It sounds like an intermittent connection somewhere. A bad RCA cable connection to the RCA input will do much the same thing. Swap inputs and if it were me I would pull both input and output grounds and attache them to the Star ground. Being the noise goes away when shorted I would be mighty suspicious of the RCA input connector.
my feeling is that it is either bad cable before input or cracked pad-track link due to temp diferential...look for that ...it's super hard to spot and no matter how many times you redo the pad resolder it will not go away.
you have 2 choices for this....track the crackle from input to output and once found scrape a bit of track near pad on all pads arround that spot and resolder....second : use brute force method and do this to all pads.
you have 2 choices for this....track the crackle from input to output and once found scrape a bit of track near pad on all pads arround that spot and resolder....second : use brute force method and do this to all pads.
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I tried also the inductor on top version but the buzz 50hz results are the same! Very low volume I have to put my ears very close to the speakers but anyway I can hear it thats the problem! I think the main problem are the two big 800VA toroids witch I cant move farther away from the amplifier boards and PSU.
So the plan is to move the transformers, caps and inductors to a separate chassis so that only the amplifier will remain in this chassis. BUT how long (i know as short as possible) but can they be 1m long I mean the cable from the psu to the amp? And the size of the decoupling caps in amplifier chassis? I have 1000uF 50V elnas available? So I need your advice what to do? Otherwise the M2 sounds wonderful!!!
So the plan is to move the transformers, caps and inductors to a separate chassis so that only the amplifier will remain in this chassis. BUT how long (i know as short as possible) but can they be 1m long I mean the cable from the psu to the amp? And the size of the decoupling caps in amplifier chassis? I have 1000uF 50V elnas available? So I need your advice what to do? Otherwise the M2 sounds wonderful!!!
Copy from our Papa master on Xs amplifier, use PowerCon and 1m cable should be good. Remember that inductor is just a very longg cable. 10mF should be enough but not 1mF. Well you can check what i've done if you think its reasonable.
www.diyaudio.com/forums/pass-labs/166784-pictures-your-diy-pass-amplifier-351.html#post4670010
maybe we could all reason better if you could give us a scope image of the signal that causes the effect you refer....feed the amp with a sine wave for example and get the image of the output.
It is dificult for me to believe that the trafos or caps are doing it...trafos are huge by the way ...why so big ?...half that is plenty.
Anyway that's OT....would be great to see a picture of the offending singal...even better with both channels in simultaneous....
It is dificult for me to believe that the trafos or caps are doing it...trafos are huge by the way ...why so big ?...half that is plenty.
Anyway that's OT....would be great to see a picture of the offending singal...even better with both channels in simultaneous....
Please take a look at post 1008 or link http://www.diyaudio.com/forums/pass-labs/281520-official-m2-schematic-101.html#post4664760
This is the signal i get on speakers. The input is dead queit also when shorting it the signal remains on speakers. Only difference is when I move the toroids away from the circuit I get different modulation and volume.
This is the signal i get on speakers. The input is dead queit also when shorting it the signal remains on speakers. Only difference is when I move the toroids away from the circuit I get different modulation and volume.