Multi Muff - Project Thread

[daryl]

MULTI MUFF

I'm not treading any new ground with this project.

I simply want to look at different versions of the BIG MUFF pedal, see what the main differences are and build a single pedal that is adjustable to sound a bit like like each of them.

I decided that it would be impossible to recreate them all exactly in one pedal, so what I chose to do was find the 3 things that made the biggest difference to the sound of the pedal and make those parts adjustable by adding 3 rotary knobs.

Using the Violet Rams Head as a base as I like the sound of it.
Schematic:http://www.generalguitargadgets.com/pdf/ggg_bmp_vram_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a


Step 1: What areas make the biggest difference between the big muff variations

For this I looked at the information on GGG website and the schematics they have for the different versions and came up with this:



http://www.generalguitargadgets.com/projects/17-distortion/108-big-muff-pi

Obviously its not exhaustive, as there were lots of different values used within any one of the versions.

But I believe that GGG simply went for the most commonly found when they came up with their schematics for the different versions.

This spreadsheet made it clear to see where the differences are, but I still needed to know which areas made the most difference to sound.

For this I looked at any article I could find on the BIG MUFF, there is lots of contradictory info so I went for what seemed the most credible and generally accepted view.

There were two articles in particular from people who were trying to find out the same thing:

I just spent the  whole weekend tinkering around with a Big Muff on a breadboard. My goal: to find out what the real difference is between all of this different versions floating around.

This was my first time with the Muff circuit. When I first decided to built it, I experience what most first time muff builders probably experience: The feeling of being completely overwhelmed with all of the different schematics! I found lots of information about mods and how the circuit works, but very little definitive info on what really makes a Green Russian a Green Russian, or a Triangle a Triangle, etc. This is not surprising, since there can be half a dozen part differences even within the same version. So, what does it all mean? That's what I was determined to find out.

I collected every single schematic of the transistor Big Muff Pi I could find and then set about swapping out every single component that differed between versions, putting them on switches and carefully flipping back and forth between them listening for subtle tonal changes. Where it seemed necessary (when components interacted), I sometimes put two of three components on one switch, so that I could hear the differences between swapping out all of them at once. After hours and hours of testing, this is what I found...

-------

Most of the parts changes between different versions make little to no difference in the sound of the pedal. The differences in most of these parts just lead to very small changes in gain. They did not really effect the overall tonal quality of the pedal. Any difference in sound was very subtle for most values, so unless you are trying to build a perfect replica of a 1974 Rams Head blah blah blah... it really doesn't matter. If you are more interested in just tuning in a great sounding Muff, then you can forget about 75% of the stuff that differs between schematics. It really does not make enough of a difference to worry about.

The transistors don't really matter whole lot either. I didn't have a lot to choose from, but the ones I did test sounded only very subtly different. And I really do mean "subtle." I can hear the difference between a JRC4558 and a TL072 op-amp like night and day. This was not nearly as big of a difference as that. Unless someone can recommend a transistor I should try that really makes a difference, I'd be just as happy with standard 2n5088s as anything else in a Muff. I wouldn't spend the cash on any exotic NOS transistors  in this case. It just doesn't seem to matter much.

So, what really does matter?

There are two main parts of the circuit that determine the sound of a muff: the gain section, and the tone stack. I'm going to talk about each individually.

For the gain section, the parts you should really focus on to sculpt the sound of the Muff are the capacitors in the feedback loop of the transistors. On the GGG schematic, these are C2, C5, C6, C8, and C9. Apart from the tone stack, that's really all that makes most of the difference between the different versions. Changing these 5 caps will get you 90% of the way from a triangle to a rams a head to a Russian to a modern reissue. If you want to know what values to experiment with, those are the key. After hours upon hours of experimenting, I'm convinced that variations these caps alone account for the vast majority of what people hear to be the difference between different muffs.

Of these caps, C2, C5, and C8 are the easiest to make a choice about. Their effect is fairly minimal, but noticeable. Higher values (560pf) roll off more highs in the clipping stages and therefore make the pedal sound warmer and more "vintage." These are the values of the caps for the Triangle, Russian, and some of the early Rams Heads. To get a more modern sound that "cuts" better, use lower values (470pf) for these caps. This is the value most of the Rams Heads and later versions use. They sound more "fizzy."

