How to set EQ on pedal design?

[falco_femoralis]

Hi all, I built a Sandspur, which I love for its warm yet bright, saturated tone. Many pedals sound dark to me, especially with reverb, but this is great. I also built a Fuzz Aldrin and this suffers from the same kind of dark tone many overdrives do, unless I max the brite control and both the range and fuzz. But it has less noise than the Sandspur. So I breadboarded a circuit using the Fuzz Aldrin's input stage and in place of the second part, which is a variation of a Fuzz Face, I built the Sandspur circuit. I omitted the fuzz and brite controls. And it sounds like a Sandspur, nice bright, warm, and saturated, but the low freq control is nice - just a bit of oomph. None of the boomy low end that some of my other pedals tend to have. So that got me wondering - what are the parts of the circuit that determine the EQ?

I'd like to get back to the breadboard and experiment with this circuit, but it can be overwhelming so I'm wondering where should I start?

 

[JohnnyCreepy]

Short answer:
-series coupling cap sizing
-bright cap across volume pot (220-470pF)
-emitter resistor bypass cap sizing (smaller values give brighter sound)
-tone controls cap and resistor values

 

[Paul.Ruby]

All of these caps are dragging down top end, so play with these.

 

[falco_femoralis]

^ Thank you. I breadboarded the Fuzz Aldrin last night and that's what I discovered, the caps going to ground affect the highs. and mid highs. I tried a few different value caps but my favorite sound was with the Brite control and C13 and 14 removed entirely, and the Q's swapped for BC108's. In the end the sound was too similar to the Sandspur, so I left it alone for now.

 

[Alan W]

. In the end the sound was too similar to the Sandspur, so I left it alone for now.

I really fall into this trap: I like a specific tone signature, and if I’m not careful, modify many pedals to this signature; then, I wonder why they all sound so similar!