Ok.. I switched the 47nf with one of the 10nf around while populating the board
Reversed them and et voila: high content present in spades.
Referencing the PedalPCB schematic (
above): are you saying you
- reduced C1 from 47nF to 10nF, and
- increased C5 from 10nF to 47nF?
I just looked at my Lollar Drive and found that I had swapped C5 for a 2n2. I definitely had found it too dark!
I too started to think my Cast Iron was maybe a bit too dark, not "open and airy" enough, and
reduced C5 from 10nF to 6.8nF (originally Tommy III value; also made a couple other tweaks).
At first I thought this change made it perfect, but now I feel it might be a bit too bright, at least with a bright guitar. (I'm kind of thinking 8n2 might be the Goldilocks value, but I'm hesitant to change C5 again, as I semi-damaged the through-hole plating when removing the 10nF.)
However, what's really bothering me now is that turning the treble down lower than 10:00ish or so also starts to radically cut the volume. I'll have to pull out my Tommy III build to compare, but I don't recall the treble control having such a drastic effect on the overall volume. But obviously that mids circuit makes the Cast Iron deviate significantly from the Tommy.
Just thinking out loud - is it possible that mids circuit is loading the previous stage too much? When the treble pot is at the lower part of its sweep (i.e. highest resistance), that combined with the mids circuit is maybe just too much?
I wonder if it would make more sense to put that last op-amp stage (i.e. the buffer) just before the mids circuit? Not sure if it's comparable, but the
Crunch Captain Deluxe (CCD) has a presence control that is similar to the Cast Iron's treble control. The CCD also has an active mids control after the presence control, but there is a buffer (BC549C) between.
My other thought on improving the Cast Iron's treble control: perhaps the treble pot could be changed to linear, and used to sweep between two different capacitor values?
