Big Muff Pi Mod Ideas

[Guitarfreak]

As you probably know from my other thread I am starting to line up a set of mods for my pedal and I have a few questions.  Do you think that there is a way to clean up the low end of the gain sweep AND dirty up the high end?  i.e. gain at 0 is more or less a clean boost retaining only the color of the circuit and gain at 10 is over the top dirt and breakup.  Theoretically possible or no?

[petemoore]

Do you think that there is a way to clean up the low end of the gain sweep AND dirty up the high end? I don't know that there isn't one.
  I do know that the low end can be reduced, easily at the input wire, simply splice-insert another cap there. Also at points beyond in the signal path, but the inter-stage caps are a bit harder to get to. All in one place early, or shaving off touches later on in the circuit...
  And dirty up the high end.
  Things you can try:
  Dirty everything up and reduce everything except the high end.
  Another way might be to attenuate a little bit, everything except the 'brilliant' content [a 470k 470pf put in the signal path], early on but somewhere after Q1. 
  i.e. gain at 0 is more or less a clean boost retaining only the color of the circuit and gain at 10 is over the top dirt and breakup.
  Theoretically possible or no?
  Er...here's the theory of the BMP asIunderstand it.
  It makes lots of gain, much of it shunted to ground because the diodes cut down a good portion of the wave, twice.
  Input>Transistor gain stage [maybe a touch of dirt right here, signal tap or build this stage, try comparing an LBP to the BMP, at least the first stage of the BMP to the LPB.
  Q1's boost is then attenuated by the sustain knob [basic volume knob, but between Q1/Q2].
  Entering Q2's boost/clip/voicing stage as a larger AC potential, trying to be boosted even much farther but running into the C/B feedback diodes hitting the 'ceiling' = distortion and compression.
  This fairly dirty output hit's Q3 and a repeat of Q2 further compresses and distorts.
  Tone knob, then a gain recovery stage [compare to Q1 for fun] after the tone control's passive filtering losses.
  Allowing pre-attenuated signal through a turned very low sustain knob into Q2 tends to produce a distorted and compressed signal into the TC>Q4>output.
  In the absence of pages of options, which are available to readers here, bypassing Q2 or Q3 would reduce the compression feeding Q3, this 'always kinda hot' signal.
A lift the diode clipping threshold[s, try assymetric.
B lift some diodes
C those are LP filtercaps across the diodes
D interstage caps are HP filters
  You can mess with the:
1 Tone control[s super info-active TC download: Duncans Tonestack Calculator [freq. out mahn, knobs and graphs, no splainin' necessary except dreams come true with it].
2 Emitter resistors: bigger = less gain.
  Ime, in decending numbrage of mileage.
  BMP does really nice sustain-distortion tone. Tends to take any signal [even dinky] and ''sustain'' [compress] and ''distort'' it [twice clipped pre-boosted signal] very effectively. Clipping = compressing, nothing over - signal level gets past the diodes [depending on their threshold]. Do that twice and basically the dynamics are squashed flat-ish, and just about any small signal will hit the diode threshold.
  Find what trips the sound you'd like to find for the 'other vibe' using the BMP stages [audio probe style or just build the fragments], or anything else.
  Breadboard...bypassing a transistor as I suggested will change the tone, Dist amount, volume.

     
 
 

[Guitarfreak]

Alrighty, so I just got struck with the inspiration to get off my ass and do something (don't you hate that?) and I have an idea about how to accomplish what I want to do.  BTW Pete, I tried searching for the tonestack calculator but they don't have one for Mac, so I am out of luck DOH!  Any Mac-friendly programs that I should look into?

Going along with my idea of widening the gain sweep (at gain = 0 the pedal works much like a clean boost except it still carries the tone of the circuit, I want a good amount of headroom here if possible.  And at gain = 10 I want a ridiculous amount of gain)  The Big Muff has a few clipping diodes in it for cascading the gain structure of the unit.  I think that if I replace the diodes in the input section of the unit (the ones associated with the gain/sustain knob) with diodes that clip a LOT, and either replace the ones everywhere else with either soft clipping diodes or bridging them (with a strip of thin metal) that it would achieve what I hope.  Right?  I hope it's right haha.

Next question.  I am also going to do the Creamy Dreamer mod to it simultaneously.  I read on a website that all you have to do is replace ALL the resistors with 15kOhm resistors... and that sounds a bit off to me.  Like it doesn't sound very methodical.  Does anybody know anything about it?