I finished my BSIAB II tonight but it seems--depending on how i use the trim/vol/ and all other adjustmnts--that theres a high pitch noise ..I can tame this sound if i bring the volume down but i lose gain.. Thats the same with the gain pot. If i max that out the squeeling high pitch sound it back..But i can get rid of it all one again if i turn the trim pot to the left, but then --once again i lose gain and some volume. I can also get rid of the high pitch sound if i turn the tone to the left(more bass--less high's--) but then i lose a little clarity and harmonics---How do i max this think out without losing and volume or gain/highs/ and harmonics.?

Each time i set it i can get it to sound different/good but i know this thing doesnt have to lose anything in the process..

It sounds like you're dealing with the same issue I'm discussing in the electronic switching thread...
http://www.diystompboxes.com/sboxforum/viewtopic.php?t=24582

Since the circuit is rather high gain the signal coming out to the input jack is causing interference with the input jack wires, feeding some part of the output back into the circuit input, and causing that feedbacky squeal. Before you go as drastic as changing to non-true bypass switching, try cleaning up your wiring job as much as possible. Use the shortest wires you can from the input and output, make sure they don't cross or run along one another, and possibly switch to shielded wiring for the input and output wires. Maybe in the case of the BSIAB that'll take care of it...

Thanks --ill givr a try--I know my wires are a little long..Maybe its just the trim pot adjustmnt..How do i know if that is set right? It goes from a little gain --no squeel to the other end with high gain and squeel..

thanks,

jim

Quote from: jimbobThanks --ill givr a try--I know my wires are a little long..Maybe its just the trim pot adjustmnt..How do i know if that is set right? It goes from a little gain --no squeel to the other end with high gain and squeel..

thanks,

jim

The trim sets the bias for the third gain stage. I set it by ear. It will either sound gated and blatty or sound good. You can also find a range to where you can reduce the gain and still have it sound smooth, but that's it
The squeal is, as was noted, from oscillation. The third gain stage helped greatly in reducing this. I haven't had any problems with it. First thing to try would be reducing the wires.

Inoticed i was using a 500kl instead of the 500ka pot for gain. Not sure if that would make any difference.

Quote from: jimbobInoticed i was using a 500kl instead of the 500ka pot for gain. Not sure if that would make any difference.

That would have no bearing on the oscillations, only in the taper, or transition in gain from one end to the other.

Ok ..i did it and it sounds great. Ed--you did an awsome job at this!!! I got rid of the squeeling by taking turning the tone a little towards the left--bass side--and listening to the sweet spot on the trim pot. There are a few diff things that can be done to get rid of that sound and as many different great sounds to be found as well. I REALLY like this better than any Tube Screamer ive built as well as most of the distortions ive built. It just sounds so much better w my amp. !!!!!

BSIAB II --totally recommended!!