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

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EHX - Germanium 4 Big Muff Pi EC- D66 revision C

Postby Bside2234 » 18 Nov 2012, 21:57

I have this for the next few days. I'll answer any questions or take more pictures of anything while I have it.
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Re: Big Muff Germanium4 [Guts]

Postby Bside2234 » 18 Nov 2012, 22:04

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

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Re: Big Muff Germanium4 [Guts]

Postby sinner » 18 Nov 2012, 23:06

Hard to be sure looking on pictures, but are the germaniims are in darlington pairs located in clipping srages only?
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Re: Big Muff Germanium4 [Guts]

Postby sinner » 18 Nov 2012, 23:08

Fucking phone browiser...
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Re: Big Muff Germanium4 [Guts]

Postby Bside2234 » 19 Nov 2012, 00:14

At quick glance the Distortion side has them as clipping diodes in a feedback loop. The OD side looks to be a little different.
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Re: Big Muff Germanium4 [Guts]  [schematic]

Postby Bside2234 » 19 Nov 2012, 18:53

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.
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Re: Big Muff Germanium4 [Guts]

Postby azrael » 20 Nov 2012, 17:43

Weird, how could this be called a Big Muff? :P
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Re: Big Muff Germanium4 [Guts]

Postby Bside2234 » 20 Nov 2012, 19:14

azrael wrote:Weird, how could this be called a Big Muff? :P


That's exactly what I said! It's totally different than what I was expecting in there.
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Re: Big Muff Germanium4 [Guts]

Postby devastator » 20 Nov 2012, 21:38

azrael wrote:Weird, how could this be called a Big Muff? :P


just to sell more pedals :mrgreen:

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 !
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Re: Big Muff Germanium4 [Guts]

Postby Kitrae » 21 Nov 2012, 19:18

azrael wrote:Weird, how could this be called a Big Muff? :P


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.
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Re: Big Muff Germanium4 [Guts]

Postby somnabula » 22 Nov 2012, 10:58

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.
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Re: Big Muff Germanium4 [Guts]

Postby somnabula » 22 Nov 2012, 11:00

somnabula wrote: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. :oops:

Great site though. :)
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Re: Big Muff Germanium4 [Guts]

Postby iznogoud » 23 Apr 2013, 09:48

You made my day, dude! :hug:
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. :applause:

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)
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Re: Big Muff Germanium4 [Guts]

Postby devastator » 02 May 2013, 20:22

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

Iznogood ( also obelix2 I guess :lol: ) could check on yours ?
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Re: Big Muff Germanium4 [Guts]

Postby Bside2234 » 02 May 2013, 21:23

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

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



I still have mine. When I get a chance I can go through it again and check.
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Re: Big Muff Germanium4 [Guts]

Postby devastator » 02 May 2013, 22:42

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

Image

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 ?
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Re: Big Muff Germanium4 [Guts]

Postby Lemic » 19 Feb 2014, 22:56

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

Image
Image
Image

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Re: Big Muff Germanium4 [Guts]

Postby Lemic » 20 Feb 2014, 09:27

I'll edit the previous post when possible.
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Re: EHX - Germanium 4 Big Muff Pi EC- D66 revision C

Postby DarthKaker » 22 Feb 2016, 10:58

Lemic could you Please attach once more this schematic? :)
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Re: EHX - Germanium 4 Big Muff Pi EC- D66 revision C

Postby bopelado » 22 Nov 2017, 19:41

DarthKaker wrote:Lemic could you Please attach once more this schematic? :)


did you get the schematic? is not verify
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