenna.
I’ve just been given a Sony tuner as described. It’s in perfect condition. One daft question and please excuse my ignorance but I can’t find a suitable lead to get the power from an amplifier. It’s just the AC in socket.
That depends. If your amp is the matching Sony TA-1055 international version (for 110/127/220/240 V, like ours), to power the tuner you have to connect it to the wall AC outlet (just like the amplifier). If your amp is 120V only US version, you can connect the tuner’s AC lead to the amp’s AC OUTLET socket (make sure that the tuner is ether a US 120 V version, or if it’s an international version select 127 V with the jumper on the rear panel).
Generally in some systems you can power the tuner directly from the amp and sometimes even switch the entire system on/off with the amp’s power button. For that to work, the amp would have to have AC out socket(s). The US version of Sony TA-1055 has such a socket, the international version does not.
If you have a different amp, let me know the exact model and version – and I’ll have a look.
I disagree with this sentence:
The technology of building loudspeakers and their drivers has been developed considerably since the 1970s and even relatively cheap new speakers can have a decent sound, while a large part of vintage speakers are nothing special to plain bad.
Maybe you’ve never listened to a pair of Grundig, or Braun, or Advent speakers from the 70s? These are from the 80s and I tell you that compared to a couple of Harbeth 30, much more recent, I sold the Harbeths and kept the JBLs
I did, and I agree that some vintage Grundigs and Brauns (and speakers from other manufacturers) are good (and some are great). But those that are good are not that easy to buy and tend to be expensive. It is much easier to find relatively inexpensive good sounding speakers designed and made after 1985. A pair of Quadral Tribuns from the late 1980s costs a quarter or less of what JBL L96s do. You can even buy floorstanding Quadral Aurum 7s for much less than JBL L96s, and those are in a different league. Same goes for smaller speakers. Mission 760i will outmatch any similarly priced small speaker from the 1970s, and many that cost much more.
I own a NAD 160a. The needle of the tuner is broken and (horribly) fixed by the previous owner. I would like to know how the needle fixation to the string meganism looks like originally and which bulb is used for lighting the needle. Is there any chance you have some pictures of that parts?
Thanks in advance,
Have a look at the penultimate picture in the gallery ( http://audio-room.net/wp-content/gallery/nad-model-160/NAD-160-DDSCN9935.JPG ). This is the best I have. The bulb is inside the pointer (needle) fitting, right above the pointer, supplied by the two black wires.
Thanks for creating this very useful article.
I’m wondering if there are any brands/models/types of the switches that would minimize degradation of SQ? Maybe you could recommend a certain type of material they should be made of?
And the same goes with binding posts – should they be, let’s say copper or does it even matter?
Thanks in advance
I don’t have recommendations for specific brands of switches. The switch should be sturdy, have sufficient voltage rating and be a break-before-make type.
Binding posts – just like with binding posts for amps and speakers, in theory gold plated are better, in practice the difference is rarely (and barely) audible, convenience is what matters most. Copper in not ideal for mechanical parts like binding posts, not hard enough, breaks and corrodes too easily.
Internal wiring – OFC copper is better than, say, cheap CCA wires, and I wouldn’t use wires thinner than 1-1.5 mm. You can use thicker ones, but on such short sections it’s not really necessary and thicker wires are more difficult to solder/connect to posts. I don’t use fancy wires (silver, etc.) inside either because again, with very short sections I don’t think they would make much difference.
Your post save me. Thanks a have the same story, this time waiting for Rondo Speakes 🙂
Fantastic, thanks for the review and the “nudies” !
You mention that the amp’s earliest version (the one with the extra piece of metal each side of the fascia) has a IC-based phono input. I find that surprising, as perhaps discrete may have been cheaper in that early period of semiconductors? Which model IC is that, and is it DIL or DIP package?
Great site, will take me days browsing the many other pages you posted…
Sorry for the stupid question, i just realize there also is a photo of the phono stage with that metal shield removed …
No worries. In case the marking is not clear enough, it’s a Sony CX 0461 IC. Quite hard to find if it dies, unfortunately. With some tinkering, 2x OPA604 op-amps can be used as replacements (a guy on Audiokarma did that in a TA-1150)
I know this post (and these speakers) are quite old at this point but I have to agree with this revisit.
I found these speakers in our nearby electronics recycling container (foreshadowing) where people can bring old electronics that either no longer work or they do not want to simply use them anymore for some reason. Me being kind of a tinkerer I like to try and repair things so picked these and ALSO remembered the same that these were quite well regarded in many magazines/websites at the time of release.
I have really old bookshelf speakers from Sony that are so old they are actually made in Europe. I got those years ago also for free so I was like that “these cannot be any better than those Wharfedales” and boy was I wrong. I plugged them in and was like “ehhh, these must be broken” and was immidiately going to find more information thinking I was wrong about the old reviews. Seems like my memory was correct and these are just plain bad.
Bass was lacking and dull, no punch in it at all and even when trying to boost it didn’t help. But the highs were the worst! Without EQ you could barely hear them compared to my old (and much older) speakers. Even when boosted to the max in the EQ it was like they had still a thick curtain over them. I was so disappointed.
