What to do with low gain GE PNPs

[studiodunn]

I finally got around to going through my stash of 100+ germaniums and ended up with approx. 10 with 70+hfe. So now I'm brainstorming for something to do with probably 70 sub-50hfe transistors. I'm open to wild ideas so what says everyone?

[EBK]

If they are low enough in gain, consider connecting them as Darlington pairs.  Smallbear has a page discussing this.
http://diy.smallbearelec.com/HowTos/BreadboardRMs/BreadboardRMs.htm

[studiodunn]

If they are low enough in gain, consider connecting them as Darlington pairs.  Smallbear has a page discussing this.
http://diy.smallbearelec.com/HowTos/BreadboardRMs/BreadboardRMs.htm

Perfect! That's what I'm after - bootstrapping ideas.

I did get heartburn thinking about troubleshooting that build though.

[WormBoy]

There's no harm in trying them in a fuzz face ... (or other fuzzes). I played around a bit in the past with hfe around 50 for Q1 and around 20 for Q2, and got some very nice and useful overdriven sounds. Further, you can always use them as a Ge buffer stage or as Ge diodes ...

[matmosphere]

Don't they work okay until harmonic percolators too?

[Betty Wont]

Low gain Germaniums work well in Fuzz Factories too.

[studiodunn]

There's no harm in trying them in a fuzz face ... (or other fuzzes). I played around a bit in the past with hfe around 50 for Q1 and around 20 for Q2, and got some very nice and useful overdriven sounds. Further, you can always use them as a Ge buffer stage or as Ge diodes ...

Theres an idea..........they were cheaper than 1N34As

[Bret608]

If you have any in the 40 to 50 hfe range and they're low leakage as well, those are ideal for Q1 and Q2 in a MkIII Tonebender. They're basically working together in a Darlington configuration. If you have any beyond that which are above 70 hfe and leakier, there's your Q3. It's a forgiving fuzz to build and sounds better than most others in my opinion.

[studiodunn]

If you have any in the 40 to 50 hfe range and they're low leakage as well, those are ideal for Q1 and Q2 in a MkIII Tonebender. They're basically working together in a Darlington configuration. If you have any beyond that which are above 70 hfe and leakier, there's your Q3. It's a forgiving fuzz to build and sounds better than most others in my opinion.

Does the leakeage add up in Darlington configurations?

I'm currently doing all of this GE learning on a pastyface build.

[danfrank]

Anything with gains in the 40s will make nice sounding rangemasters. I haven't tried anything below 40 though.
My other idea was mentioned above... Darlington pairs. If you have any really low gain NPN germaniums (hfe 10-20) you can make sziki pairs, mentioned in the above small bear link. Yes, I totally spelled that wrong!

[Bret608]

I'm not sure if the leakage adds up, but once I read that for the MkIII Q1 and 2, you should put whichever is lower leakage first. So I did that in the two I've built and have had good results. Honestly though I've never tried any with higher leakage than 0.060mA, so I don't know how much it really matters. The main thing is to make sure Q1 and 2's cumulative hfe is about the same or not much higher than your Q3 hfe--that will keep the fuzz from being too muddy and overcompressed. Also, since you're doing a Pastyface, keep in mind that the bias trimmer on Q3 is really just simulating leakage and is not a voltage starve or something like that. That's most likely because Fuller was using Q3 transistors with more or less no leakage, which the circuit doesn't really like. Use your ear of course, but look for Q3 collector voltages of about 2 to 2.5v. More than 3v still sounds good but gets a bit raspy in my experience. You can go down to 1.5 and it sounds good too, but may be a bit more smooth and tame than you'd like.

[studiodunn]

I'm not sure if the leakage adds up, but once I read that for the MkIII Q1 and 2, you should put whichever is lower leakage first. So I did that in the two I've built and have had good results. Honestly though I've never tried any with higher leakage than 0.060mA, so I don't know how much it really matters. The main thing is to make sure Q1 and 2's cumulative hfe is about the same or not much higher than your Q3 hfe--that will keep the fuzz from being too muddy and overcompressed. Also, since you're doing a Pastyface, keep in mind that the bias trimmer on Q3 is really just simulating leakage and is not a voltage starve or something like that. That's most likely because Fuller was using Q3 transistors with more or less no leakage, which the circuit doesn't really like. Use your ear of course, but look for Q3 collector voltages of about 2 to 2.5v. More than 3v still sounds good but gets a bit raspy in my experience. You can go down to 1.5 and it sounds good too, but may be a bit more smooth and tame than you'd like.

Thanks! That explained allot about the pastyface in particular. i was curious why I was only getting a max of 3v on Q3, as that was well under the 4.5v in the docs I've read. Ultimately I do everything by ear and just plug and play until I can't stop playing fumanchu riffs.

[Bret608]

Cool! Glad it was helpful. It's funny you mentioned Fumanchu. It was their bassist Brad Davis (aka Creepy Fingers) whose posts on MkIII gains, etc. over at the DAM forum were helpful when I first built one of these.