The caps that overall make the biggest (and most complex) difference are C6 and C9, the caps in series with the clipping diodes. Not only do these caps affect what frequencies get clipped, they also dramatically effect the bass response and overall gain of the pedal. These caps are .1uf on reissues and many rams heads, 1uf for the second cap on some rams heads, and .05uf on the Russians and the triangle versions (and possibly some rams heads). The biggest difference in changing these values is the bass response. Using .05uf caps here lets through quite a bit more bass and makes the pedal sound much more "woolly". I think this is why a lot of people swear by the Triangle versions and why the Russian versions are so highly regarded for bass players. It mostly just comes down to these two caps. The important thing about changing these caps is that they are highly interactive, so while changing one will produce a subtle difference in tonality, changing both makes a BIG difference. If you want a more bassy sound, use .05uf here. If you want a more controlled sound use .1uf.

The rest of the sound of the muff mostly comes down to differences in the tone stack. The major variations between versions mostly boils down to R18 and R19 (GGG schematic). All of the versions have the pronounced mid scoop characteristic of the big muff, but with some subtle differences. I recommend spending some time tweaking this section because what seems like small changes can become more noticeable after getting used to the sweep and playing with it for a while. Most Muffs use 22k for R18 and 39k for R19. This produces a the most dramatic scoop. My favorite is the Triangle tone stack which swaps R39k for R18. It has a little bit less of a dramatic "scoop", but still enough that it sounds like a Muff. The Green Russian version is a bit of a different variation. It uses 22k for R18 and 20k for R19, which boosts the bass up a little, flattens the scoop, and moves the scoop up higher in frequency. It makes sense that a lot of bass players would prefer this version. Another version which has a similar curve is the GGG tuned Big Muff (same as a late 70s version). This curve also boosts the bass a bit but flattens out the curve even more. I didn't really care for the GGG tuned version because it made the Muff start to sound more like a typical distortion and less like a Muff, but some people swear by it. It's a matter of taste. I recommend socketing these two resistors so that you can experiment with values.

So that's basically it. If you want to experiment with different versions of the Muff sound, all you really have to swap are [C2,C5,C6] (fizz) and [C8,C9] (bass response), and [R18, R19] (scoop). That covers most of the tonal range from a Triangle to a Rams Head, to Russian, to modern reissue.

Other mods:

I tried a bunch of mods, but the only one that really stood out was removing the diodes (and associated cap) from the feedback loop of Q2 or Q3. This is an awesome mod that really changes the tonal character of the pedal. Removing the first set of diodes basically turns the Muff into a Colorsound Supa Fuzz, which is awesome! It completely changes the tonal character of the pedal in such a cool way. It's so easy to just put it on a switch that I think it would be silly not to include it if you were building of modding the pedal. Highly recommended!

Removing the second set of diodes produces a less usable sound, but it's still pretty cool. It's kind of a low-fi, blown speaker kind of sound, which I personally like, but this kind of thing is largely a matter of taste. I definitely recommend trying it out, at least.

Also, note that when removing the first set of diodes, the cap in series with diodes in the second loop (C9) now becomes critically important for shaping the bass response of the pedal. I found that the more vintage value of .05uf here let through too much bass. This mod sounds much better with the standard .1uf or even .22uf for C9 in my opinion.

Hope this information helps people out there. This is the kind guide I wanted when I started looking into Muffs, so I thought I'd share my findings with everyone. Happy building.

http://www.diystompboxes.com/smfforum/index.php?topic=88048.0;wap2

September 5, 2012
Big Muff Breakdown

I have been focusing on the older Electro-Harmonix Big Muffs the past few weeks and have compiled a list of changes between them. 90% of this information came from Kit's Big Muff Pi History page

I essentially want to make one pedal that can switch between the Ram's Head, V3 and the Russian. Here is what I got so far.

   Clipping / Blocking Caps – These two caps determine the bandwidth to be clipped by the diodes in the two Clipping Stages, and have the most affect on the sound of the Big Muff.

   Feedback / Filter Caps – They are responsible for how fizzy/buzzy a Big Muff will sound. Essentially they filter the amount of high frequencies in the bandwidth, determining if a Muff will sound more on the smooth side or the harsh side.

   Tone Stack Filters – Big Muffs are known for their trademark mids scooped tones, meaning the mid frequencies are removed from the bandwidth, making the sound very deep and dark.

