Big Muff total gain

[JaviCAP]

Hi mates,

As you know, the Big Muff is one of my favourite pedals, and i've built tons of them and own a few versions.

We have discused many times if the trannies hfe is key in the final gain / sound of the effect, and after many builds, I can confirm that the model / hfe of the trannies, is the less important thing in this board.

Let's see: the gain of a BMP is determined by the ratio collector- emitter in the three first stages (the last one is just to recover the output lost on the tonestack), so we just have to divide collector value by emmiter value of each stage, and sum the final values to get a "gain factor".

If we check a green russian, known for being maybe the less gainy big muff we find the next values:

Q1: C: 12k E: 390r= 12000/390= 30,75
Q2: C: 12k E: 390r= 12000/390= 30,75
Q3: C: 12k E: 390r= 12000/390= 30,75

Total gain factor= 92,25.

Now, let's see the most monstruous gain Big Muff, the first version of the Triangle (besides, originally built on perfboard :P)

Q1: C: 39k E:120r=  39000/120= 325
Q2: C: 10k E:120r=  10000/120= 83,3
Q3: C: 39k E:120r=  39000/120= 325

Total gain factor: 733,3

Of course, there are more components that affect the total gain of the effect. but let's say that 95% of the total drive, comes from thjis point.

I've built this weekend the Triangle V1, and really, the gain is absolutely massive. I've used 2n5088, BC550C, BC109C, 2N3904, ME4003, and believe me: the sound was nearly exact with every different trannie used. I even put one different in each position, with same results. Had to use MPSA07, extremely low gain (between 80-90 hfe), to get a farty and with few sustain sound.

So, from my experience, while using > 300hfe trannies, the Big Muff will sound great. Don't forget that the Swollen Pickle is just a tweaked Big Muff that uses 4x 2N3904, and it's a really harsh and high gainy effect.

By the way, for Zach and other bassists: if you love the Green Russian, just try the Triangle V1, you'll be amazed. The brutal gain factor + the intensive use of 1uf + 0.68uf caps + 27k tonestack resistors, get the most gainy and compensated between bass - mids -highs that I've listened, even thought is go high gain that can become a bit muddy on guitar.

J.

[IvIark]

Great info mate.  Build a Fuzz Moo and see what you think!

[JaviCAP]

Thanks mate, i'll build it, but I'm running short of b100k pots. Just ordered yesterday 40 pieces more, when they come. Ill build the Moen :P

J.

[IvIark]

[Frank_NH]

Here's a link with some information about the Big Muff Circuit that is helpful for understanding how it works:

Electrosmash - Big Muff Pi Analysis

I suppose the thing to remember about gain in this kind of circuit is that the diodes in the gain stages clip the signal, and thus cap the voltage gain.  However, the hfe of the transistors will impact the nature of the clipping as shown in the Electrosmash analysis.

I haven't built a Big Muff yet, and was thinking about doing a vero with sockets for all of the important caps, resistors, diodes, and transistors.  That way, you could try out different components to tune the sound to your liking.

[rocket88]

I'm shocked Frank that you haven't built a big muff yet.  I've had similar experiences to Javi s, when trying different transistors. I find that there are slight differences, mostly in the amount of compression. Also, to my ears the higher the hfe the more treble it seems to have, but if you go below 300hfe, that's when I start to hear the fartiness.

There's this site that talks about how each mod affects the big muff, which I find or be fairly spot on.

Also, Javi the V1 big muff has been on my list for awhile. I think after the lab is all set up it's going to be my second build, after I get the bbbod done. Off topic, did you build the opamp muff posted with 2 dual ICs instead of 1 quad? Completely different animal the the transistor muffs, and changing ICs can make a massive difference in sound and gain.

[JaviCAP]

Yeah, I built the 2 ic's one.

Quad is not a good idea in the IC Big Muff. For a start, I don't like to use a quad when is not an exact double version of the needed IC, for examlpe: using a TL074 when the schematic asks for 2x Tl072 it's ok, but a TL074 instead 2x 4558 is not ok.

When I built the IC BMP, using the quad, I liked the results, but it was not the sound I was looking for, so used a layout with the two IC's, a 4558 and a 741, and the difference is HUGE. JRC 4558 gives more color to the sound than the TL072, and a 741 is a must in this circuit: harsh, noisy and really more suitable for a "fuzz like" circuit.

Sure, the IC Muff is a different animal but... it sounds too like a Big Muff, different sound,  somehow smoother, and great for rythm guitar.

J.

[rocket88]

Knowing you, I figured you would have built it. Glad to hear the results I got were the same as you. I tell you the big muff is not a fair pedal. Due to all the different versions, and each one is different, I just have to build each one. And god only knows what the next will be, all I know is it will be different from the present.

[JaviCAP]

I bet you'll like it, Zach :P In the picture is not present the '76 PNP and another '73 in desk -box (like the Triangle). Once I box the Triangle V1, I'll take a new family pic :)

Just need to build now the Black russian and the Civil War!



J.

[Frank_NH]

"I'm shocked Frank that you haven't built a big muff yet."

Yes - It's TRUE!  

(And I haven't built my first Klon yet, either!  I feel so incomplete... )

BTW - I have a Muff PCB and all the parts, so I'll getting to that at some point.  I'm going to go for the Swollen Pickle version.   I suppose my delay in building a Muff was because I have already built a Univox Superfuzz clone...and that one is GOOD, especially the scooped sounds!  Alas, it's not a Muff...

[dbat69]

That is a nice collection of Muffs, Javi

And thank you for the information, this will be very useful

[Vince]

Great info Javi.... I've also done some Muff fiddling (here come the muff puns) and found the resistor mods to drastically increase gain (see link). Also using 1N4001's seems to compress more but I like the 1N914's as they seems a little more 'open'.

http://stompage.juansolo.co.uk/Muffs.htm

http://rkerkhof.ruhosting.nl/Taas/Mods/Big%20Muff.htm