Getting more oomph on Cujo fuzz

[allsmoke]

I just finished the Cujo fuzz build and really like it. If I wanted to get a little more distinction out of the treble boost switch is there any value of the board I could swap out. Doesn't seem like I'm getting a huge noticeable difference on the treble switch, whereas I'm getting a distinct bass boost from the fat switch.

Thanks all

 

[BuddytheReow]

This is a more unusual EQ, but looking at the schematic I'll take a guess saying to change the values of either r10 or r14. C6 is a maybe, but it's already pretty low

 

[allsmoke]

This is a more unusual EQ, but looking at the schematic I'll take a guess saying to change the values of either r10 or r14. C6 is a maybe, but it's already pretty low

Thank you, any suggestions on what to change to, or maybe I should socket them and try different values

 

[BuddytheReow]

@Chuck D. Bones would know better, but socket and experiment

 

[Chuck D. Bones]

The FAT and TREBLE switch do very different things because of where they are placed in the circuit. The Suhr Rufus's tone network is the familiar FMV tone stack with the TREBLE pot replaced by four resistors and a switch.

You said you want "more distinction," can you be a little more specific? More treble? Less treble? Both? Something else?

R11 & R13 determine how much treble you get with the switch in the middle.
R10 determines how much treble you get when the switch is in the Left position (assuming the board routing matches the pic of the board on the website). R10 smaller = more treble. You can even jumper R10.
R14 determines how much treble you get when the switch is in the Right position. R14 smaller = less treble. You can even jumper R14.

What I would do is put the TREBLE switch in the middle position and temporarily connect a B250K pot across R11. Pin 1 to one end of end of R11, pin 2 to the other end. Find a setting you like for Max Treble. Disconnect the pot and measure the resistance from pin 1 to 2. Replace R10 with that value (or the nearest standard value). Repeat the process with the B250K pot connected across R14. Find a setting you like for Min Treble. Disconnect the pot and measure the resistance. Replace R14 with that value.

Try that out and see if you can find settings you like. If not, then we need to get a little more aggressive. Rather than tearing up a PCB, you might consider breadboarding at least the tone stack part of the Rufus and then hooking it up to the junction of R7 & R8.

BTW, this is not a Troubleshooting question, it is a Mod question.

 

[allsmoke]

Thanks for the response. First, apologies, I guess in my head I was thinking troubleshooting because I wasn't getting much tonal difference regardless of which position the treble switch was in. It all just sounded a little the same. But it probably is more appropriate in the mods section.

As for more distinction, I'm looking for more treble boost. in the left position, I was getting a very minor boost in the left position, and nothing much in either other (center or right). I'll try socket then jumper(ing) them, or reducing the R value to see what happens.

Thank you all again, I really appreciate it.

Edited to add: HUGE difference with R10 and R14 jumpered. I may revisit R14 (since I have both socketed now).

Thank you so much again. Very much appreciated.

 

[Chuck D. Bones]

You're welcome, good to hear it's working out for you.

Why Suhr decided to make TREBLE a switch instead of a pot is beyond me.

 

[harmaes]

I’ve built the Cujo fuzz and have added a 10k in parallel to R14 to tame the fizz this circuit has.
What I do notice is that the volume roll-off on my guitars introduces gain reduction and a lot of brightness too quickly IMO. At 8 on the volume of my strat the fuzz is completely gone and the brightness is too high. Is there anything that can be modded to change that behavior to make it a more gradual reduction of fuzz? The cleanup is good but too much for me.

 

[Chuck D. Bones]

Try increasing R1. I suggest temporarily replacing R1 with an A500K pot. Adjust that until you find the sweet spot, then measure the pot and replace it with the nearest standard resistor value. My guess is you'll end up somewhere between 47K and 330K.

 

[harmaes]

Try increasing R1. I suggest temporarily replacing R1 with an A500K pot. Adjust that until you find the sweet spot, then measure the pot and replace it with the nearest standard resistor value. My guess is you'll end up somewhere between 47K and 330K.

Ok, I ended up using a 200k trimpot and installed it as a replacement for the resistor. I ended up around 150k to give the pedal a more gradual decrease of volume and fuzz. Then at 5 to 6 on the volume the neck cleans up nicely without it being too bright.