ADAM Active Studio Monitor schematic diagrams help

I have a pair of original S3-A's, where one of the two speakers outputs a really loud buzzing sound (max volume, and you can see the woofers retracting!) when activating them. This doesn't happen every time when powering on, but only periodically.
By quickly power cycling the speaker, I can get past this buzz. And once they are powered on without the buzz, they stay that way until powered off.
Any ideas where to look to solve this?

Many thanks!
I had the same thing happen to my S3A B-Side (serial P-6953). Both S3A monitors had been sitting a considerable time. Like you did, I just recycled the power and it has not happened again. While my serials fall outside that known range, I wonder if it should be included in there, too.

I need to emphasize that this may not solve our issues, but there are some issues with these monitors. But oddly enough my S3A Side A is now making that swishy white noise sound that is indicative of the failures mentioned in the quoted thread below.

FWIW, there is a post at another form (not sure of the etiquette posting other forums so...) some years ago about a bad batch of ADAMs. To quote from the other site: (and it was posted by a rep from ADAM so it's the real deal)
There was a batch of ADAM produced (approximately between serial number P-4800 and P-6800) that have a problem.

The short version is that there's too much heat in the box, which can affect the electrolytic capacitors on the filter board adversely. If you open your unit, you'll probably see that they're swollen. They might even be leaking, so please be careful if you go in there yourself.

Those caps need to be replaced. That should take care of it.

All ADAMS in that range will probably eventually have that problem (if they haven't already). How long it takes is mainly a matter of how much use they get, how hot the environment where they're used is, etc.

It's also important to note that at that point, ADAM was using the same serial number series for all their P-5251/P-5252 could have been S3As and P-5253/P-5254 could have been any ADAMs inside these serial numbers will potentially suffer from this issue, not just S3As
Last edited:
ADAM P 11 A UCD service manual

ADAM Audio P 11 A UCD Active Studio Monitor service manual

"P11A (07-07-06).pdf:
Your file of 1.69 MB bytes exceeds the forum's limit of 976.6 KB for this filetype. "

I can send it as email.
Could you please send me a message, as i can't send a message to you, i need this service manual for repair my monitor.
Thanks in advance.
Hi- Many thanks for the A7 schematic. I just replaced all the caps on a pair of A7s which were failing and thanks to that technical file the job went as well as a 34 capacitor replacement (x2) could go… Ugh. I also have a pair of ADAM F7‘s, one of which has a delay on signal sense issue. Is there a schematic for F7 series amp boards available?
You can help others by contributing your shopping list. I think it was not necessary to replace the big ones.
By the way what is "P7" in post 12 should read "A7" ? In this case I will change it.
On one it absolutely was and on the other only the smaller caps failed. But the first one (the bad one) had no paired larger electrolytic within the 20% spec. Plus it is not good practice on any stereo pair input or output device to do work to one that you then do not mirror, don't you agree? Do you want DigiKey and Newark part numbers of what I used? Because I bought what they had and not what I always preferred as they tend to be out of many things these days. I also substituted 105c 'long life' caps where possible- but mostly the improvement came from using an actual name brand where ADAM used cheap Chinese ****- which need I say is not an impressive solution given the boutique nature of the overall Adam monitor reputation and design...

Since you are obviously legitimately asking, the monitors remained on for many many years at a time (perhaps 7 years), and were in bypass/sleep mode unless used, however, I wonder if the bypass amplifier signal sense cap failed on one side and caused the amp to generate more heat than its counterpart? Also I am not as good at understanding schematics as I am at repairing electronics, so I might not truly understand the A7 sleep mode. Perhaps it doesn't really every go into power saving mode like for instance the F7...
Last edited:
I do have a favor to ask. I don't know which of those three plugged (factory EQ adjustment) pots controls which EQ function on the A7. Their setting are pretty much presently meaningless as I had probably dislodged their factory settings by accident during work, and even so the capacitor values have subtly changed due to repair. If you can tell me which one controls Room, Woofer, and Tweeter, it would save me a little time dickering with the setup when I put the monitors into an anechoic measurement protocol... Never mind found it: RV1 is high gain, RV3 is low gain and RV3 is bass boost...
Last edited:
Hello guys, I need also schematic for A8X. Couldn't find it on web, but if anyone ever got it, it would be nice to share with us. ❤️

There isn't any cap at the input. Pin 6 goes to the via to the right of R264 (0 ohm link) and down the the black lead to the left of ZD250. On the other side of the via there's a track to another via which comes back somewhere under the chip. I can't find a cap directly connected to pin 6.

(Cables are for attaching the scope)
I have exact same problem on A8X, sub is not working and tweeter is working. I'm trying to find problem, amp board is very similar. It using same TDA8950, and AMP is generally 90% same, just output induction part is little bit different. I check preamp section board, and it sends signal in correct values. I even send signal to another amp from A8X preamp. So, I'm sure something is with amp board 100%. There is no visible damage on it. I didn't check voltage for mode selection on pin 6, but there is only C285 that could be cap in same trace. I'm so confused . I have bad feel that TDA8950 is broken.
Anyway, did you find problem or still searching for it? Sadly I don't have oscilloscope, it would be much more easier. I'll definitely buy an one.:unsure: