so after some much deliberation, some of us thought it would be good to have a thread about the sound of different Ge Diodes and Transistors. here's some of what i've come up with from my own experiences. by all means, add what you've found out, hear, suggest, etc. and ask whatever about these fantastic parts made from a great mojotastic/black magic element.
GT308V, but look for 1T308V (military version) - i've had not great luck with GT308V's most i've gotten are in the 50hfe range, while the military spec 1T308V's are mostly in the 70-90hfe at lest what i've got. they sound great, a little on the dark side, warm and fuzzy, great tone, great in the fuzzface. in fact i only took them out because i tried the GT402V's and just feel in love with those, but none the less great transistors. btw, nothing wrong with the normal GT308V's just mine have never seemed to be as good as others.
GT402V - hard to find, and can be expensive but sound AMAZING in a fuzzface, may be sacrilege to say, but sound very similar to my ears to my NOS Red Dot NKT275's, bright, not to bright, singing sustain, warm fuzzy goodness. side note: i find them to sound best with a bias voltage in the 5-6V range rather then the typical 4.5V.
GT108V - sound sorta like a cross between Ge and Si. they have their own vibe, but really great. a little more on the Si "harsh" vibe, rather then warm, but really lets you cut through the mix. i kinda think of them as if a Ge and Si mated, and you'd get the GT108V. if you see GT309G's or GT309's, they are supposedly the same, or at least sound very similar.
GT109V's - super high gain, i have some that have over 600hfe. they are teeny tiny, and like the GT108's & GT309's they sound sorta like Si to me, and a little noisy. i don't think anyone else has picked them up, or at least said anything about the, but they are usually super cheap so it would be worth picking them up and giving them a try.
MP20A - my #3 go to Ge. warm, well rounded in tone. work great in anything from rangemasters, and fuzzfaces. love these. great in anything. also look for MP20B's, these are higher gain versions, same tone more volume and sustain.
MP16B - just picked these up and some MP16A's. AVOID the MP16A's, they are low gain, despite the datasheet saying they should be up to 100hfe. i haven't tried these in a circuit yet, but the MP16B's are listed as a sub got 2n404's. good in fuzzfaces, i find these make a heavy, thick and gnarly fuzzface.
MP21D - great in tonebenders for Q1 & Q2, and great in fuzzfaces too. big and fat. the gain is usually lower then what they should be on the datasheet, but very usable.
MP41A - NOT MP41. wide gain spread, but sound big and fat. i have 2 with hfe in the 90's in my modified Oracle fuzz, which is based on a MK 1.5 tonebender, and it sounds thick, rich, and heavy.
NPN look for MP38A. they seem to have disappeared, but have almost no leakage and great gains, which is rare for NPN Ge's.
MP35's. i got some and the gains are pretty low, highest were in the 50's. i haven't tried them in anything, so i can't comment on their sound, but have been avoiding it since the gains are pretty low.
also, i know the the joe bonamassa fuzzface asks for MP39B's. i got some before that came out, but i can tell you most of them had gains in the 40's, so i'm not sure if the ones in the pedal have ones that are higher gain or if it should be that low.
also, i've had terrible luck with GT404's, which are NPN's. i their leakage was so bad i have some over 1uA. supposedly they sound fantastic, but you have to sorta a lot to get a few good ones, and they're expensive.
D310: have a nice, rich, warm distortion to them, close to some of the 1n34a, and mojotastic to look at. they help provide some nuclear power for your pedal
SFD-112: warm and smooth, can get a great fuzziness to them, but the circuit remains very clear, ie: you can here the individual notes while you play.
SFD-111: very similar to the SFD-112. the main difference is they seem to breakup a little earlier, and are a tad less clear. one of my top choices.
i have to find the time to write out a good description of all the others i have, including what i hear from the different D9's.
what i can say as of now i love the D9V's. i think that breakup beautifully and the harder you play the more they breakup, so it adds a lot of life to my playing. to me its like they just beg you to play harder and give it your all. and since they react to your playing, you can easily control the amount of clipping just by controlling your playing.