BSIAB II

[AndyG]

I built the bsiab and I think it has a lot of potential, but I am getting a irratating sound in the high frequency range and cant seem to get it out.
Any ideas?

Thanks
Andy

[John Lyons]

What type capacitors did you use? The 470pf sounds better with a film/poly cap or even more so a polysterene cap.
Is the noise something that is constant or a fizzle that goes away after the note decays a bit?
The sound should be tight and not have any objectionable noises on top of the notes. 

John

[AndyG]

The kit came from ggg. The 470 pf looked homemade. The sound is allways there.

[Kleber AG]

Have you used long wires from the bypass switch to jacks and board?
Not used shielded wires?

It's a sort of a high gain circuit, it produces enough gain to have feed back problems causing oscilations like a wistle...
So it needs some care about placing, routing, wires, jacks etc to avoid those oscilations.

[HOTGUIT]

Hi AndyG
To cut high freq and add mids and low do that:
1) C14 = 0,1 micro (or 1 micro for more bass)
2) C8 = 1 micro
3) put a resistor between C8 and tone pot's pin 3 (I use 22K but till 100 K can be used. it adds mid freq. and cut high freq)
4) C5 = 560 pico (I use 680)
This mod is NOT mine but I think the owner agrees to share it.
Try it, it solves!!!