EHX - Germanium 4 Big Muff Pi EC- D66 revision C [schematic]

[GodSaveMetal]

I have this for the next few days. I'll answer any questions or take more pictures of anything while I have it.

[GodSaveMetal]

Germanium Transistors - NKT275
Q5 - PN2222A
U1, U2 - Tl072
D3 - SS14

Pots:
Distortion Side:
Gain - A100K
Volume - A100K
Bias - 10KB
Volts - 10KA

Overdrive Side:
Bias - 100KB
Gain - 100KC
Tone - 100KB
Volume - 100KB

[sinner]

Hard to be sure looking on pictures, but are the germaniims are in darlington pairs located in clipping srages only?

[sinner]

Fucking phone browiser...

[Bside2234]

At quick glance the Distortion side has them as clipping diodes in a feedback loop. The OD side looks to be a little different.

[azrael]

No interest in this?
Maybe these will spark some interest. I did a quick trace through it and came up with these schematics.
They aren't verified and I'm sure there might be some mistakes as I only had about 30 minutes to do it.
I still have it so if you want me to verify any connections or values, I can do that.

[azrael]

Weird, how could this be called a Big Muff?

[Bside2234]

Weird, how could this be called a Big Muff?

That's exactly what I said! It's totally different than what I was expecting in there.

[devastator]

Weird, how could this be called a Big Muff?

just to sell more pedals

intersting design.

I don't understand the feedback loop of U2b in the distortion side. I'd say that the Ge transistors are used as diodes but what about the "bias" knob after ?

the overdrive side seems unusual !

[Kitrae]

Weird, how could this be called a Big Muff?

By placing "Germanium 4" in front of "Big Muff"

I thought it was a bit odd to use that name too, but it was designed by Bob Myer, the guy who designed the original, so maybe they thought it made sense. Nothing BMP'ish about the sound. Some interesting stuff going on in that schematic though.

[somnabula]

Some more context on the design of this pedal: http://www.kitrae.net/music/big_muff_history3.html

I have one of these at home and one can get a lot of different yet great sounds out of this one.
Especially the bias and volts knobs make this an interesting one and both could be added to any distortion/od pedal.

[somnabula]

Some more context on the design of this pedal: http://www.kitrae.net/music/big_muff_history3.html

I have one of these at home and one can get a lot of different yet great sounds out of this one.
Especially the bias and volts knobs make this an interesting one and both could be added to any distortion/od pedal.

Ha, and now I see I just linked to Kitrae's website.

Great site though.

[iznogoud]

You made my day, dude!
I was about to retrace my BM Ge4 in order to put it, with several other stomps, in a 19' rack enclosure to complete my compact mini-rig of doom (Triaxis/MPX G2/Eclipse/Marsh 20-20/Switchblade GL) and not having to mess with a big pedalboard. It will avoid losing time at doing it.

I personnally think the BM Ge4 is really a great stompbox and at a right price : it's useless to build a clone except if, as me, you need some re-casing in another format. You can't really tell it's a BigMuff, the sound has nothing common with these series, but it's a real fuzz lab being able to issue most of the classic Ge fuzz sounds without becoming mad with bizarre results. In fact, this one would deserve more the Fuzz Factory name than the Zvex (which is very interesting but not easy at all to use)

[devastator]

there're some things odd on the schematic actually . The power supply of the distortion side shows a 1nF cap in series with V+ . The feedback loop around the op-amp seems strange too.

Iznogood ( also obelix2 I guess ) could check on yours ?

[Bside2234]

there're some things odd on the schematic actually . The power supply of the distortion side shows a 1nF cap in series with V+ . The feedback loop around the op-amp seems strange too.

Iznogood ( also obelix2 I guess ) could check on yours ?

I still have mine. When I get a chance I can go through it again and check.

[devastator]

the fact is that the transistor used in the volt circuit reminds me a classical stabilizer transistor :



With some arragements , the zener diode replaced with a pot.

If it's not the kind of circuit , it should a typical transistor buffer (the variable voltage comes into the base and the voltage goes out via the emmeter ).

is it connected to the power supply of the TL072 ?

[modman]

Here are the schematics I drawn. I hope it would help someone.

[modman]

I'll edit the previous post when possible.

[DarthKaker]

Lemic could you Please attach once more this schematic?

[bopelado]

Lemic could you Please attach once more this schematic?

did you get the schematic? is not verify