Engineer's Thumb tone control

[Claudiog]

The Treble Boost switch is good to my intention, I put a bridge instead of switch beacuse I always use with treble on, but I found it a little bright.
Reading there, increasing 4.7n cap will let more treble, I thought that R-C filter calculate will help but is a bit confusing, if I increase cap on amz page I see less treble, so I need some help.

will be useful to put a pot instead of 10K?, reducing cap will decrease treble frequency?

[Neil mcNasty]

I might be a bit off, but this is how I read/understand the schematic:
Increasing the 10K resistor will ease off the treble boost, so replacing it with (let's say) a 25K pot should give you the possibility to dial it in perfectly.

Increasing the cap value will most likely increase the amount of lower frequencies that are being boosted (lower and lower frequencies are included as the cap value increases), and a smaller cap does the opposite and will narrow it (upwards) in frequency (you cut out more and more low and and mid frequencies as the cap value lowers, but keep the highs)

So what do I have a conclusion?
Actually I think I might

Resistor:
I think the idea about replacing the 10K resistor with a something like a 25 or 50K pot, is a good one.
So I would try that first. I suspect that this will give you exactly the control that you are looking for...

Cap:
Increasing the cap value will make the boost fatter and and lower in frequency, as the cap value increases, and it will change the frequency focus of the boost, and therefore also the pedal's "character" and "tone".

Since you also like the boost function so much (but just would like to ease it off a bit), I would not do any modifications to the cap value.
Keep the cap as it is and avoid changing the pedals character!
Add the pot and see what happens...

If you would like to experiment with the cap, then I would suggest two caps mounted on each side of a DPDT (on/off/on) Switch, and then wire the switch (leads from the two center lugs) in parallel with the 4.7nf cap.

Personally I would then try 2.2nf on one side of the switch (to make the total value: 6.9nf), and 8.2nf on the other side (total value: 12.9nf), since I have experienced that these values have had very nice musical frequencies to them, when used in other treble boost circuits.

Cheers and good luck!

Neil

[Claudiog]

thanks! I will try the pot and the cap switches then to see what I like.