Reducing bass in DIY tube stompbox

[emu!]

a few years ago, I built this:

http://www.dogstar.dantimax.dk/tubestuf/mchowit.htm

It seems to be a little dark. If I want to brighten it up, would I just change the 100uF cathode caps to 25uF???

I also want to add a passive tone control, kinda like on a guitar...one outside lug sent to ground to "roll off" some treble after the above change is accomplished. Where is the best place to insert this tone control into the circuit? I am guessing at the very end, right before the output jack.

Thanks,

[11 Gauge]

It will still be dark with the 25uF caps, especially because the cathode resistors are big. I would personally drop down to 1uF, and adjust from there.

You can put your treble bleeder after either C6 or C8. But don't put it after R8.

You could also put different cathode bypass cap options on toggles or rotaries. With the right values, the tone circuit probably wouldn't be necessary, and the effect should potentially sound better. I.E. you aren't boosting too much highs only to try and passively remove them down the line.