Breadboarding Germanium Big Muff Pi

[duck_arse]

too late for trying now, all soldered parts. I listened to each transistor before "selecting", nothing really struck me as too hissy. the smd transistors will pose their own problems, I'm sure.

the big white thing against the wall, with what looks like copper coming out, looks like wot jack white might have for his burst box. please don't let my carp typing expand yr vocab, and I shouldn't really poke slow at you, I realise you have other proper things on the go.

[Gus]

Just looked at this thread

If you are using Ge diodes for clipping I would try three Si transistors for another adjustment

Two diode clipping at stage two

Four diode clipping at stage three. Two one way and two the other.  This will increase the third stage level about the same as two Si diodes and you would still have some of the 2nd stage two Ge diode compression

Ge transistor at stage four

[digi2t]

Finally got mine together. I decided to go with 2N5087's at the front and back door, and all germanium in the clipping sections. The silicon cuts down on noise, while the 2SB176's lend a much more "organic" feel to this venerable circuit. 1N695 diodes for the clipping, all carbon comp resistors for that vintage mojo, and the values are my fav blend of triangle, ram's head, and russian circuits blend that seems to ring best to my ears. I find of all the BMP's I've built to date, this one cleans up best when I roll the guitar volume down. Not totally clean, but like a gentle overdrive that helps each note ring out a bit better. I ended up passing on the boost. I tried it, on both clipping sections, and although it did give me a great volume boost, it just killed the overall great tone.







I've been noodling with it for the past hour, and I've also been running it into Strategy's Holmes H-X6 Spectrum, and the tones coming out of this combo are just killer. It addictive. I'll try to get a video out tomorrow, I'm having too much fun with this right now.  

[smallbearelec]

I'm glad that I saw this thread. I have a lot of high-gain, relatively low-leakage PNP and NPN that are remainders from sorting for FFs and TBs, and I had a silicon BMP on the breadboard for other reasons. So I subbed a bunch of both flavors and I notice that it's very easy to line them up. I just stuck a trimpot in place of the usual 100K base-to-ground resistor and tweaked for 3.5 to 4.5 volts on the Collector. The circuit accommodates a pretty wide range of gains.

I have posted unaudited stock that's tested for gain and leakage and priced to encourage experimenting; some builders might like a mixture of silicon "dots" and Ge, and that's now possible pretty economically.

Regards
SD

[mac]

... and the tones coming out of this combo are just killer. It addictive. I'll try to get a video out tomorrow, I'm having too much fun with this right now.  Grin

Glad you like it

Note that this diode trick can be used in lots of circuit. As a matter of fact, I used it on a Jordan Bosstone first, then in a BMP. The Bosstone adaptation is in my gallery but you have to add the extra diodes. In a BMP it is as simple as replacing the emiter resistor for a silicon diode, so you can use online PCBs.

I ran a spice simulation long ago to see the resistance of the diode across the guitar freq range using my Germanium transistor model. It is about 136 ohm.



I'll run another sims to see the effects of the diodes when the current is high enough to reach its maximun forward drop.

mac