Op-amp Big Muff Mod: Noise Gate

[lars]

Disclaimer:  Please don't try this mod on an actual vintage Op-amp Big Muff!

This is a mod I stumbled upon while breadboarding and has nothing to do with me understanding whats going on with the circuit. To get a noise gate effect, lift the 820k resistor connection to pin 3 on the 741 op amp.
This does reduce the overall gain and sustain of the circuit, but also makes the pedal dead quiet while not playing. It works especially well for bass guitar and gives a very "ripped, torn, zippery" sound to the notes, it's fun to play! On guitar, higher notes take on an almost 8-bit quality, and the decay is similar to an EHX Microsynth, very sputtery and grainy. The effect is dependent on how hard you hit the strings. Hit them hard and you get the typical Big Muff sound. Lighter playing results in a low-fi "bit-crushed" sound. It really makes for a unique fuzz tone.
I recommend using a switch so you can turn the effect on and off.

[Scruffie]

You're just mis-biasing the output OpAmp by removing its voltage reference... not sure how good for it that is.

[Govmnt_Lacky]

"ripped, torn

The Rip Torn effect



GET BACK TO BUILDING PEDALS.... MY BOY!!!

[lars]

Funny picture, that accurately portrays what this sounds like. It really is a great effect IMO, and my Big Muff clone hasn't blown up in over two years with this mod on it, so it's not hurting anything. I guess I should get a sound clip up, otherwise it just sounds like a good way to ruin a Big Muff.

[Scruffie]

Thinking about it, it's still grounded via the 1M in the divider so yeah it's probably fine...

I'm guessing it sounds like heavily driven mis-biasing and I must admit, sometimes that can sound fun.