Preamp

Hello everybody,

I have one question, and problem ... :)

I've build one preamp based on my oun design.
It consist of one tone control circuit and a volume discrette pot. There is a posibility to swich off the suply and to work in complete passive mode.

So the problem is that there is a hum on one of the chanels, even in passive mode.

I'll be happy if someone can give me an advice about that.

My page is:
www.mfi.uni-sofia.bg/fmi/statist/dimitar