death by audio - germanium filter

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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tomeunknown
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Post by tomeunknown »

some gut shots that might be of interest! :)



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tomeunknown
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Post by tomeunknown »

Another clearer pic:


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Post by tomeunknown »

Hey! .. some movement from a ‘redditor’ over at the diypedals subreddit.

Hopefully this ignites some momentum!


https://www.falstad.com/afilter/

Copy below and go to ‘insert from txt’


$ 1 0.000005 5 50 5 50
% 0 20615.097787781793
c 112 144 112 192 0 4.7000000000000004e-8 0
r 64 144 112 144 0 33000
O 144 112 256 112 0
g 112 192 112 208 0
170 64 144 32 144 3 20 1000 5 0.1
174 112 144 144 80 0 500000 0.9950000000000001 Resistance
c 112 80 64 80 0 1e-9 0
w 64 144 64 80 0
r 112 80 160 80 0 33000
c 160 80 160 32 0 2.2000000000000003e-9 0
g 160 32 192 32 0
o 4 16 0 34 5 0.00009765625 0 -1 in
o 2 16 0 34 2.5 0.00009765625 1 -1 out

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graybench
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Post by graybench »



MOSFET boost (similar to SHO) > inverted PNP germ gain stage > Fuzz War II tone control (mostly) > inverted PNP germ gain stage (collector bypassed 2.2u).
Gain: B50K, Tone: A500K, Volume (trim pot): 100K

Enjoy!

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tomeunknown
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Post by tomeunknown »

Amazing..! Ideally someone that knows more than me can whip up a layout off the back of your dissection!

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mdcmdcmd
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Post by mdcmdcmd »

I'm pretty sure those MP10B transistors are NPN, not PNP.

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Post by Jarno »

That would explain the absence of some integrated circuits.
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graybench
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Post by graybench »

mdcmdcmd wrote: 04 Apr 2022, 14:53 I'm pretty sure those MP10B transistors are NPN, not PNP.
Ughhh you're right, I mistakenly assumed it was PNP because it was one of the soviet Q's. Most I've dealt with have been...
That will make the schematic more comfortable to read at least :)

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Post by Sesh »

graybench wrote: 29 Mar 2022, 13:56

MOSFET boost (similar to SHO) > inverted PNP germ gain stage > Fuzz War II tone control (mostly) > inverted PNP germ gain stage (collector bypassed 2.2u).
Gain: B50K, Tone: A500K, Volume (trim pot): 100K

Enjoy!
Thank you so much for the teardown! Very interesting.

While a work-a-like is definitely doable, knowing DBA, it most likely is a "twisted" take on a gain stage. They call it a "drive circuitry in the style of classic recording consoles". Just like the Hudson Broadcast, I note. That one was inspired by "old RCA consoles". Perhaps the BA-71 preamps?

Perhaps someone - more of an electronics wiz than I - could make a schematic that combines an SHO (https://external-preview.redd.it/dKsAR- ... b8d928eff4) into a germanium console stage from something like a RCA ba-71 (http://www.jlmaudio.com/RCA/BA-71A%201024.jpg) into the fuzz war mk 2 filter (https://www.pedalpcb.com/docs/BellumMKII-PedalPCB.pdf) into yet another ba-71 stage...

I'm sure mr. Fuzzhead/Dirtboxlayouts.blogspot.com would be willing to do the vero.

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Post by tome.talevski »

Sesh wrote: 05 Jul 2022, 13:01
graybench wrote: 29 Mar 2022, 13:56

MOSFET boost (similar to SHO) > inverted PNP germ gain stage > Fuzz War II tone control (mostly) > inverted PNP germ gain stage (collector bypassed 2.2u).
Gain: B50K, Tone: A500K, Volume (trim pot): 100K

Enjoy!
Thank you so much for the teardown! Very interesting.

While a work-a-like is definitely doable, knowing DBA, it most likely is a "twisted" take on a gain stage. They call it a "drive circuitry in the style of classic recording consoles". Just like the Hudson Broadcast, I note. That one was inspired by "old RCA consoles". Perhaps the BA-71 preamps?

Perhaps someone - more of an electronics wiz than I - could make a schematic that combines an SHO (https://external-preview.redd.it/dKsAR- ... b8d928eff4) into a germanium console stage from something like a RCA ba-71 (http://www.jlmaudio.com/RCA/BA-71A%201024.jpg) into the fuzz war mk 2 filter (https://www.pedalpcb.com/docs/BellumMKII-PedalPCB.pdf) into yet another ba-71 stage...

I'm sure mr. Fuzzhead/Dirtboxlayouts.blogspot.com would be willing to do the vero.
Any movement or interest on some of these ideas?

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Post by andare »

This is what I traced from screenshots taken from graybench's excellent video. Obviously I have no idea what I'm doing, in way over my head here :)


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Post by soggybag »

andare wrote: 21 Apr 2023, 21:00 This is what I traced from screenshots taken from graybench's excellent video. Obviously I have no idea what I'm doing, in way over my head here :)

I think C2 is upside down. The positive leg should ho to 9v.

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Post by andare »

You're right!

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Post by Fuzz_Mountain »

Is there a verified schematic for this one out there?

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Post by andare »

Fuzz_Mountain wrote: 15 May 2023, 16:19 Is there a verified schematic for this one out there?
don't think so. AFAIK there's only mine above, which is probably incorrect and missing the output. Someone should breadboard it and see, at the very least. Hopefully someone with access to a unit can trace it properly.

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