Modified B&M Fuzz

[mdc]

I heard 'Girl Like You' come on the other day and was reminded of that song's great fuzz tone in the lead part.

Legend has it, he used a B&M fuzz unit for the track. It's a Colorsound pedal, not too different from a Big Muff, in the same family as the Supa and Jumbo Tone Benders, as well as the more recent yellow hybrid. Faustone released a nice, true-to-vintage-spec clone of the original a while ago and made the schematic freely available.

I breadboarded the circuit, it sounded pretty great as-is, but the BMP tone section is pretty lossy without the final recovery stage, and has a bit more mid-scoop than I'd like. Stock, it also sounded really close to the yellow hybrid bender that I already have, so I figured I'd tweak it a little. No major changes, really, but...

• swapped the clipping diodes for red LEDs
• swapped out the tone section for a fixed -6dB cut @ ~700Hz
• imo there's no reason to have the fuzz control anything but dimed, so I left that out too
• reduced C3 (the coupling cap after the input stage, C2 in my schem below...) to 10n; that's the value on the yellow hybrid and I think it sounds a lot better with a guitar.
• reduced the miller cap on Q3 to 390pf (honestly, the only reason is because I could only find two 470s in the baggie of breadboard parts and was too lazy to go get another 470 from the other side of the room. It sounded fine, why change it?)
• added some additional filtering to the power supply section

I laid it out on vero and built it this afternoon, and it sounds pretty cool. A solid one-knob fuzz with a bit more hair than a big muff but definitely in the same family.

 

[Diynot]

Damn, I haven’t heard that song in forever! Very cool build. My favorite bass fuzz is a Stomp Under Foot Rhinosuar which is a colorsound bass/jumbo fuzz clone. Interested in the tone mod since it does lose volume. Guitarpcb has a board for it, but they add a recovery stage which then turns it into a muff. Might need to get one and try your mods out

 

[fig]

Bravo. That song always gets stuck in my head.

It looks fantastic!

Thank you so much for sharing this! I can squeeze in another breadboard and this rocks!

 

[mdc]

If you want to mess around with a different mid scoop at the end you can use the duncan TSC to fake a fixed notch:

Just set R2 to 10M (this effectively removes it from the circuit), and slide RM all the way right (max resistance).

I originally intended to just pull the tone section out completely, but I find muff-style circuits get quite muddy without a little bit of scoop. I didn't want anything nearly as dramatic as a stock BMP scoop, so I just fed the breadboard into my DAW with a neutral sounding amp sim and played with a parametric EQ until it opened up. Then I just tried to match that EQ curve in the TSC.

 

[Feral Feline]

Great IDEAS!
LEDs, Fixed-Tone, Single knob...

I'd likely put the C2 on a switch so it can be flicked between bass and guitar usage, so I'll have to breadboard that and try it. SO...

Thanks for postin' your schematic!


Oh, and I love that song. When I first heard it I thought it was from the late 60s only to find it was a current release. Lots of great tones in it, not just the lead.

PS: great that it could be EASILY built on just about any Muff PCB, too.

 

[mdc]

I built one of the yellow hybrid/marigolds for the bass player in my band with that 10n cap on a switch with a 100n and it really does make a huge difference going between bass and guitar. I thought about doing the same for this one, but since it's just for me I figured I'd keep it simple.