Mystery Machine Gain Volume Issue

[jeffhess74]

I love building pedals and I'm learning a lot as I go. But I have a knowledge deficit when it comes to schematics. Lol

I recently built the Mystery Machine, everything works and I like it a lot. The only thing that I wish I could change is the volume difference between the clean and the Distortion. From what I've read this is normal for the circuit but it would be a more useable pedal if the volume difference wasn't so extreme.

With that said, does anyone know a way to lower the output volume of the Distortion side? With my minimal schematic knowledge my first guess is to change the value of R11, thinking that increasing that resistor value will lower the signal level. Is this even close?

Any help appreciated.
Here's the schematic:

https://docs.pedalpcb.com/project/MysteryMachine-PedalPCB.pdf

And, I have attached a pic of the finished pedal if you're interested seeing it.

 

[Feral Feline]

I wonder if increasing the GAIN pot from C5k to C10k or even C20k might help.

 

[jeffhess74]

I wonder if increasing the GAIN pot from C5k to C10k or even C20k might

I wonder if increasing the GAIN pot from C5k to C10k or even C20k might help.

I don't know. But I don't want to try to remove the pots in fear of damaging the PCB. I did try lowering the value of R6, the resistor between the C2 collector and the rail, which did lower the volume of the gain stage. But, it also seemed to increase the dry signal too much. So, still researching a solution.

 

[Brett]

Try this:


The way this works is that when distortion is activated, you'll also be switching in an a secondary volume control. Start with distortion off and distortion trim set to minimum. Set volume of the pedal with distortion off. Activate distortion, adjust the distortion trim until you reach the desired volume. Then, when you switch distortion on, it activates the secondary volume control to pad the output with the distortion trim's setting.

 

[jeffhess74]

Try this:
View attachment 72232

The way this works is that when distortion is activated, you'll also be switching in an a secondary volume control. Start with distortion off and distortion trim set to minimum. Set volume of the pedal with distortion off. Activate distortion, adjust the distortion trim until you reach the desired volume. Then, when you switch distortion on, it activates the secondary volume control to pad the output with the distortion trim's setting.

That's a great approach and I appreciate the help. Is there a way to use this same basic approach but only using a resistor instead of a potentiometer?
Thanks again.

 

[Brett]

The approach would have to be adjusted, but it is possible. You'd lose the ability to adjust/fine tune the volume discrepancy though if you ever wanted to change it. Why not use a trimmer instead of a full size potentiometer?

 

[jeffhess74]

My main thing is not having to drill another hole messing up the finish and layout. I guess using a trimmer I could keep the adjustment feature while storing it inside the pedal.

 

[jeffhess74]

Hey, Brett.
That worked. I did end up installing the pot on the front just below the gain. I don't mind it. Thanks for your help. You da man!!

 

[Feral Feline]

Looks great.

That's the way I'd go, have the two volumes both accessible as opposed to a trimmer inside.