High Pass Filter - R5 / C9
Low Pass Filter - R8 / C8

Triangle:
Clipping / Blocking:
C6 .05uF, .1uF, .12uF, and 1.0uF
C7 .05uF, .1uF, .12uF, and 1.0uF
Feedback / Filter Caps:
C10 500pF, 560pF, 470pF
C11 500pF, 560pF, 470pF
C12 500pF, 560pF, 470pF
Tone Stack Filters:
C8 27k (Early), 33k (Common)
C9 27k (Early), 33k (Common)
R5
R8

Ram's Head:
Clipping / Blocking:
C6 .047uF, .1uF, .12uF, and 1.0uF
C7 .047uF, .1uF, .12uF, and 1.0uF
Feedback / Filter Caps:
C10 560pF, 470pF
C11 560pF, 470pF
C12 560pF, 470pF
Tone Stack Filters:
C8 33k, 39k
C9 33k
R5
R8

V3:
Clipping / Blocking:
C6 1.0uF
C7 1.0uF
Feedback / Filter Caps:
C10 560pF, 470pF
C11 560pF, 470pF
C12 560pF, 470pF
Tone Stack Filters:
C8
C9 22k, 39k
R5
R8

Russian:
Clipping / Blocking:
C6 .047uF
C7 .047uF
Feedback / Filter Caps:
C10 430pF (Early), 500pF(the Civil War model), 470pF (green & black ver)
C11 430pF (Early), 500pF(the Civil War model), 470pF (green & black ver)
C12 430pF (Early), 500pF(the Civil War model), 470pF (green & black ver)
Tone Stack Filters:
C8 20k (Early), 22k (Black)
C9 22k
R5
R8



notes

   Triangle version: R1=33k, C1=4n, R2=33k, C2=10n;
   Ramshead version: R1=33k, C1=4n, R2=22k, C2=10n;
   1975 version: R1=39k, C1=4n, R2 = 22k, C2=10n;
   1977 opamp version (1): R1=5.6k, C1=100n, R2=1.2k, C2=120n;
   1977 opamp version (2): R1=8.2k, C1=100n, R2=1.2k, C2=120n;
   Green Russian version: R1=20k, C1=3.9n, R2=22k, C2=10n;
   Late model: R1=39k, C1=4n, R2=100k, C2=10n
   Reissue version: R1=22k, C1=3.9n, R2=22k, C2=10n;
   Little Big Muff version = reissue version.

Ignore the Capacitor Numbers above as they are different to the GGG ones.
http://music.codydeschenes.com/?paged=3


So I took in all that info and I had 3 rotary switches that were 3 Pole 4 Position, so I came up with this:

C6 - C9
0.047uF - 0.047uF = Triangle / Russian
0.1uF - 0.1uF = Violet Rams Head / 70's V3
0.1uF - 1.0uF = Rams Head
1.0uF - 1.0uF = Custom

C2 - C5 - C8
470pF - 470pF - 470pF = Violet Rams Head  / Russian
500pF - 500pF - 500pF = 70's V3
560pF - 560pF - 560pF = Triangle / Rams Head
220pF - 680pF - 680pF = Ram's Head Big Muff "680"

R18 - R19
22k - 20k =  Russian
22k - 39k = Rams Head
39k - 39k = Triangle / Violet Rams Head
39k - 100k = 70's V3

I organized them from low to high so they will act as increasing or decreasing whatever effect they have on the circuit.

I'm expecting the results to be quite subtle, and I can't imagine a few hundred pF on C2, C5 and C8 making much difference myself but we will see..

And I might put in some 2 pole 6 position rotary switches for some more extreme options for C6,C9 and R18, R19.
ANYONE HAVE SUGGESTIONS FOR WHAT VALUES MIGHT WORK HERE?

I thought perhaps:
R18 - R19
20k - 11.5k =  For when I use my Bass as I believe thats h what a Bass Big Muff uses?




Step 2: Modifications

I decided that I was only going to build one BIG MUFF so I wanted to add a few mods to make it cover more sounds.

First off was the 'Tone' and 'Wicker' mods from the green EH BIG MUFF:

Tone Mod

The tone mod simply bypasses the tone stack part of the circuit and will obviously disable the tone knob.

