Official M2 schematic

I built the M2 boards and mounted them on the test heatsinks to make sure they worked properly. In my music room they were quiet without the shield. During final assembly on the workbench, there was low level noise from the computer sitting just a few inches away. I installed the shield and grounded it. When I turned the amplifier on again it was absolutely quiet.
Grounding the shield was something I copied from Zen Mod's Papa's Koan build, his M2 clone, since I had never before used mu metal. After Jeff posted his comments above, I took the time to read about it and agree with him. I stand corrected, grounding the mu metal shield is not necessary. I am sure it does not hurt, so I am not going to take apart my M2 just to remove those grounding wires.
 
Experimenting last nights with M2 coupling caps and i was sceptical about any difference.
Real situation tests that was clearly audible.
The same 2 songs with strings, accordion, piano , acoustic bass , drums and the voice i do play maybe 50 times or more.
Stepped attenuator at the same precise volume level.
7 different types of caps was soldered and de soldered.
Not all show on the photos , specialy bulky paper in oil etc.
Conclusion : passive is important if you care about colorations of recorded sound from the passives components.
Caps changes was like less or more subtle equalisation. That only caps so i take care about semiconductors test next time.
Thanks to Mr Pass.
Was intructive experience after intellectual reads of many articles.
Truth of the music from my actual audio system.
 

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diyAudio Editor
Joined 2001
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Yes, the UMS is great, even if I invented it myself!

It allows you to bolt output PCB's right to the drilled and tapped heatsink diyAudio chassis!

Sneak alert! IF people wanting UMS boards are patient their dreams will be answered!


I am still waiting for the answer to my question regarding the dimensions of the board. Do the mounting holes and mosfet position fit the UMS mounting standard? if they do not then I am not interested I this board.
 
[
Sneak alert! IF people wanting UMS boards are patient their dreams will be answered![/QUOTE]

If this means the store will be carrying M2 boards, great news. I have often wondered why the store would not want these boards being the M2 is such a wonderful amplifier. Any time Nelson is gracious enough to share one of his designs the store should stock boards. Good for store, good for diy'ers.
 
Whit:
- 2x M2 boards 2mm 70µm UMS compatible
- 1x Power Supply Board 2mm 70µm
- EDCOR PC600/15K
- transformer shielding
- all components (ELNA, WIMA, VISHAY/DALE, PANASONIC, BERGQUIST, and so on...), including 2x 60000µ capacitor bank and 8x HEXFRED TO247

Whitout:
- Main transformer
- Enclosure,
- paired JFET
- RCA or binding posts

for 250 Dollar without postage?

JP