Official M2 schematic

I changed the grounding schema at my M2 and no change at all..Now I am in doubt thats even a GND problem! Maybe some interference whit toroids...???
I attached the pictures. As you can see the signal GND, speakers GND and PSU GND are mated at one point! The yellow wire leads to CL-60..

M2-S1.jpg

M2-S2.jpg

M2-S3.jpg
 
Last edited:
The input transformers look to be far enough away from the toroids. I would not think that is the problem. Is there any way to move the PS on one channel more toward the center of the case to just see if it makes a difference? I know it is DC but they are closer to the transformers than I would like. Just for a test you might want to lift the chassis ground to see if it makes a difference. Just temporary mind you.
 
Last edited:
The input transformers look to be far enough away from the toroids. I would not think that is the problem. Is there any way to move the PS on one channel more toward the center of the case to just see if it makes a difference? I know it is DC but they are closer to the transformers than I would like. Just for a test you might want to lift the chassis ground to see if it makes a difference. Just temporary mind you.

I did what you suggested but didnt make any difference...
 
caps too near...imo
PS spotted hidden inductance....

The PSU is clear of any special artifacts. I get around 18mV of ripple on oscilloscope.
I removed the bypass caps at the end and noticed the amp sound better but the hum is still present on one channel a little bit more than on other. I also noticed when I powerd the amp on one of the toroids did hum for 1 minute or so then it settled but its the same hum I hear in spekaers...
 
I chased a hum on my first FW build on one channel. Never did find it. Hums can be frustrating but there is an answer somewhere. I replaced the Aleph 30 boards with something else but the hum was never obtrusive while listening to music,the reason I did not spend a lot of time digging into my problem channel board. You may want to try a shield for the input transformers. It is not hard to improvise and make one.
 
The PSU is clear of any special artifacts. I get around 18mV of ripple on oscilloscope.
I removed the bypass caps at the end and noticed the amp sound better but the hum is still present on one channel a little bit more than on other. I also noticed when I powerd the amp on one of the toroids did hum for 1 minute or so then it settled but its the same hum I hear in spekaers...

You may want to swap the transformer wires from one channel to the other and see what happens.
 
I changed the grounding schema at my M2 and no change at all..Now I am in doubt thats even a GND problem! Maybe some interference whit toroids...???
I attached the pictures. As you can see the signal GND, speakers GND and PSU GND are mated at one point! The yellow wire leads to CL-60..

View attachment 540750

View attachment 540751

View attachment 540752

Try to keep away those (power) wire, caps etc. from the RCA terminal. That can cause a lot of funny noise, buzz etc.
I do not say 100% that is your problem just to make sure.... :)