Big Muff Pi mods

First off, excuse my ignorance...

I'm relatively new to effects in general. I was always a guitar straight into amp kinda guy, but in my home studio I've been needing FX's for various projects/tracks.

I'd love to build a Muff clone, but there are a few variations and some room for mods/tweaks in the circuit.

Help out an FX noob and tell me which Big Muff schematic version is your favorite and what mods you'd recommend.

Well, here (http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=108&Itemid=26) is a pretty all inclusive set of schematics and such for the DIY Muff builder.

That said, I'll give my thoughts about what I like about the different ones:

- triangle muffs (first few years of production) - I was lucky enough to have a first year Muff. I really liked how it sounded a bit softer than other ones, and had the most phasey sorta thing on note decay. While most folks want to attribute it to the transistors, IMO it was because the 2nd & 3rd gain stages were driven much gentler in their feedback loops.

- ram's head muffs (my favorite) - this is the Muff that Gilmour has used for years. It is much more aggressive than a triangle. The 2nd and 3rd gain stages are driven harder, and the input cap is much bigger. I also like this tone stack the best. I also like the Pete Cornish type mods for this pedal, which mainly comprise altering the tone stack to push a ton of mids, and decreasing the coupling cap to the final gain stage so that it only passes mainly midrange. Think of the solo on Comfortably Numb, and there you are.

- early green Russian Sovtek muff - low gain transistors make for a much darker and rounder Muff tone. The greenies used military surplus ones with no legible markings, unfortunately. I've found BC237B's to be pretty close. But if the gain is too low, the fuzz will be extremely mild.

General mods that I like:

- Some folks pull the first pair of clipping diodes for bass usage. It's a little extreme, IMO. I like to replace them with LED's. It's a good compromise, IMO.

- I like mixing up transistors. The BC239C is the classic ram's head tranny, but a 2N5088 works just about as well (lotsa gain). The aforementioned BC237B's are great for softening things. I also use BC550C's to cut some noise down as well, sometimes. Sometimes I put the higher gain trannies in the slots with the diodes, other times I use them for push/boost and recovery, in slots 1 and 4.

I hate the whole mojo component thing, but really do prefer a Muff with ceramic coupling caps (all of those .1uF caps). I use monolythic multilayers, and get great results. I use electro's in the FB loops tied to the diodes - big 1uF caps for both clipping stages (some folks stagger them). I like a 1uF input cap (small film cap works great for this), and the 39K input resistor that the ram's head uses - it balances well and kills most RF interference. I also tend to bump up the output cap to .45uF.

When you look at the different schemos, the tranny stages should look like AX7 gain stages after a little bit.

This is very cool. As I mentioned in the "what should Johnny build" thread, I've just gotten myself into this stuff as well. I had planned to build a fuzz of some sort, as (again, like Johnny) it's a flavor that I just don't have in my arsenal - and because they are generally not the most demanding of builds.

At this point, it sounds like I'd be smart to go with a muff design, and house it in a bigger box to leave room for experimentation.

I have the New York reissue (the one that came in a wooden box) - and I really underwhelmed by the sound of it. I remember enjoying some old Big Muff's which I have played with in the past, I really must get round to trying to convert my NY muff to a Rams head or something sometime.

I really must get round to trying to convert my NY muff to a Rams head or something sometime.

You might want to try swapping out the 4 clipping diodes for plain old 1N4148's instead of the Schottky's that are in the NY RI. They have a slightly higher forward switching voltage than regular silicon diodes, which changes the sound just enough (you lose some compression).

...That could possibly be all that you'd need to do!

This is very cool. As I mentioned in the "what should Johnny build" thread, I've just gotten myself into this stuff as well. I had planned to build a fuzz of some sort, as (again, like Johnny) it's a flavor that I just don't have in my arsenal - and because they are generally not the most demanding of builds.

At this point, it sounds like I'd be smart to go with a muff design, and house it in a bigger box to leave room for experimentation.



Yeah, I'm not even a fan of fuzzes. Then I started thinking about some of those old Smasshing Pumpkins tones and other stuff in the '90s... I could totally use that type of sound - so here I am, planning on tracks with a cranked amp with a Muff in front :)

I'm wondering if a Fuzz Face would be a better choice (I've already dropped the idea for a Gibson Maestro clone).

On a related note, I never thought I'd use a Rangemaster much, but a buddy came over today and I put the RM in front of a Vox AC15/30 build and a plexi build - he was ecstatic, I was listening and realizing how great it sounds. It looks like I'll be building a RM clone for him and a Muff for Bass for his friend.

You might want to try swapping out the 4 clipping diodes for plain old 1N4148's instead of the Schottky's that are in the NY RI. They have a slightly higher forward switching voltage than regular silicon diodes, which changes the sound just enough (you lose some compression).

...That could possibly be all that you'd need to do!

Thanks! I was just comparing the circuits, and almost every resistor and cap is a little different, which looked daunting. I will try the diodes.

Are 75V 150mA diodes OK for this?

