tips to remedy VOLUME DROP - Divided Octave (Mutron Octave Divider) by BYOC

[half_smith]

Hey gang,
I'm back inside my Octave Divider from BYOC.
http://byocelectronics.com/dividedoctaveschematic.pdf

Pedal works great, but my volume drops a lot when engaged - I have to bend down and pump up the signal from my clean boost to compensate.

Can anyone offer help as to what I can do?

Thanks!

[antonis]

Make R101 1M, R2 470k - 510k, R3 470k and D1 Si ..
Generally, deal with input stage..

[half_smith]

Thanks Antonis, I'll try those changes!

In attempting to understand your rationale,
Would those changes be affecting input impedence? or the gain of the first Op Amp?

[antonis]

Both..

R101 & R2 affect input impedance..
R3 affects gain and D1 affects (semi)clipping threshold..

[half_smith]

I totally understand! 

[antonis]

I should point out that particular pedal isn't the most mod-friendly one..
(even if you skip from one building block to another..)
e.g. there are quite a few signal voltage dividers without an "obvious" reason..

[half_smith]

I made the changes you suggest and there is a noticeable improvement.
Still really drops when I engage the "Bass Only" side... maybe there's something else that can be done on that particular section?

That board is really tight and I am lucky I didn't break it!
It's also damn near impossible to tell what is what on the PCB because the documents and the board are only labelled in part value not R1, R2, R3 etc...

[half_smith]

Make R101 1M, R2 470k - 510k, R3 470k and D1 Si ..
Generally, deal with input stage..

I've done all of the above and the output signal is still getting sucked up somewhere.

If I touch my audio probe to IC1-p2 it is SUPER LOUD, and then only a few components later it's back down to below the input level.

Someone recommended upping the R32 (68k) x10 to 680k. I can see the logic in it and will try that next.
Any other recommendations?

[PRR]

If I touch my audio probe to IC1-p2 it is SUPER LOUD, and then only a few components later it's back down to below the input level.

IC1 pin 2 should be near-silent (it is a virtual earth). Wrong pin? Wrong op-amp?

"only a few components later" uh, which few components?

[half_smith]

*UPDATE*
Well, after trying all of your suggestions and probing the circuit, deciphering the vague build docs, etc.
I discovered I had an incorrect resistor value, R2 was 4k7 instead of 390k! DOH!

But I learned how to boost the signal as needed by upping some of the local feedback resistors, which I've now socketed and can adjust easily.

here's the changes I made, and a VERY helpful labelled layout doc I found on the BYOC forum.

Thanks for your assistance!

[antonis]

I presume you also realized that by lowering R4, R7 & R31 values you result into same gain raise with that of raising R3, R8 & R32 values respectively..