Weird tone control or not?

[Ben Lyman]

While experimenting I stumbled on this combo for a tone control on my Bus Driver OD pedal, which is just a modified Electra. But I really like the way it works and I was just wondering if it is a weird way to do it or if this is something that is used often for tone on a distortion pedal. Is there anything that could be bad about this or is there another way to acheive the same results? Also, I thought this would make the level control have some affect on the tone but it doesn't seem to.

[Phoenix]

As you turn the tone control down, it'll make a voltage divider with the volume pot, and with those values, you'll lose half your signal with the tone control at 0. You could increase the value of C7 and decrease the value of the tone pot to minimize this effect. But if you still like how it works, does it really matter?

[nocentelli]

The 100k pot followed by the 1n to ground is the same type of filter arrangement used in the Rat (which uses a 3n3 cap for a lower LPF frequency, i.e. rolls off more treble in a wider band, down to a lower frequency). The 1n cap across the volume pot is sometimes referred to as a treble bleed cap, and preserves high frequencies when the voltage divider level pot is dialled low: It is more often found on the sustain control on modern clones or variations of the BMP. I would imagine the filter pot is fairly subtle, and somewhat negated by the treble bleed cap, however YMMV since the effect these filters will have is somewhat dependent on the stage that precedes them.

[Ben Lyman]

You could increase the value of C7 and decrease the value of the tone pot

I like this idea, thanks. As for losing volume, Yeah I was aware but I accounted for it when I made the pedal. It's got a ton of boost even with the gain off. My test is to turn gain off, tone down, level up and compare volume level of bypassed to effect on... still boosts so that's good enough for me, it's a very muddy lo-fi setting that probably nobody would use but it's just a test. I am going to try that idea of yours on my next one with a smaller value pot and larger cap.

The 100k pot followed by the 1n to ground is the same type of filter arrangement used in the Rat... The 1n cap across the volume pot is sometimes referred to as a treble bleed cap...I would imagine the filter pot is fairly subtle, and somewhat negated by the treble bleed cap, however YMMV since the effect these filters will have is somewhat dependent on the stage that precedes them.

Yes, the Rat is where I got the idea, but I don't like the way the standard Rat values affect my output tone so I went more subtle on the filter. I tried a lower output value cap and I didn't like the sound I got, maybe less distortion and sustain or something. Anyway, I really like the 1n filter, it gives what I call a "realistic range of usability" 
However, as soon as I add that 1n, the highs get slightly cut so I was trying to figure out a way to bring them back, and yes, you are right it's a treble bleed, I hadn't even noticed that! I used to add TB's to my guitars and even experimented with them on a fuzz face I made.
As for subtle? No, not really, I call it my "subtle tone control" sometimes but it's actually very effective. Plenty of filter for the high gain stuff when you don't want ice pick tone, and now with the addition of the treble bleed I get plenty of highs for low gain volume boost without turning to mud.
And another bonus is that it's only two caps and a pot!
Thanks guys, I appreciate your input and you really helped me to understand it more betterly.

[anotherjim]

Assume source impedance is low (10k-ish or less) with R10 max, then at frequencies low enough that C7 isn't passing anything, increasing R8 reduces amplitude out up to -6db (half) when it's max. C7 starts to cut treble significantly from 1.5Khz while R8 is 100k. With R8 + source worth 30k it is cutting about 5kHz - the top end of a guitar cab.
Fuzz filters can start as low as 300-500Hz - since it is only a single pole filter - not all that steep - starting lower than you might think can make the simple RC filter seem more effective. So C7 can probably be larger. Depending on source impedance, 2n2 or 3n3 might be good.

A more usual way is to have the wiper of R8 only connecting to C7. Then changing R8 does not change the out level, just the R of the RC low-pass formed with C7  - it would always be down by half with R8 & R10 equal.

[Ben Lyman]

Cool, thanks Jim, I'm learning more and more by the minute.  I will try the cap to wiper thing and a larger C7 on my next one, especially if I have to make one for any of my friends. For now, this one is just for me and it's boxed up so I am simply going to tack that 1n onto the level pot and call it good.