Preamp question

[Mihkel]

I know this is not related to stompboxes, but I thought this would be a better place to put this thread than the Lounge. Anyway, I found this schematic on the net and I was wondering how (if) could I add a volume control to this?

[Nasse]

I think it is just best to put a volume pot after the circuit, and leave the preamp "fixed gain" design.

This circuit is not suitable for use as normal electric guitar preamp, but I believe you know that

[Mihkel]

Thanks for the reply. Yea, I know that, I'm gonna use it in my acoustic. As for the control, any ideas about the pot value?

Thanks

[Nasse]

I would start at 1 meg or 470k...100k , quess lower values work fine but I am not very much home with discrete transistor stages, with that 0,1 uf cap maybe bass starts roll off with very low impedance

[Mihkel]

I built it, but when the transistor is in its socket, there is a VERY, VERY loud whistle, that only stops when something is said in the microphone. What's causing this?

[Andui]

try poining the mic in the other way than the cab. that could help and you also could turn down the high on your amp a bit