Thanks! I was just comparing the circuits, and almost every resistor and cap is a little different, which looked daunting. I will try the diodes.

Are 75V 150mA diodes OK for this?

Any diode that switches on with between .550 mV to .650 mV is fine, IMO. Just hook your multimeter up and see what kinda numbers you get.

As far as cap and resistor differences, I really think that there are only a few key ones, but that's just my take. I consider them to be the following:

- input cap and resistor s/b 39K and 1uF for a ram's head

- the series cap with the diodes in the feedback loops is the key to the spectrum of clipping frequencies. If it's too muddy, make the caps smaller. If it's too thin, make them bigger. I like 1uF for both, but lots folks will cut the first clipping stage down to a .047uF or .1uF cap

- the resistors from the emitters to ground can also affect things, but typically moreso when you get closer to 1K or higher (I guess that 820 ohm is also close enough). Folks obsess over whether they s/b 100, 150, or 390 ohms, but I find the variations to be tiny (if any)

- the tone stack values are critical, IMO. The bass resistor/cap combo s/b 39K/.01uF, period. If you want more bass, increase one or the other, but those two values are very standard for the oldest Muffs. The treble cap/resistor combo is important, too. For max scoop, it s/b .0039uF/22K. For a little less scoop, subbing in a 39K like some triangles had is nice. Many people replace the treble resistor with a 25K (trim)pot and the cap with a .022uF, so that they can dial in more mids. And at extreme settings, you can approximate the stock HP filtering (pot set to ~3.9K).

I believe that the NY RI only uses a 22K bass resistor - that's too small, IMO.

Here's a good page (http://rkerkhof.ruhosting.nl/Taas/Mods/Big%20Muff.htm) for a bunch of info on different Muffs, as well. He can go a little overboard at times, but overall a decent site/page.

If you like Pumpkins tones, I vote for a Skreddy Mayo clone. It's a triangle Muff with some minor (but tasty) mods. I can play about anything with the pedal on and it's guaranteed to induce a dumb, blissful grin. It does that for me at least.

thanks for the low down, 11 Gauge. I shall try the diodes first and then progress if that doesn't give me enough of what I want.

I vote for a Skreddy Mayo clone. It's a triangle Muff with some minor (but tasty) mods.

For me, the best modded Muff clone that I've yet to hear is probably the Dice Works Muff Diver (or Epic when paired with a MkII). While I hate toggles for the most part, the ones on the Dice Works are incredible, especially the unofficial "Cornish modes."

The most amazing thing about the Dice Works is that it uses ordinary "greenie" caps throughout, and it still sounds absolutely fantastic.

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Some of the oldest Muffs only used ceramics and while I've never played one of those models, I've never heard or read a bad thing about them

Any diode that switches on with between .550 mV to .650 mV is fine, IMO. Just hook your multimeter up and see what kinda numbers you get.

As far as cap and resistor differences, I really think that there are only a few key ones, but that's just my take. I consider them to be the following:

- input cap and resistor s/b 39K and 1uF for a ram's head

- the series cap with the diodes in the feedback loops is the key to the spectrum of clipping frequencies. If it's too muddy, make the caps smaller. If it's too thin, make them bigger. I like 1uF for both, but lots folks will cut the first clipping stage down to a .047uF or .1uF cap

- the resistors from the emitters to ground can also affect things, but typically moreso when you get closer to 1K or higher (I guess that 820 ohm is also close enough). Folks obsess over whether they s/b 100, 150, or 390 ohms, but I find the variations to be tiny (if any)

- the tone stack values are critical, IMO. The bass resistor/cap combo s/b 39K/.01uF, period. If you want more bass, increase one or the other, but those two values are very standard for the oldest Muffs. The treble cap/resistor combo is important, too. For max scoop, it s/b .0039uF/22K. For a little less scoop, subbing in a 39K like some triangles had is nice. Many people replace the treble resistor with a 25K (trim)pot and the cap with a .022uF, so that they can dial in more mids. And at extreme settings, you can approximate the stock HP filtering (pot set to ~3.9K).

I believe that the NY RI only uses a 22K bass resistor - that's too small, IMO.

Here's a good page (http://rkerkhof.ruhosting.nl/Taas/Mods/Big%20Muff.htm) for a bunch of info on different Muffs, as well. He can go a little overboard at times, but overall a decent site/page.

Thankyou so much for your advice! I changed the diodes and the tone stack resistor as you recommended and a pedal which for 8 years has been unusable to me suddenly sounds great and just how I wanted!

I changed the diodes and the tone stack resistor as you recommended and a pedal which for 8 years has been unusable to me suddenly sounds great and just how I wanted!

Isn't it amazing that there are a few critical parts in the Muff circuit that define it's sound, for the most part? The rest of the circuit is very forgiving and generic (to a point).

Lotsa folks get hung up on the transistors. While they are fun to tweak, you aren't going to get a lot of variation (IMO) unless you're going to a significantly different gain range.

IDK why EH went with the Schottky diodes over regular 1N4148's for the NY RI. Very odd choice, IMO.