Box of Germanium

[anders]

I have a tons of USSR germanium transistors that needs a new home and I'm trying new ways to use them since it gets a boring after while to just use them in Fuzz Faces and Buzzarounds. This one is a mix of ZVex Box of Rock and the biasing technique that RnFR (of Apocalypse Audio) is using in his designs that using germanium transistors.

Cap values is almost stock Box of Rock with three cascaded germanium boosters with the addition of a "Boost switch" which adds a 2,2nF cap in paralell with the 470pF/470K RC filter between the first and second gain stage.

I ended up with three MP21E transistors in the 60-70 Hfe range but other part numbers sounds great too, just be sure to use transistors with none to very low leakage.

It definetely sounds like a "Brown sound in a Box" pedal, a bit darker and it has a slight "Lo Fi nature" to it. And with the Boost switch on and the gain control dimed you get a really thick fuzz out of it.

[Pavlos]

looks good as always Anders
Missed opportunity with the name though, you could have called it Box Of Krautrock
Would have been a nice play on words for the 'parent' circuit and a homage to the rather underappreciated German bands such as Can, Neu etc.

[anders]

Haha,Box of KrautRock, we'll save that name for fitting circuit in the future.

[Pavlos]

glad you like it  I'm sure there are plenty more daft but somehow appropriate names floating around somewhere as well

[glasspak73]

Do you have a schematic for this? I plan on building a few.I also have alot of PNP germanium transistors some of them are the OC81 but hfe are low like 20 to 30.Thank you for this circuit looks like just the thing i been looking for.

[anders]

 I'll load up a schematic in a couple days. I just can't wrap my head around EAGLE but found CircuitLab. Need to learn it first but a schem is in the pipeline.

[PMowdes]

Anders, anytime you want an Eagle tutorial drop me a PM dude.  it's easy once you know how

[glasspak73]

Thank you Anders.I joined the curcuitlab site now i'm going to dive in and study.thank you for the link

[anders]

@PMowdes Wow, thanks, I'll defintely drop a line when I'm ready to tackle Eagle. I'm a bit curoius about designing PCB's and make circuit sims. Much appreciated.

Here is a first try on a schematic. It probably contains a few errors but it seems clear enough to read. I've left out the power switching and LED.

[HamishR]

This is such a cool idea!  I have wondered if it would be possible to make a BoR with regular BJTs because I have worked out that I don't like the sound of Mosfets.  Every dirt box I have ever made which has mosfets in it sounds harsh to me - even the OCD.  They always sound good at first but after a 1/2 hour or so the sound becomes extremely fatiguing.

I have built an OCD with BJTs as clippers and it sounded a lot smoother/less tiring on the ears but it was still an OCD...

The BoR is intrinsically a great sounding pedal.  I might have to try this with some of my Russian NPN Ges.