[Mantrasolo]

What would cause a mixer to constantly feedback, or have a feedback sound running at all times?
I just borrowed a 6 input mixer that my drummer found. It's a used Yamaha, and as far as I can tell only 1 of the 6 1/4" input works, but all of the xlr input works (it has 6 of those too). It runs on 2 fuses and is plugged up into the wall output.

So I tried hooking my xlr mic up in each one of the inputs, and there's this medium frequency sound just looming .... beeeeeeeeeee..... like a phone line. When I turn it down, it gets quieter, duh..etc.
The input itself works, it's just annoying with that noise.

The way I have it setup is: Mic -> Mixer out via Left and Right "Speaker" outputs into my Amp modeller line ins -> into the computer.
There are left and right output that's called "Amp", but the input itself is missing, it's just the hole...Weird, I know. Dunno if that output would make a difference...


Anyway, any ideas as to what could be causing it or what I could do (short of throwing it out) would be met with extreme gratitude.

Edit: Using instrument cables.

This post has been edited by Mantrasolo: 16 November 2009 - 09:16 PM

[igorski]

Perhaps there's a send/return opened ? Causing an 'empty' sound to go into a return which keeps resending it will cause a great ruckus. Then again the phone line description is throwing me off. Are you sure all the phantoms are off ? Some mixers send phantom power over jack inputs as well as the XLR inputs...

[Mantrasolo]

...I don't know how to turn the phantoms on and off. I am providing a picture to show what I'm working with.

The 1/4 inputs (located on the front side, under the channel knobs) are not working except for channel 6, unless they are turned off somehow. I don't see a on-off button for the channels. I have messed with the R-L buttons (the white and blue ones) but that doesn't "fix" anything.
But the channels aside, I can't figure out about the "beeee...." sound. Like I said, cannot see any buttons to turn the mics on or off. What's the trick? It's my first time even touching a mixer! *blush*