MP25A russian PNP transistor.

[Thecomedian]

I was able to get ahold of 40 of these, and each one has normal markings of written letters and numbers, but then there is an embed of a 2 or a 4 on top of the can. Are these numbers significant of anything?

[pinkjimiphoton]

maybe to the guys that made 'em.

all you need is pinout, and hfe testing. i've had real good luck with nos military russian ge's myself. love 'em!!

[Thecomedian]

Wow. I'm so appreciative of having these things. The 2n2222 Si NPNs from 80's radio shack produced so much excess "hiss", just turning from low to moderate volume for the perfboard fuzz face. Dunno if it was a design fault in my build or what, but these are producing VERY low hiss, pretty much equal to how much comes out of my bass naturally. The distortion itself sounds more mellow and pulsating. I just built it with parts I had to hand, so .47 tantalum caps and 47u electrolytic from ground to 1k pot.

The odd thing is I wasn't getting any distortion out of it to start, so I raised the varistor on the C of Q2 to 14k, and the thing only distorts with my bass at full volume.

[pinkjimiphoton]

you can usually nuke the hiss some with a couple well-placed small caps...100p to (really worst case) maybe 10n will work...if playing bass, you should be able to get rid of all of it pretty much, basses don't put out a lot over about 6k or so if memory serves.