Op-Amp Muffs (No, Not That One)

Ginsly

Well-known member
All the hubbub around the BM2 reminded me that I've always wanted to check out an Op-Amp Muff. I used an OG Green Russian on bass for years - really good stuff, although that switch is absolutely ridiculous. I'm shocked it never popped out and blinded me on stage.

I breadboarded the Aion Corvus which is pretty faithful to the original but alters things a bit "to make the gain itself variable as opposed to running it full-up and then cutting back the level afterward". Sounds pretty excellent!

From there I tried the Pumpkin Patch mods: changed three of the six Si diodes to two green LEDs and added the AMZ presence control. You can also leave out the second trio of clipping diodes altogether for more extreme gating, but I like the middle ground of the green LEDs. Really nice touch.

Seems like there are a handful of worthwhile Op-Amp versions to try, please recommend what ya like! PCB, vero, whatever. I'd like to incorporate the gate into whichever one I build if possible. I've only looked at a couple so far:

- PPCB Dream Fuzz - looks to be 100% faithful to the original. Pretty easy to add a Diode Selector switch for gating.

- Aion Corvus - a couple value changes here and there, and the aforementioned variable gain mod - not sure how crucial that is, please chime in if you've built both kinds! Can add a Diode Selector switch for gating.

- PPCB Cleric - the Warlow sounds like one of the more aggressive Op-Amp versions I've heard, and I like that! There's a new version that has a Gate switch, although I'm not sure how they achieve that - there are no clipping diodes to mess around with in the Warlow. Any thoughts on this?

- PPCB Sour Grape - Keeley has gone from Rotten Apple>Moon>Suns, although I'm not sure how much they differ. He seemed to fix the excessive low end of the Moon in the Suns tone control, and also made the clipping asymmetrical. Don't know where the Apple fits in. Cutting one of the Sour Grape's two clipping LEDs would probably gate similarly to the Pumpkin mod (?).
 
i breadboarded both the sour grape fuzz and cleric fuzz just recently on the weekend, and compared them to my OG/V5 opamp muff build.

the sour grape fuzz was weird. it has a lot of mids in a way that makes it sound more like an odd distortion than a muff fuzz.

although people into the ‘tone bypass’ sound might have a different experience, im not into that.

the cleric fuzz was better, retains the muff fuzz character, although there wasn’t a lot going on that made me want to build it, as i still preferred the OG V5 opamp muff in comparison
 
i breadboarded both the sour grape fuzz and cleric fuzz just recently on the weekend, and compared them to my OG/V5 opamp muff build.

the sour grape fuzz was weird. it has a lot of mids in a way that makes it sound more like an odd distortion than a muff fuzz.

although people into the ‘tone bypass’ sound might have a different experience, im not into that.

the cleric fuzz was better, retains the muff fuzz character, although there wasn’t a lot going on that made me want to build it, as i still preferred the OG V5 opamp muff in comparison
Super helpful, thank you! I'm not terribly impressed with the tone bypass either. I keep the tone knob pretty high so it's a dramatic change, and not in the right direction.

Hmm sounds like there's not a good enough reason to go for the Rotten Apple or Warlow over the OG. Plus, I know the diode mod works well on that.

Have you looked at the changes Aion made? I'm not sure how big a difference they make, and if they mostly change the behavior of the Sustain pot it's kind of a moot point. I can't see running Sustain less than full-up.
 
One of the toggle switch positions on the Cleric stood out above the others. (I can't recall which though, so there's that)
Yeah I think one is a Rat's tone section maybe..?

The Keeley Psi fuzz is interesting:
Completely missed this one! How is it different than the others?

I think the cream pie fuzz is an op amp muff, and it's pretty amazing
Didn't realize that one was IC based, thanks!
 
I have yet to try it, but I've read some good things about Grind Custom's Ultra '78 (BMPOA w/ Grind's UltraStoner tone-stack).

