Big Muff in Small Spaces

[Mark Hammer]

Vertically-mounted resistors, and small pots mounted to the board, can circumvent a lot of lead dress/crosstalk issues. The caveat is that if one uses vertically-mounted resistors, and mounts the pots to the chassis, you need to be careful about the bent resistor leads not shorting out against the back of the pots....one of the many sources of "I don't get it. It was working fine before I boxed it up".

[David Schwab]

MUFF! MUFF! MUFF! MUFF! MUFF! MUFF! MUFF! MUFF! MUFF!

There. Let's get it all out in one shot

Oops, now I'm flying off the rails.

Let's get the name right...

The pedal is called the "Big Muff Pi"

Muff Pie = Fuzz Box.

On another note, I hate these new really small pedals with no batteries. I don't use a pedal board or power supplies.

[Dave99]

Hi! I'm interested in your project and would like to recreate that pedal too! But I've got a quesion... Why is there a 100uF electrolytic capacitor between ground and +9v power? IMHO toy should connect ground to the ground of the jack and to the "-" of the battery, then +9v to the "+" of the battery... Cn you explain me please? Thanks a lot.

[Enzo]

Hi Dave

Post 4 has a schematic, but I don't see a 100uf across the 9v. Please link the schematic you are considering.

A filter cap is across the power input to many pedals for two reasons. One is that if an external 9v supply is not sufficiently filtered, the cap will help smooth the power. But it also serves as decoupling, to prevent signal from riding the power rail to other stages. Putting a cap across the supply really doesn't affect how the battery is wired.

[Dave99]

Hi Enzo

I refer to the pic of the pcb reported in post 1, not the schematic in post 4. In the pcb I mean ground is the thickest "cable" which go along bottom and left edges of the pcb; +9v is the "cable" on the bottom edge, just over the gnd. And on the left i see a 100uF capacitor, I think electrolytic, which connect these 2 "cables" (don't know their names in English, sorry )

[Enzo]

Oh, if it is 100uf, count on it being electrolytic.


OK, I see that. What I said stands. It is a filter/decoupler across the 9v supply on the board. It really has nothing to do with how the jacks and battery are wired though.

[Dave99]

Oh, now I understand...
So, I have to connect this cap from the gnd to? The 9v+ or "-" of the battery? Imho it should be wired as this if it's a filter:

Am I right?

[Enzo]

Just pretend the cap isn't there. COuld you wire it then? The cap doesn't change anything, it just improves performance of the circuit.

No, your diagram is not correct. The battery plus would go the the 9v trace on the board. The minus side of the battery would not go to the plus terminal of the cap.

If you hard wire the battery to the circuit, it will always be on, and the battery will wear down. You need to wire up the input jack to complete the battery ground like a zillion other pedals. Wire +9 to the +9 rail on the board, wire -9 to the ring contact of a TRS jack. Then when you plug a guitar cord into it, the shaft of the plug grounds the battery minus, completing the circuit.

[Dave99]

Ok... So like this:



(I'll made something to do that the battery go to the voard only when you plug in the in jack, as you said, and I'll add the 3pdt switch...)
But so where does the filter cap go? Between board and "-" or between board and "+"? and where does the "+" of the cap go?
Thanks a lot

[Enzo]

I am not sure where we are not yet communicating. The cap does not connect between the board and anything, it is just on the board. Its positive end is wired to the +9 trace, and the negative end is wired to the board ground. Period. Like I said before, just pretend it isn't there, and wire up your pedal. The cap is simply wired to +9 and ground right on the board.

Yes, wire the battery +9 to the +9 on the board. The input jack should be a TRS jack - what some call a stereo jack. TRS means tip, ring, sleeve. The battery negative is wired to the ring contact on that jack

[Dave99]

Ok ok, I can understand what you said before now... But:
1. Are you sure that a cap between + and ground (which is -, right?) doesn't do a black out (not sure if it's the correct word in english)?
2. What happens if I connect a stereo jack in the input? The battery cannot power on the board, right? Or will that damage th effect?

Sorry for all these questions but it's the first effect pedal I make...

[Jazz P Bass]

Ok ok, I can understand what you said before now... But:
1. Are you sure that a cap between + and ground (which is -, right?) doesn't do a black out (not sure if it's the correct word in english)?
2. What happens if I connect a stereo jack in the input? The battery cannot power on the board, right? Or will that damage th effect?

Sorry for all these questions but it's the first effect pedal I make...

The capacitor + terminal connects to the +9Volt buss of the pc board.
The capacitor - terminal connects to the - (ground) buss of the pc board.

Think of it as simply being attached to the battery, although the connections are on the pc board.

Wire the TRS (stereo) jack as Enzo stated.
When you connect a TR (mono) instrument cable, tha long Ring terminal of the plug will connect the RS terninals of the jack.
That way the battery circuit will not be ON until you connect the instrument.

[elipsey]

The muff is a great project. You can add an LED, true bypass and better power switching than the original. I built the tonepad one, and changed a few parts to match my original triangle muff -- same sound, but more practical in my opinion. My original had smaller value coupling caps that made it just a little less bass heavy then modern muffs, and most clone schematics, so I used the smaller values in the clone as well.

I strongly encourage you to go to tonepad.com and check out the various power switching and bypass diagrams, lots of ideas there that wouldn't have occurred to me.

Here are pics, I hope they provide you with some muffspiration. Good luck, have fun.

[Dave99]

Great work elipsey!
Just a thing I wanted to know: how to print/draw on the chassis? I mean, what type of colour do I have to use?
Now I'm not at home, when I get back I'll post a pic of my idea of wiring and I was wondering if you could tell me if it is true bypass... Thanks!

[g1]

2. What happens if I connect a stereo jack in the input? The battery cannot power on the board, right? Or will that damage th effect?

Correct, the unit will not turn on, no damage will be done.