Deciding where to boost volume

[mark2]

So I have this schematic, the bulk of which is the FV-1 "Typical Application" circuit with enhancements from PedalPCB (via the Arachnid board and similar). 

In other pedals it's been able to provide above-unity, but for some reason (yet TBD) I'm getting volume drops this time.

To boost the volume, what makes the most sense?
* Increasing R34 and R32 going into the volume (inverting opamp U6.2) ?
* Increasing the volume pot value?
* Modifying U6.4 for a boost?  I presume this is just an output buffer with some frequency shaving?

Something else? Thanks in advance.

[Keppy]

R32/34 would have to be decreased, not increased. That's probably not the way to go.

Bumping up the volume pot is simple. So is increasing R36. Capacitors C17/18 are limiting the bandwidth in those sections, so make sure that whichever resistance you increase, you decrease the cap by the same factor.

You're also losing volume due to the voltage divider made by R31/33 and the mix pot. My preferred mix control would connect the outside pot lugs directly to C15/16, pot wiper to the opamp through a 15k resistor, and eliminate the other three 15k resistors in that section to prevent the extra divider path to Vref. If you don't want to do that though, I say just bump up the volume pot or R36.

[mark2]

My preferred mix control would connect the outside pot lugs directly to C15/16, pot wiper to the opamp through a 15k resistor, and eliminate the other three 15k resistors in that section to prevent the extra divider path to Vref.

Thanks for the info and thoughts. Definitely very helpful.

When you say "other three 15k resistors" are you also referring to R35 between those last two stages?

i.e. like the following

[mark2]

By the way, while trying out a higher volume pot I discovered why this pedal is quieter than others I've built with the same general layout...

I flipped the "Mix" and "Vol" pots, so Volume was only 10k.

[Keppy]

That makes sense. You'd lose 20dB at max volume with 10k instead of 100k.

When you say "other three 15k resistors" are you also referring to R35 between those last two stages?

i.e. like the following

No, R35 must remain in place. It sets the gain for U1.4 along with R36.

I was referring to R31-34. Your new schematic has R32 but not the other three, which is exactly what I meant.