OC72 transistors. What to build?

[digi2t]

I scored four OC72 transistors on EBay the other day, with a winning bid of $4. I just took a chance, I mean four bux, no big whoop if their junk, right? Two pairs, still in the original Mullard wax paper packaging. My Peak meter gives me the following gains and leakage numbers;

97 - 0.08mA
100 - 0.10mA
85 - 0.17mA
103 - 0.17mA

From what I can tell, they look like pretty sweet numbers. So... what to build with them? Feel free to chirp in here folks (that means you Lucifer's Trip). I know Tonebender springs to my mind, but are there any four transistor fuzz circuits that I could look at? I'd hate to be stuck with one tranny. Or maybe a dual fuzz circuit, that I could switch either parallel, or series?

Ideas?

[LucifersTrip]

Man, you just have the classic gains & leakages for a Fuzz Face / variant or Rangemaster. You probably need some more leakage for a Tone Bender in at least one of the trans.

You can use up three for a Buzzaround or TB MKIII or MKIV, but you can make them with less valuable low gainers for Q1/Q2 and again probably need more leak for Q3.

How about attempting an all germanium Big Muff....you can knock off all four....or do what you suggested, take two two-tran fuzzes and parallel and/or series them....one Fuzz Face and one Fuzz Rite. I don't think that was done many times.

[digi2t]

Ooooooo... germanium BMP! Damn, I hadn`t thought of that one. Considering that I`ve always loved that BMP roar, it might be nice to build one with a twist. Quite truthfully, I`m less keen on a dual fuzz since I built my Gemini III clone. I`m extremely pleased with it, and I don`t want to be redundant. I four banger would be more interesting.

Would you have any schematics that you could point me to? Something that my breadboard can chew into?

[digi2t]

Hmmm, came across this in my lunchtime internet travels;



How does that grab ya Luce?

Still searching for a Germ BMP style circuit....

[LucifersTrip]

I was going to suggest you just improvise your own 4 stage fuzz. Above looks cool...like the FZ-1 / MK1, it's linear stages, but the unique thing is the pot on the diodes and a boost. ...and just like those (FZ-1 / MK1), it'll be tough to duplicate results (or know what the inventor was going for) if you don't have voltages or at least a sound clip.

I was always considering a ge bmp, but I never got around to it (it must need rebiasing / tweaking). Most say that it won't be that different because of the high gain/clipping it uses...similarly, there's supposedly not much difference with a large range of hfe si transistors, though I noticed a significant difference with the Triangle I built with all transistors < 100 hfe.

[midwayfair]

I was going to suggest you just improvise your own 4 stage fuzz. Above looks cool...like the FZ-1 / MK1, it's linear stages, but the unique thing is the pot on the diodes and a boost. ...and just like those (FZ-1 / MK1), it'll be tough to duplicate results (or know what the inventor was going for) if you don't have voltages or at least a sound clip.

I was always considering a ge bmp, but I never got around to it (it must need rebiasing / tweaking). Most say that it won't be that different because of the high gain/clipping it uses...similarly, there's supposedly not much difference with a large range of hfe si transistors, though I noticed a significant difference with the Triangle I built with all transistors < 100 hfe.

Ge works fine, but lower gain. Decay will be a little gated. Grounding the emitters would probably help. Removing or reducing the 470pF caps might help. Removing the clipping diodes from q2 might help push q3 hard enough to still get good sustain. I'd also gain up q1 some.

Check out the EQD Hoof fuzz for an example of a germanium hybrid muff.