It also has the effect of giving a 6db boost in volume which I believe as the human ear hears is about twice as loud? So you can use it as a volume booster too if you like, i've seen it added as a separate  foot switch. But I wanted to keep the volume about the same and apparently adding a 150k resistor will achieve this.

Wicker Mod
I don't have a schematic for this but I believe it is simply bypassing C2, C5 and C8 on the GGG schematic. And because I've already got them being switched on one of the added rotary switches it will be even easier for me to add this


Then to add some none standard sounds I decided to add two more mods:

Mids Mod (or a version of it anyway)
This basically involves changing the values of two caps and two resistors found in the tone stack section of the circuit.
The stock circuit has a mid cut, but this mod lets you switch between Cut Mids, Flat Mids and a Mid Hump.

Since I already have the resistors on one of the rotary switches I've added I just need to put the caps on a switch.

Here Is what I decided on:

C10 - C11
0.0039uF - 0.01uF =  Scooped Mids
0.0068uF - 0.0068uF = Flat Mids
0.047uF - 0.0068uF = Mid Hump

I've seen some people just make both Caps 0.01uF and both resistors 39k for the Flat mids. But after playing with 'Tone Stack Calculator' program on the Duncan Amps website I decided to make them both 0.0068uF instead. (and because I always wondered what i'b be able to use those for)


Green = 0.01uF  Yellow = 0.0068uF
Snapshots taken with Tone knob Full Left, Full Right and Centre (which is the flat line and is same for both)
http://www.duncanamps.com/tsc/

Just seemed to make the adjustment more dramatic in the main frequency range of the guitar? I could be dead wrong on that?


Diode Mod
I didn't want to go mental with clipping diode options, so I decided to simply add a switch that will go between:

Fuzz Section 1 - Fuzz Section 2
Germanium - Germanium
Silicon- Silicon (stock)
Bypass - Silicon


So thats it really apart from adding True Bypass and a wall wort socket.



Step 3: Design

I had some 120mm x 95mm x 30mm enclosures that were given to me and I really liked the size of them so I decided to try and shoehorn it all into one of those.

I think it will fit but its really tight in some areas, so I did lots of measuring and came up with an initial design:



I've got some Laser water slide decal paper here and planned on just polishing the box up a bit then put on the water slide decal and finally a few coats of clear.

I decided to name the rotary knob selections depending on what version the selected values came from. But they will still move from lowest to highest value, left to right.



Step 4: Build
So far i've just collected most of my parts ( a couple bits to source ) and etched the PCB...
... but more on that later, Its late here and i'm going to sleep.

[nek314]

How has no one replied to this? I know the multi-muff concept is well-tread, but this project looks really great, props to you Daryl. How's it coming anyhow?

[Mark Hammer]

Thanks for the chart.

I am including a BMP in a rack unit approaching completion that has two banks of a half-dozen fuzzes,  I wasn't sure or committed enough to any particular BMP issue that I wanted to build a specific one.  So, I was going to include a few sockets for swapping a few select components to get different issues.  Your table is going to help me determine what the maximum flexibility for the minimum number of socketed pieces will be.

So thanks again! 

[nocentelli]

Excellent thread, and that graphic is great!

I feel rotary switches have pro's and con's: For a super-BMP, the big pro is that you can assign a name to each position, e.g. a switch that selects different values for the clipping caps can have those "Russian"  and "Triangle" settings etc.

The downside of switches is of course you only get fixed values: Since switches and pots both occupy the same amount of space, I tend to think the flexibility of a pot trumps the specific value designation of a switch, and if you prefer the idea of being able to dial in a blend of different values rather than setting it with switches, it's worth having a look at the schematic for the new version of the Way Huge Swollen Pickle. Including internal trimmers, it's got something like seven pots that cover many of the variables discussed in this thread.

[facon]

Man, thanks for posting this!

[Resynthesis]

Nice ,thanks.

You might also be interested in Kitrae's excellent compilation of Muff schematics

http://www.bigmuffpage.com/Big_Muff_Pi_versions_schematics_part1.html

[Xander8280]

Very cool

[toneman]

Hey Resynthesis, thanks for that link!!

[kodiakklub]

oh my god i walk away from building pedals for a few months and this message board and someone comes along and makes the exact same spreadsheet and pedal as me!!?? 

daryl, we have to join forces. ive been working on this for about a year. now i have to go back and read your OP cause i just saw the spread sheet multi-colored just like i did and my jaw hit the floor. ive been through 3 revisions of PCB's. none working thus far. but i can tell you what parts have any bearing on tonal difference. and really there arent many. gonna go read your whole post not though....

