Big Muff mod I want to try, will it work and how will it sound?

[kylecavanaugh]

Here's an original schematic of a Big Muff.  What I want to try is to make a Muff with 4 gain stages and 2 clipping sections with 2 gain controls (possibly ganged pots?) and be able to mod a stock Muff instead of having to build it from scratch.  SO, here's what I drew up (more like cut and pasted)



As you can see, I bypass the tone stack and used the last gain stage (which will be slightly different than the mod schematic) as a clipping stage and use the 3rd gain stage as a buffer instead of as a clipping stage.  I did something like this before with great results but not quite in the same fashion, it sounded like a high gain tube amp, very good for Heavy Metal, of course that pedal crapped out on me after fiddling with it too much (ugh)

As for the tone stack I don't think it'd be a good idea to use it late in the circuit because of the volume losses it causes, but I was thinking of using a presence control (pot and capacitor) so there's at least some control over the tone.

Any thoughts?

[Ben N]

I'm a bit confused. You don't really describe what you are after tone-wise.

Also, by nomenclature. A stock transistor BMP has four gain stages: The input/drive stage, two clipping stages, and the recovery stage after the tone stack. You describe your modded third stage as a "buffer", but that isn't what the schematic shows--it shows a high gain booster, identical to the input stage. Given that the signal has by this point already been boosted to here and gone, that will still be a clipping stage, just transistor saturation clipping instead of diode feedback clipping. If that interests you, you might want to have a gander at the Whisker Biscuit at runoffgroove.com. You might also want to take a look at Joe Davisson's various Obsidian permutations. 

You might also want to search out Mark Hammer's discussions about filtering in multiple gain stages.

In any event, I doubt you could do this as a mod of a BMP board, or would want to. What you have basically is the front half of a BMP x2, rather than a BMP mod.

Anyway, it looks interesting. Try it and let us know.

[MikeH]

I don't know how it will sound, but it looks like you'll need some sort of dc blocking cap on the output.  1uf?

[Ben N]

I don't know how it will sound, but it looks like you'll need some sort of dc blocking cap on the output.  1uf?

Indeed.