OA BMP...

[petemoore]

  turns out it's quite tunable, and with some doing the thing does neat tricks.
  Pick attacks are 'Pronounced in vowel tones, depending on where [up by the bridge or near neck] the attack is hit on single and especially double note rythms, distinct vowel sounding attack becomes present.
  I typed earlier that I got the circuit working and it sounded 'messy'...well after messyng around with all the caps, huge tones are happening for me. Good thing I used lotsa sockets!!!
  I made input and first coupling caps a bit smaller, I'm using HB pickups to test, also the rolloff caps before/during the second stage became smaller [the .0047uf ended up as .001uf], also the output caps we're changed, the bass side is .22uf and the treble side of the TC pot is .022 [or .047], very much changed from what it originally fired up sounding like [factoring in 'acclimating' to the muffyness and growing fond of it].
  One serious Muff distortion uses 2 Si diodes one way, 3 the other, and a .0022uf clipping rolloff cap...tried stock [very good, I would use that if made switchable], and numerous diode combinations [except Ge...which would probably be really good mixed in there] including LED I didn't particularaly care for.
  Tone control sounds really spectacular for me in a small portion of it's travel, glaring high mids going CW from there, Mud toward CCW...sweet spot is quite///sweet !!!
  I spent another couple hours again with the voicing, each cap [I have 8 positions socketted or easy to mod on] makes of course a difference.
  I'm not saying I've found the voicing that works right with your pickups, but voicing this thing makes for one seriously fun playing Fuzz Box !!!
  The overall bass/treble response and clipping voicing can be tuned to quite a vowel-ey, vocal sound. I have the staging caps [in series with SP, input and output cap etc.] ramping in value from input to output, trimmed the HF tone knob cap, used a larger bass cap...can't decide which voicing I like best because there are a few that work great 11
  Has a nasty IC sound !~~ LOL...[Razz on recent IC dumpost]...different than you're transistor Fuzz...certain things it does, certain other things it doesn't Great Voice!!!
  Gotta Love It !!! Takes A Bit of Getting used to, even after all the fine tunings !!

[z-zero]

Hi,

   Were you using the recent 1977 op-amp BMP schematic posted by Johan? I grabbed that as soon as I saw it. Thanks Johan! I have a 1458 and a 741 laying in my parts bin screaming to get built into an OA BMP. I've heard it sounds darker than a 4 tranny BMP and the sound clips I've heard with the ICBM from Euthmyia has lit a fire under my rear end to get it done. You don't have any way to get sound clips do you? Thanks for sharing your build with the OA BMP.

z-zero

[petemoore]

  Thanks Johan !!!
  OA BMP is heavy, I need to try getting more soundclips up again from soundclick, I'll see if I can hack my way back into 'the' [my] or 'an' account there again.
  I'ts a good thing I socketted the sh out of my BMP Board, I can strongly recommend voicing this build to taste, or count on luck to give you what you'[re looking for in it.
  Another thread contains the word "messy' in relation to the tone it made before being re-voiced, might be perfect for certain SC pickups...I'm using HB's mostly, and for testing.
  Opamp TONE [lol], the 'struggling' 741 being pushed by both halves of a Dual [I'm using 4558]..cool stuff.
  It would have been a 'mistake' to have soldered an OA BMP up, without voicing options, it almost certainly would have been dismissed as ...not so great.
  I had a good long test session, mostly jamming on it for a great while, tests real good, big fat tones, lots of stuff going on between attack and sustain//different than what I've grown used to [FF, BMP, LD, TB etc.] Very Cool Indeed to me, may not be an instantly recognized or 'preferred' flavor, at least it wasn't for me, but I quickly acquired a taste/craving for it.