Preamp

[datanasov]

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

 

[Pascal]

Datanasov,

Please check the URL. Browser cannot find it.

Pascal

 

[tvi]

<a href="http://www.fmi.uni-sofia.bg/fmi/statist/dimitar/"><b><u>fmi</u></b>.uni-sofia.bg/fmi/statist/dimitar/</a>


James

 

[Pascal]

Thanks James.

Pascal

 

[Helix]

could you draw a schematic, the pics arn't much to go on.

 

[datanasov]

The problem is not in the schematic. I thing that the problems are in wires. The signal grownd is in one point.

The idea is almost the same as the preamp project of Rod Elliot.

Also, there is a hum even in pasive mode, without any cirquits.

 

[Helix]

have you followed the rules of only haveing ONE ground point, a star type ground were all the inputs/outputs etc run off. also check all the connectons are being made properly. If you are getting hum in passive mode, this can only be the cause.

 

[datanasov]

thanks a lot, I'll check it