Germanium Transistors in Big Muff Circuit.

[VimEFX2017]

I'm pretty sure there is at least on post like this but still new to this site.

I have about 200 NOS MP42B (2N123) Russian transistors and I plan to use them for some fuzz and over drive pedal builds. Has anybody had any success with using Germanium transistors in a BMP? If so what was done to accommodate the transistor change other than changing the polarity of the battery.

**To get it out of the way ahead of time. I know the diodes and tone control do more than the transistors in this circuit.
Thanks ahead of time.

[Plexi]

There you go :-)
http://www.bigmuffpage.com/images/schematics/KITS%20V1%2072-2%20SCHEMATIC.jpg
You must to flip all polarized components: not clipping diodes.

Sometimes the hfe can be a good change in the BM, like in the Hoof.

[Kennt82]

I just built a Hoof, which uses germanium transistors for the 2 clipping stages.  The Frantone Sweet uses them for the clipping and recovery stages.

You can also experiment using those transistors of yours as clipping diodes.

[duck_arse]

there is a thread ..... there always is.
http://www.diystompboxes.com/smfforum/index.php?topic=109007.0

you might need to hit-up dino for some images.

and welcome to the forum.

[digi2t]

I'll re-up the images tonight.

For the record, all germanium wasn't a hit to my ears. It was VERY hissy. But, using all germanium in the clipping sections, and silicon as the engine and caboose, is great. All the right Muff tones, but with that germanium "orgasmic organic" feel.

[digi2t]

Here y'all go...













Sorry about the super huge photos, I'm still getting the hang of Imgur.

[VimEFX2017]

Can you explain the 4004 diode that replaces the resistor to ground in the Fuzz stages? and Thanks for the Schematic.

[Plexi]

I have a few 2SB54 from the failed TB MKII...and now I HAVE to try this

Enviado desde mi HUAWEI Y600-U351 mediante Tapatalk

[digi2t]

Can you explain the 4004 diode that replaces the resistor to ground in the Fuzz stages? and Thanks for the Schematic.

[VimEFX2017]

Sweet, thanks all

[mac]

Best germs I tried for this are Matsushita 2sb176.
, Hfe 200.
2sb54 are also very good but have less gain.

In my gallery you can find the schem above and a sound clip.

mac

[digi2t]

Best germs I tried for this are Matsushita 2sb176.
, Hfe 200.
2sb54 are also very good but have less gain.

In my gallery you can find the schem above and a sound clip.

mac

Confirmation on that, and is what I ran with on mine. Tried a bucketload of different germs, Japanese, Russian, and others, but the 176'ers rawk.

[Plexi]

Best germs I tried for this are Matsushita 2sb176.
, Hfe 200.
2sb54 are also very good but have less gain.

In my gallery you can find the schem above and a sound clip.

mac

Sure..you're right Marce!
I'll try at least to use them in the clippimg stage, and use something like BC560C on input and recovery stages.

[mac]

IIRC a silicon at the input was suggested for noise issues. Germs are noisy.
But for the record, I did not have problems with mine.

I'll try at least to use them in the clippimg stage, and use something like BC560C on input and recovery stages.

Hybrid cars, why not hybrid pedals!

mac

[Plexi]

IIRC a silicon at the input was suggested for noise issues. Germs are noisy.
But for the record, I did not have problems with mine.

I'll try at least to use them in the clippimg stage, and use something like BC560C on input and recovery stages.

Hybrid cars, why not hybrid pedals!

mac

Sure, why not?
I was thinking, before read your answer: would be possible to have NPN-PNP-PNP-NPN in this case?
I think would be possible if the PNP/clipping stages are flipped down.

Am I right?

[teemuk]

Most of the transistors are inside a closed negative feedback loop so their contribution to circuit performance is negligible as long as the stages bias about right. In addition, the signal voltage swing is clamped by diodes in the feedback loop so transistors contribute absolutely nothing to clipping.

IMO, using germanium transistors just introduces horrible temperature coefficiency.... and more hiss.

I'd stick with silicon. If you want some "germanium overdrive" then replace the clipping diodes in the feedback loop. That's a way more sensible decision.

[Plexi]

Good advise, teemuk.
Cap and resistor (~470k) used in parallel with clipping diodes on each stage can reduce gain.
Especially the feedback (B to C) on each transistor: reducing value to reduce gain.
The feedback cap will roll-off highs (and kill 'crunch'): increase it will get a more 'round sound.

Hoof have LEDs in this stage in conjunction with Ge: I guess that way it bump all the mid-highs that was lost with the low gain transistors.

[mac]

I did not notice a hugh thermal runaway in this particular project.
Just breadboard a stage and heat the transistor with your fingers or hair dryer, and measure the deviation.

I was thinking, before read your answer: would be possible to have NPN-PNP-PNP-NPN in this case?
I think would be possible if the PNP/clipping stages are flipped down.

Yeap.
But given this is a very high gain circuit, and electrons can do strange things sometimes, if you have oscillations, etc, some decoupling from the PS might be needed between stages.

On second thought, why not all PNP? PNP Silicons 2n5087 or bc559?

mac

[Hatredman]

"hugh thermal runaway" is a great name for a pedal. Specially the Hugh part.

Scarlett Johansson uses a Burst Box with her Telecaster.

[Plexi]

I did not notice a hugh thermal runaway in this particular project.
Just breadboard a stage and heat the transistor with your fingers or hair dryer, and measure the deviation.

I was thinking, before read your answer: would be possible to have NPN-PNP-PNP-NPN in this case?
I think would be possible if the PNP/clipping stages are flipped down.

Yeap.
But given this is a very high gain circuit, and electrons can do strange things sometimes, if you have oscillations, etc, some decoupling from the PS might be needed between stages.

On second thought, why not all PNP? PNP Silicons 2n5087 or bc559?

mac

Sure... just my idea was to know "what happen if..." the 4 stages where combined, to - ground.

Off: Can I ask you, Hatredman, why your signature is "Scarlett Johansson uses a Burst Box with her Telecaster."??