I built the runoffgroove big daddy (gain stage) using all specified parts. Problem is, it sounds like my tone knob is rolled all the way down when I turn the unit on. Volume boosts, and the distortion is there, (not sure if it is the right distortion sound, mind you, i never built it before) but it sounds dull and muddy. Any ideas?
Really? What would halving the value do? Is it suposed to sound that dull?
Halving the value would decrease the amount of treble loss, but not entirely exterminate it. The capacitor in conjunction with all the things offering resistance behind it form a low-pass filter, in which all of the frequencies over a certain level (the "highs") get bled to ground.
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^In theory, yes.

However, I tried this with 2u2, 1u, .047u, and .022u, and .01u and didn't hear any difference at all.

I just left it out completely. The only drawback is a tiny ammount of hiss that gets through, but that'll prolly go away when housed in a metal case.
I understand how a high pass filter works, but I don't think it should sound so muddy. I listen to the clip at runoffgroove, I think I am doning somthing wrong.
I'll try it tomorrow.

What I don't get though is this


Sounds way different than mine. I have way less treble, way less attack, and not a lot of transpericy either. Less gain as well. As if you were listening to that clip wearing earmuffs underwater.
Sorry but your all wrong...

The purpose of that 2.2mF cap is to increase the gain of that particular stage. It creates a path for the signal to pass through easier than passing through the resistor. Bypass cap values are usually 0.68mF, 25mF, 50mF, 330mF. Though there is not a whole lot of change in tone between them all. All that being said your actual guitar signal never passes through the cap.

So to those who tried to talk about filters, nah...

Something is definitely wrong though cause looking at the schem this circuit should be clear not muddy. I think there is an error on your end, go back and triple check your build. If all that fails play with the coupling caps (0.0068mF, 0.1mF).

Check that first resistor 4M7...say if you accidentally put a 4K7 there your input impedence would be wonko and that would explain the dead sound.
Yeah, i figured i messed up somwhere. I did use the 4M though, first thing I did was check all values.
Not sure if it would make much difference but isn't that first resistor supposed to be 4M7?

Not sure if that 700K would make much of a difference, just throwing it out there...