True bypass problem

[LucaCripap]

Hi all, I'm Luca, a DIY guitar pedal maker. I built a quite good delay pedal, but I noticed this weird stuff: when the pedal is in bypass mode, the volume lowers. Is it normal?

Thank you

[induction]

It's probably easy to fix, but we need more information:

Which circuit? (A link to a schematic would be best.)
What layout?
How much does the volume change in bypass?

If it's true bypass, then it's possible that the problem is that a little bit of boost is built into the circuit. This is not uncommon in delay pedals that are built with true bypass but designed for active bypass. If the circuit is never completely bypassed, then unity gain is not crucial.

Anyway, it should be easy enough to solve if you can answer the above questions.

[LucaCripap]

This is the PCB with the components: https://app.box.com/s/5l3uvedjevn71jyv4epo0mybl3jjhwqo

Thank you for your help! It is based on rebote delay 2.5, basically the same but with some modifications and a loop controller.

Cheers
Luca

[induction]

Nice layout. I can't tell how the circuit works from it, though. I need a real schematic.

The dry amplitude on the stock rebote 2.5 can be reduced by increasing the 24k resistor that's between pins 2 and 7 of the op-amp in the linked schematic. I don't know what mods you made to the circuit, but that might be a place to experiment. Try 33k to start.

That said, I've never heard complaints about unwanted boost from the rebote 2.5, so it's possible that it was caused by your mods, whatever they are. In that case, I can't be much more help without seeing a schematic.