Adding a Tone Control

[Blooze]

Curious where would be the best spot to add a tone control into this Seamoon Fresh Fuzz circuit (ala Nash NGDP Fuzz)?




After the IC like this, or before?

 

[benny_profane]

R4 and C5 form a low-pass filter. You could change R4 to a variable resistor (with a stopper resistor in series) and bump up the value of C4 to get the frequency you want. Check out the RAT schematic to see how it's implemented there.

If you add a BMP tone control at the end like the second schematic, you'll also need to add some sort of gain recovery stage.

 

[manfesto]

If you add a BMP tone control at the end like the second schematic, you'll also need to add some sort of gain recovery stage.

Could put the BMP tone stack before U1.2 and up the gain of that stage to compensate, if necessary?

 

[benny_profane]

Sure. Also, the second schematic would work fine in terms of the order of the gain stage, tone control, and level control if the second op amp stage gain were increased. That exactly how the opamp big muff is structured.

EDIT: Is this circuit incredibly loud as-is? There's already a lot of gain here.

 

[manfesto]

EDIT: Is this circuit incredibly loud as-is? There's already a lot of gain here.

indeed, that’s why I put the “if necessary”, that second stage with the 1M in the feedback loop should more than make up for a lossy tone stage I’d think

 

[Blooze]

It's very loud. I basically just stuck a BMP tone stack in there for example's sake. I'll have to mess around with different ones, but I wan't sure where to try inserting it.

When I look at the Nash version the tone stack has two resistors and two caps it appears, IIRC.

 

[manfesto]

It's very loud. I basically just stuck a BMP tone stack in there for example's sake. I'll have to mess around with different ones, but I wan't sure where to try inserting it.

It looks like it’s basically a loud boost feeding an even louder boost, so I guess through experimentation you could decide where you prefer the EQ shaping to happen. The later in the circuit it happens the more dramatic an effect it’ll have, usually.

Do you want EQ > boost > boost (tone stack before U1.1), boost > EQ > boost (tone stack before U1.2), or boost > boost > EQ (the way you have it drawn in the original post with the tone stack last)

I doubt gain recovery will be a problem regardless of where you put it but if it is, R3 and R5 would need to be adjusted to compensate

 

[manfesto]

Actually thinking about it, I take that all back. if it’s a fuzz circuit, then all of the distortion it has is from hitting the rails of the 4558 hard, and so putting a lossy tone stage anywhere besides the end of the circuit is gonna make it hit the rails less (which may still sound totally cool and is worth testing). End of circuit makes the most sense if you wanna preserve the distortion characteristic

 

[Blooze]

This is Nash's "version". Its a stock Seamoon Fresh Fuzz (Anderton Fuzz) with the added tone control.

 

[Blooze]

I breadboarded it up once and then took a stab at designing a pcb for it. I'll have to wire it all back up and add a tone control to see how I like it if I get some time this weekend.

 

[Blooze]

Breadboarded it and putting the BMP tone control right before the volume pot works fine. There is lots of gain on hand. The values I have for the tone stack seemed to work well. I’ve tried my hand at making a pcb, but I’m gonna need guidance. I’ll start a new thread for that.

 

[Blooze]

I just cabbaged on to my previous Diptrace thread on this circuit.

https://forum.pedalpcb.com/threads/diptrace-first-try-at-pcb-layout.10204/