[kodiakklub]

https://docs.google.com/spreadsheet/ccc?key=0AsT5EU8KLtaYdHA4UHZSeDhNbkV2MTFsYzM0ZjljVVE

this is my version of the spreadsheet. i cut out the early years actually now looking at it for the first time in probably 4 months. mine is going to have a second 3PDT for a huge boost and 3 or 4 switches. and it has a second tone knob that interacts with the main tone knob. the first version i did to test out some of these theories was with using a madbean muff copy board. that one works, but i havent been able to get one of my own layouts working yet.

[kodiakklub]

i changed the permission for the link to my spreadsheet. now its public.

[daryl]

Great to see i'm not the only one. I wanted to do this as an exercise in learning how the effects actually work, what makes a difference in a circuit and why, instead of just blindly following schematics.

I started with the GGG PCB layout which I thickened up the traces slightly before I etched it : http://www.generalguitargadgets.com/pdf/ggg_bmp_vram_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Then I did all the mods off board, soldered direct onto the switches and rotarys.

Then I built the whole pedal, but was having issues and there was so much going on it was impossible to debugg.

So I stripped it down to a standard GGG Violet big muff, and got that working ok.

Now i'm adding the mods back on one at a time so I can make sure its all working, that way I will know whats causing the issues.

So far i've just added the clipping caps rotary knob that alters C6 and C9 on the GGG schematic: http://www.generalguitargadgets.com/pdf/ggg_bmp_vram_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
I can hear that it alters the amount of bass / treble but its very subtle. I've only tried it on my practice amp though so it might have more of an effect on my valve amp with 4x12, will let you know.
---
I can post pics if anyone is interested.

Question
If I want to bypass the first clipping stage do I:
a) just jumper across the diodes
b) jumper the diodes and cap
c) cut between the diodes and the cap

[LucifersTrip]

Question
If I want to bypass the first clipping stage do I:
a) just jumper across the diodes
b) jumper the diodes and cap
c) cut between the diodes and the cap

if you truly want to bypass it, you have to disconnect c4, c7, r9, r11 and r12...and connect stage 1 directly to stage 3

btw, since you really are going nuts with this, I thought I'd mention my favorite "mod" (not really)...and that is to use all transistors with hfe's < 100. I built a Triangle that way (except Q4 ~ 125) and is my favorite so far...Remember, in the early versions, the transistors most likely don't have high hfe's at all. I think they were those old button types.

good luck with the project!

[daryl]

What i was trying to figure out is what the 'Wicker' mod is ? on the new green ones  with 'tone' and wicker' switches.

[LucifersTrip]

What i was trying to figure out is what the 'Wicker' mod is ? on the new green ones  with 'tone' and wicker' switches.

that's a totally different question

http://www.diystompboxes.com/smfforum/index.php?topic=85623.0;wap2

[daryl]

yeah I know It was late and I got confused.

I'm tyring to do two things that I havent got figured out yet.

1) Is what is suggested here:

I tried a bunch of mods, but the only one that really stood out was removing the diodes (and associated cap) from the feedback loop of Q2 or Q3. This is an awesome mod that really changes the tonal character of the pedal. Removing the first set of diodes basically turns the Muff into a Colorsound Supa Fuzz, which is awesome! It completely changes the tonal character of the pedal in such a cool way.

2) is the 'Wicker' mod.

[daryl]

Wicker MOD:

dune2k:
The first three transistor stages all have caps to roll of treble in them.
You only have to break the connection on one side of the cap to lift them out of the circuit.

The rest should be easy to figure out.

Cheers for the link.

I can see where I went wrong now, I jumpered them instead of disconnecting them.

[kodiakklub]

what is the correct method to suppress the POP when switching between caps in the live circuit? and resistors for that matter....ive tried a few things and none have worked.

[kodiakklub]

and since i have Eagle open, here's my most recent schem for my mega muff project. i would love for as many people to look it over for any glaring mistakes. this is my first circuit that i have changed a lot and it's still not functional. no noise of any kind. just dead. im thinking im grounding out caps and resistors in an effort to suppress the POPS. thanks all.

[daryl]

I'm not getting any pop and i'm not doing anything special.