GGG Bluesbreaker mod

[tomnottom]

I saw in another post someone said if you lower the value of the 4k7 resistor you will get more gain in the bluesbreaker pedal. There are 3 R2 R7 R8. Which one should be lowered or is it all 3? I know in the GGG ITS8 kit there is one 4k7 at R6 and for the landgraff mod it is lowered to 1k for more gain. Thanks in advance Tom

[Mark Hammer]

Both R2 and R7 will increase gain if reduced in value, though not necessarily in a desirable way, since they will each result in changes in bandwidth because of their interaction with other capacitors.  My own recommendation would be to stick a fixed resistor between R15 (100k gain pot) and pin 2 of that first op-amp.  Try 22k for starters.  That will change the maximum gain in stage 1 from 22.3x to 27x.  That may not seem like much, but you need to consider that this gain will be multiplied by the gain in stage 2 (46x), so even fairly modest gain increments in stage 1 become a big deal down the line.

The resulting change will have no impact on bandwidth or the treble/bass balcne in stage 1.

[tomnottom]

Thanks that is a great idea. I am new to pedal building and sometimes get confused. I am learning. Next pedal won't be a kit.

[Mark Hammer]

Whoop. , I should mention that the added fixed resistor will make it harder to get pristine clean sounds, since it yields a minimum gain for stage 1 of 5.7x, rather than unity-gain as the stock circuit does.

On the other hand, if your search is for more gain, then I think it is safe to assume that you weren't desperately clinging to clean tone.

Still.  If the suggested addition of 22k turns out to be too much dirt at minimum gain, stick a 10k or 15k in there instead.