Death by Audio Germanium Filter

I think I've accounted for anything that is visible. I can't see a cap after Q3 and I can't see where the output is. Output cap also missing. This is fun and I learned a lot but I guess it's better left to the pros. I'm sure this will be traced properly sooner or later.

DBA Germanium Filter Schematic.png
 
Wow, cool thread to stumble onto.

I love the DBA pedals I've built this far so I'd love to have this one.
 
anders said:
I have a DBA Germanium Filter on my desk at the moment. So I decided to trace it and hopefully I got it correct.
The protection diodes are still unknown but they both meassure at 0,57 v.d (in circuit).
Click to expand...
You made my day! I literally spent hours yesterday trying to fix my broken trace and gave up cause I don't even know what I'm looking at in the gutshots.
It's fun to see how wrong I was :)

I know what I'll be breadboarding next. Thanks!
 
andare said:
You made my day! I literally spent hours yesterday trying to fix my broken trace and gave up cause I don't even know what I'm looking at in the gutshots.
It's fun to see how wrong I was :)

I know what I'll be breadboarding next. Thanks!
Click to expand...
Yours was getting close. That there was no output in it made it seem suspect though ;).
 
A friend of mine built this based one the schematic above. Transistor selection is importatant here.
You'll need some really low gain and low leak NPN Ge's in the Hfe 20-30 range. Higher gain transistors will not sound good in low gain settings and the gain control won't react as in the original units. Low gain silicon works as well.

I guess I need to dive into box of "duds" or selecting some low gain MP37s or MP38s before I tackling this one.
 
anders said:
A friend of mine built this based one the schematic above. Transistor selection is importatant here.
You'll need some really low gain and low leak NPN Ge's in the Hfe 20-30 range. Higher gain transistors will not sound good in low gain settings and the gain control won't react as in the original units. Low gain silicon works as well.

I guess I need to dive into box of "duds" or selecting some low gain MP37s or MP38s before I tackling this one.
Click to expand...
Well done man! Your comments brought to mind something I saw listed earlier. Not what I need right at this moment but could be the ticket for folks looking to make this. https://www.ebay.com/itm/2556132720...meivpjoss-&var=&widget_ver=artemis&media=COPY

EDIT: Side note, I see DBA calls the first boost section a “console style boost”, and of course with it being a very SHO like circuit I guess that tracks given ZVEX claims the SHO is a console style boost but I’m curious what “console” uses a front end like that. I’ve looked at a LOT of old audio schematics but never ran across it
 
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