You have a grounding problem. The three types are "not enough ground,"
"too much ground," or "mislocated ground."

To see if you have "not enough ground," just connect a wire from the
chassis of the mixer to the chassis of the Delta1010. If that solves
the problem, then you can fix it "for real" by figuring out why you
weren't getting a solid ground connection in your audio cable.

To see if you have "too much ground," you need to disconnect a ground
wire someplace. The safest way to do this is to use an audio cable
with its shield cut at one end. It's not considered safe to lift the
ground on the power cable.

If neither of these is your problem, then you're in a tough spot
because you can't do much about the 3rd possibility.

My suspicion is that the equipment is expecting to see a solid ground
connection through the power cable, but that you have inadvertently
lifted that ground by using a 220:110 stepdown transformer that is
ungrounded.

ulysses


In article m, me
wrote:

This is so annoying. The only thing I have on are the computer and mixer
(and hence the power transformer I use here in Germany for my US gear). The
mixer's first two channel inserts are connected to delta1010 ins1/2. There
are two mics coming into those channels, but even with the mic cables
unplugged and trim all the way down, the delta monitor shows the following:
www.guitar-dreams.com/misc/delta1010problem1.jpg

If I unplug the inserts it goes away. The recorded audio is

http://www.guitar-dreams.com/misc/de...0waveform1.mp3

The spectrum analysis shows

http://www.guitar-dreams.com/misc/de...0waveform1.jpg

So, if I take the unplugged insert and touch it against any jack on the
mixer, the input level on the delta then rises back to the level shown in
the picture above (first one). I then touched it against one of the screws
that is holding the delta on my rack and suddenly both delta ins 1/2 input
levels dropped down. Not completely though.

There is still a waveform there

http://www.guitar-dreams.com/misc/de...0waveform2.mp3

with a similar specal analysis

http://www.guitar-dreams.com/misc/de...0waveform2.jpg

Any idea what is going on here? In both cases, the spectral peaks are at
50Hz which of course is no coincidence. I would be tempted to think it has
something to do with the step down transformer I am using on my US gear. But
in this apartment, if I turn on a stereo, I hear 50Hz coming through the
speakers regardless of the transformer.

I feel like I am just doomed in this apartment. I hear 50Hz everywhere. The
fridge, etc,etc.