I bought 50 MP38A transistors and tested them for gain and leakage. These NOS Russian transistors manufactured in the 80's. They were in a plastic bag that had never been opened. Here are the results:
According to the specs the Hfe range is 45-100. The vast majority of them are in the 50's and 60's. There was one that measured 92, none in the 80s, and a probably about 5 or so in the 70's.
Most of them had very low leakage. Only 2 of them had leakage around 500uA and one had a leakage of 1000uA. There were a few that were right around 300uA. Everything else was really low. I didn't make note of the exact figures for leakage because they were (almost) all so low. 2 of the 3 leaky ones had gains down in the 30's, which I thought was odd, because everything I read would indicate higher gain transistors are more prone to leakage.
Before I measured them I tried 2 random ones in a fuzzface that had silicon transistors socketed. They sound fantastic in the that pedal. When I measured the 2 that I had tried in that fuzz, they were 62 in Q1 and 74 in Q2. Those are lower than the "sweet spot" that people usually mention for the fuzzface, but they sound great to me.
I spent some time today trying various combinations of gains in the same pedal and to me, it's not really what I would call a night and day difference. It's more like slight variations on the same theme. Granted, the Hfe's range from the high 40's to the low 90's and I only played each combo for a few minutes, so the results those results aren't exactly conclusive.
I've very pleased with the results. I'd like to see some higher gains, but with only 3 duds in the bunch, I can't complain. I can find plenty things to do with 47 good germanium transistors.
This is my first time using germanium transistors, but now I get what all the fuss (fuzz) is about. These low gain germs sound wonderful. Even when I tried 2 transistors with hfe's in the low 50's it sounded great to me. It sounds like everything I have ever read about germs in a fuzz face. I want to compare them to some 2n2369's that I have in the same gain range, but that's for another day.
2 things to be aware of if you are going to try these:
1: the base is connected to the metal casing, so make sure it isn't touching anything
2: the casing on these is 2-3 times the size of your typical T05 style case (photo attached)