Hi,

I'm still checking for some noise issues in my system, and recorded the output of my Buffalo III + IVY III with my EMU 1820M sound card.

You can see on the attached pic, what I got: pretty clean, but there're several spikes at 22Hz, 44Hz, 66Hz, 88Hz. They're at a very low level: -125dB, recorded with +4dBu input setting. I'm using an 8ch setup, this is a single output, with IVY III gain resistors adjusted to 3kOhm as the integration guide says. It's surely not the sound card, the self-noise recorded looks just a tiny bit less noise floor, but no spikes at all.

The question is where could this come from? I do expect noise here, but these peaks I'd like to get rid of. Any idea, what can be the source?

Thanks,
igy