Taco,
I am not sure that the four power supply wires plus earth ground wire are absolutely necessary to reduce ground noise, but I figured it couldn't hurt. If I get a chance this evening, I'll jumper the supply caps on the power supply block and see if any hum appears. If you run with a balanced input, I expect that where you connect wouldn't matter much, since the common mode rejection of the amplifier should be good enough to deal with hum on the ground line. On the other hand, maybe there are large enough currents. Until the absolute DC offset at the outputs settles down, you could be running as much as 300mA to ground.
I haven't settled on an earth safety grounding scheme. Since I do connect the plus/minus supply ground in the amplifier chassis instead of the PS, I am almost certain that I have to run a separate wire for the safety earth ground to avoid a ground loop.
Jeremy
I am not sure that the four power supply wires plus earth ground wire are absolutely necessary to reduce ground noise, but I figured it couldn't hurt. If I get a chance this evening, I'll jumper the supply caps on the power supply block and see if any hum appears. If you run with a balanced input, I expect that where you connect wouldn't matter much, since the common mode rejection of the amplifier should be good enough to deal with hum on the ground line. On the other hand, maybe there are large enough currents. Until the absolute DC offset at the outputs settles down, you could be running as much as 300mA to ground.
I haven't settled on an earth safety grounding scheme. Since I do connect the plus/minus supply ground in the amplifier chassis instead of the PS, I am almost certain that I have to run a separate wire for the safety earth ground to avoid a ground loop.
Jeremy
Taco,
I tried several different grounding schemes, and nothing I did caused any audible hum.
1) Jumpered the two capacitor banks in the PS, making it a three wire connection - no difference
2) Taking the safety earth ground from the PS or directly from the amplifier chassis - no difference
3) Variations of the above themes - no difference
The test amplifier I mentioned earlier with a Zen V4, Aleph-30, and AX-60 does suffer from ground loops when the AX-60 is selected. That amplifier is stereo and not dual mono. I had to share the power supply between both channels to make switching between amplifiers easy. That is likely the problem.
Jeremy
I tried several different grounding schemes, and nothing I did caused any audible hum.
1) Jumpered the two capacitor banks in the PS, making it a three wire connection - no difference
2) Taking the safety earth ground from the PS or directly from the amplifier chassis - no difference
3) Variations of the above themes - no difference
The test amplifier I mentioned earlier with a Zen V4, Aleph-30, and AX-60 does suffer from ground loops when the AX-60 is selected. That amplifier is stereo and not dual mono. I had to share the power supply between both channels to make switching between amplifiers easy. That is likely the problem.
Jeremy
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