Needless to say those Wharfedale’s are going back where they belong – recycling. If we’re lucky they get used in their afterlife to make some actually decent speakers but not sure if it is possible even then, haha!
I think something went very wrong with the crossover design in these speakers. If I ever come across another pair, I might tinker a bit to see if they can be improved.
Since you already have them for free, this might be a good opportunity to try a few things yourself before you dispose of them. I would start with checking electrolytic caps in the crossover. In one of the pairs I had the caps died and those sounded even worse, might be the case with your pair. Not that they sounded good after I replaced the caps, bud certainly less bad 🙂
Bass could probably be improved a bit with different damping inside the enclosures and/or closing the bass port (partially at least).
what is the 2.5mm mono jacks size length and width.help me thanks
The information you’re asking about is in the main article.
The space to fit the new socket is 6 x 6 x 15 mm. Any socket that size or smaller should fit. A socket that has larger dimensions will not fit.
You can use a 3.5 mm jack socket if it is 6 x 6 x 15 mm or smaller and fits the space. I used 2.5 mm because I already had a few cables with 2.5 mm plugs.
You can also solder the cable directly to the internal wires in the headphones, or even directly to the drivers, if the cable you use is thin enough to run it through the existing hole or you drill a bigger hole. This is the best solution if you don’t need a detachable cable.
The sound with most decent quality wires will be pretty much the same as with the original wires. If you use a very high quality wire, it might improve slightly. If you use a poor quality wire, the sound will get worse.
The thing that will improve is the connection – no more intermittent sound.
only 2.5 mm SMD Headphone Jack Socket?any 3.5mm socket fit?
any 3.5mm socket could fit? The sound might change better after you replaced?thanks very much
The information you’re asking about is in the article.
I found a high quality socket. Its a 2.5mm ,CUIdevices product.I like the gold plating,but length only about 11mm.I doubt Its unstable.The terminal of socket is Ti copper.Anyway,I decide to try .
If the socket is smaller than the space, you can always add some filling material inside to immobilize it, or even glue it in. Should be easy enough. Good luck!
Hi, I bought this unit from a seller on eBay as a spares or repair purchase hoping I could get it repaired when I opened it up the board was split 8n a few places and burnt making it impossible to repair, I also own the SU-V900 Mono Amplifier, 2 x SU-VX700 1 faulty, 3 x SU-VX 600, SU-V660 and finally A SU-C800U Control Amplifier and the SE-A800S Power Amplifier, should I take the 15,000uf Capacitors and transformer’s from the faulty SU-VX800 and buy 2 more 15,000uf Capacitors and get a professional engineer to fit and test them in the SU-V900 as I saw I guy 9n YouTube proposing to do the same thing with one he bought, I could then sell all but the 800s and a couple of 600s as I have read a few reports about how good this model is due to the protection being removed by Technics at the design stage.
Where are you as I need a servicer and maintainer once in a while.
Sorry for the long message.
You seem to have quite a collection of (faulty?) Technics amps. Sorry to hear about your SU-VX800 being terminally damaged. My advice would be to take it and the unit you want to donate its parts to to an experienced technician (or at least consult with one, have him review the service manuals/schematics) to confirm the transplants would be doable and make sense. Not sure if I understand your idea correctly, but if you want to replace parts in your SU-V900 with SU-VX800 parts, you’d have to find another set of SU-VX800 caps and I guess keep the SU-V900 transformers (you definitely want the same parts in both channels in a dual mono amp; SU-V900 might actually have more powerful transformers – each transformer feeding a pair of 12,000 uF caps – than SU-VX800, where 2 transformers feed one pair of 15,000 uF caps, so I’m not sure replacing transformers is a good idea). Also, I’m not sure if replacing SU-V900’s original 12,000 uF caps with U-VX800’s 15,000 uF caps would make a significant change (if any).
I’m in Warsaw, Poland.
thanx for the info. Got a question: whar specs should the switch have?
thanx in advane
The switch I use is 4PDT 10A 250 VAC. But a 2A switch will be OK too, I prefer a bigger one because it’s easier to connect wires to it.
Nad 160 main power transformer
My main power transformer has come to its end. I cant seem to find a lot of data about it on the net so I am wondering if, perhaps you have an idea how to find one.
Your best bet would be to find a damaged NAD 160 with a working transformer and buy it for parts. Alternatively, you can try to find a company that makes transformers to spec and order one. They should be able to figure out the voltages you need based on the schematic diagram (available for both NAD 160 and 160a) or the original transformer. Or look for a workshop that repairs transformers. The availability of such services will depend on your location so if you don’t find anything locally, search all over your country – it might turn out to be cheaper to send your transformer for repairs to another city than to order a new one or buy a damaged receiver for parts.
THX a lot for all the info. I am looking all over the net and hoping to find it. Now I will start to look if there is a repair workshop in the area. I hope to fix the NAD because it realy is a beautifull sounding peace of vintage equipment.
I would like to add that the VMK25 new headband adjustment system makes the headphones fit to small heads way better than VMK19 or VMK20. VMK20 keeps falling off, but VMK25 stays firmly in place.
Thank you for this information. We did not have an opportunity to check how they fit smaller heads, so that is good to know.