Not sure if I have a technical problem or not

Benjamin AM · Joined: Nov 04, 2010 Posts: 83 Location: Boise

Hello,
I was inside my homemade modular system the other night rearranging a few things and I noticed when I turned my amplifier to maximum volume , my oscillators seemed to create a bit of noise on the ground(So I think). To isolate this "problem", I unplugged all of my other modules except one oscillator and one VCA. The oscillators audio path was not plugged into the VCA. The VCA was then plugged into my amplifier so I could listen but I also took the amplifier signal and sent it to an oscilloscope. When the amp was cranked up to 10 and the two modules plugged into the power bus directly next to one another, I noticed an audible oscillation(could be modulated by front panal voltages). At this point, the noise appeared in the form of a ramp wave on the scope at .02 V per division setting. When I moved the VCAs power connector away from the VCO on the bus the noise severely dropped.
I am curious if this is normal. Afterall, the amplifier was crank to a level at which I would never play it because the synths output is the standard 10V pp. I would like to solve this problem if it could lead to more problems down the road
Thanks

Mongo1 · Joined: Aug 11, 2011 Posts: 411 Location: Raleigh NC

It doesn't sound like a big issue to me- amplifiers are great at taking little things and making them bigger, and if you give an amplifier any sort of path from it's output to its input it becomes an oscillator.

I'd say just leave it alone unless it manifests itself under normal conditions.

Gary

(BTW - when I read your post I thought of that old Henny Youngman joke - A guy walks into the doctor and says "Doctor - it hurts when I do THIS." - the doctor says "Well don't DO that")