motorboating shielding power supply capacitors

If that sounds like I’m nuts you may be right.

I’m not sure why the XLR cables themselves don’t close the loop, given that they’re connected to both units-and the weird thing is that I don’t even have to fully contact the two units with my hand to eradicate the noise-just getting my hand in the vicinity resolves it, and it only works when I make contact on the right side of the amp/DAC-I can grab the left all day and the sound persists. When I open the chassis there is a ground contact on one of the housing screws and I wonder if it isn’t a robust connection, but now I’m getting way out of my wheelhouse. I grabbed my multimeter and touched the chassis of the amp, along with sleeve of both the XLR headphone output as well as the sleeve of the XLR input on the back-in both cases it read a very tiny voltage, so I’m wondering about a faulty or loose ground in the amp. The noise is definitely motorboating, and as I mentioned before it is prominent in the right channel only when the amp is in solid state mode, then it switches to the left channel (a bit quieter) when I engage the tube stages-God only knows what the hell is going on. I hadn’t seen the clip leads before and I’m going to try jumping the amp and DAC together (once I figure out where to do so).

88, thanks again so much for offering your insights.

I tried removing the Bluetooth antenna on the DAC with no improvement. Also, raising the amp up on a riser does not resolve the noise (unless it is positioned three inches forward on the DAC so they’re not evenly stacked).Ĭan anyone offer some possible explanations for this please? I would consider a bad filter cap if it weren’t for the fact that it switches channels and disappears with amp placement. I’ve reproduced this exact same behavior on multiple attempts and I can only get a quiet sound when the amp is not sitting directly on top of the DAC. Strangely, when I move the amp forward about 3 inches so it is overhanging the DAC, the noise ceases. I noticed recently that if I stack the two with the amp on top, I’m hearing a low-grade motorboating oscillation on the right channel when the amp is in solid state mode, and the noise curiously transfers to the left channel when I switch to the tube circuit. I have the two connected via good quality, balanced XLR cables. I own an iFi Pro iCAN Signature amplifier coupled with a Topping D90se DAC.

Motorboating shielding power supply capacitors