Also

"DELUXE
https://stompunderfoot.com/blog/f/1977-1978-op-amp-big-muff™-pedals
It should be noted that another great version of the op-amp, not talked about much, is the Deluxe Big Muff.
The circuit in the Deluxe is the op-amp but it has some slight changes to it that gives it a slightly thicker sound."
 
I only built the Sour Grape and it sounds really good in a band mix, I keep the tone switch in the middle (but I'm not sure what EQ it is)
Plenty of muffy goodness but it really needs to have a REV LOG pot for the gain otherwise it will all be bunched up at the end

I am curious about the Ultra 78
 
The Keeley Psi fuzz is interesting:
ok so i finally got around to this one a couple weeks ago.
IMG_2279.jpeg
holy crap.
it’s the best opamp muff or fuzz i’ve tried yet.
i was suspicious of the npn Ge addition, but turns out it’s awesome. and a heckin loud output.

nothing i had tried previously could beat an og opamp muff, but this one does.

i’m so pumped on it, i even drew up a vero layout for 1/2W resistors and fat caps (to fit 1590BB/2)
Keeley Psi Fuzz (Opamp Muff)_1.png
 
ok so i finally got around to this one a couple weeks ago.
View attachment 112145
holy crap.
it’s the best opamp muff or fuzz i’ve tried yet.
i was suspicious of the npn Ge addition, but turns out it’s awesome. and a heckin loud output.

nothing i had tried previously could beat an og opamp muff, but this one does.

i’m so pumped on it, i even drew up a vero layout for 1/2W resistors and fat caps (to fit 1590BB/2)
View attachment 112146
Looks like I'm givin' this one a shot too! I wound up building Aion's IC Muff (minus Tone Bypass) with added Gate/Diode options and a Presence knob - changed up DBL's layout and plopped it here.

So this is better than the Warlow, huh? People seem to love that one...
 
So this is better than the Warlow, huh? People seem to love that one...
yeah idk why, massively overhyped imo.
probably because the enclosures are big and pretty, sometimes with an aesthetic very similar to the og that it’s taken circuit design cues from.
and they do look good, i love big box enclosures and i’d totally buy one if the circuit wasn’t so meh.
 
yeah idk why, massively overhyped imo.
probably because the enclosures are big and pretty, sometimes with an aesthetic very similar to the og that it’s taken circuit design cues from.
and they do look good, i love big box enclosures and i’d totally buy one if the circuit wasn’t so meh.
Good to know! I hadn’t built a Muff before that Aion/JHS mishmash I threw together, but I really, really like it. I’m really intrigued by this Psi fuzz.

For non IC versions it seems like the Kewpie is the place to start. At some point a Green Russian would be nice for bass! Years ago I used an original Sovtek for that and it did indeed sound pretty badass- even without a clean blend. When I wanted to go full Soft Machine I’d reach for the Wattson Superfuzz though!
 
Good to know! I hadn’t built a Muff before that Aion/JHS mishmash I threw together, but I really, really like it. I’m really intrigued by this Psi fuzz.
yeah if you like the og opamp muff (however modified), i'd be surprised if you didn't dig the psi fuzz.

will be curious to see how the moon / noctis fuzz compares

For non IC versions it seems like the Kewpie is the place to start.
it's certainly versatile.
if you like that, you'll probably enjoy just about any muff that has 1uF DC blocking/clipping caps (IME a lot of the distortion character is determined by these)

dig in:

At some point a Green Russian would be nice for bass! Years ago I used an original Sovtek for that and it did indeed sound pretty badass- even without a clean blend.
after trying more muffs, i'm liking this one less and less. the low end clean bleed through might be great for bass, but it's a little bit disappointing for guitar (ime).

note: the kewpie has a toggle mode that switches to 47nF DC block/clipping caps (same values as green russian) - offering an enormous bass response. and it's sick (kinda like it more than a green russian tbh)
When I wanted to go full Soft Machine I’d reach for the Wattson Superfuzz though!
tenor (2).gif
 
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