• Welcome to ADA Depot - A Forum To Support Users of ADA Amplification Gear.

mp2 output problems

Started by gb, April 11, 2014, 03:26:57 AM

Previous topic - Next topic


Well R that's good thinking but no that's not the problem.For some reason the signal is not comming trough the FET altough it should.


Hey MJMP, pls pardon if I ask dumb questions BTW or stuff you've already thought through.
Does the signal come through the FET when its not in the ADA circuit ? (i.e. isolated)
If FET is good, what could change its behaviour ?? I'm a bit out my league here, my basic understanding is it's operating as a switch (on/off) ??
Also, they used to work fine (and still do in many MP2s) so where's this going...
Maybe the solution is a new switching circuit ?
Cheers R
Studio Rig: Stuff; Live Rig: More Stuff; Guitars: A few


Hi all,


After years of investigation, questions, etc. I met a guy here in France and in my town (Nantes) who repairs guitar amps, in fact he was a friend of mine years ago and we losted ourselves until all those years. Recently, in decembre, we met us in a music store in Nantes and we began discussing of what we did all thoses years, so he began to say that one of our friends is now reparing tube amps, preamp, etc... So I talked about the issue on my MP2 and he accepted to see what he could do.

After 2 months of investigation and test, he finally solved the problem, so he changed ALL the transistors and diodes on the compressor circuit and now my MP2 is sounding like the first day!!! He said me that the initial transistors were not good quality so this was the source of the problem and very difficult to see.

Here is his site for people who wants to contact him : http://pms.elec.free.fr/topic/index.html




Hey cheachwood, woww what great news  :whoohoo!: and thanks for the contact !!
Now we/you can get on with MP2 tone/patch/patching to get it sounding the best it can for you.
Cheers R
Studio Rig: Stuff; Live Rig: More Stuff; Guitars: A few


Nice!! Do you happen to know if he used replacements and if so which ones?


Awesome news! what replacement parts did he use?


Quote from: RobbHell on February 09, 2015, 10:36:04 AM
Awesome news! what replacement parts did he use?

I don't know, he said to me that he replaced all the transistors and diodes of the compressor circuit board.
I will ask him by mail and keep you in touch.



Hi guys, unfortunately one of my MP2's seems to be having exactly the same described behavior, as showcased in Gb's youtube videos.

Cheachwood, did you get any answer about the transistors and diodes replacement parts?

I looked around the site you indicated but  :( (bad luck) the workshop is closed until 3 october.


Interesting and annoying trouble-shooting.  Glad the culprit got fixed ;)

Due to this, I just wrote a little essay about basic maintenance and scooping-up electronics:


managed to contact the tech in france and he sent me this

Hello, first of all, please excuse me for my American, I use a translator.
The ada mp-2 repair is quite old and I'm not sure what information I'm going to give you.
As a reminder, I had replaced the following transistors: Q200,202,220,and 221.
I think I have also replaced diodes D206 and 208.
I hope this will help you repair your equipment. I also attach the part of the diagram.

Best regards


what transistors can i use as alternatives for the ones listed ?
they seem to be out of production and i cant find equivalants


Already tried this, didn't help with my MP-2.