Author Topic: Germ Transistors and correct leakage ranges  (Read 97 times)

TySN_Sound

Germ Transistors and correct leakage ranges
« on: May 22, 2020, 10:19:54 PM »
Hello all,

I recently got a small batch of germ transistors, measured them, and like normal there are some that have a leakage that is considered too high (4-600) for a typical range/fuzz application.
Out of curiosity I tried some of the high leakage ones in a rangemaster build, comparing them to low leakage ones (50-150) in a similar gain range.
Now, I've never played an original (range/fuzzface/bender) and I'm still pretty new to the circuit(s) and the whole germanium experience.
But from what I've read these leaky transistors should be noisy and overall not sound right or good, however I thought they sounded GREAT!
The noise floor overall was similar, maybe slightly higher, but nothing that would make me second guess it. The tone was very similar (hard to say if it's the leakiness or different types of transistors, and I didn't have matching pairs of the same type with hi/lo leakage).
I've only tried it today, so as far as how stable it is has to be fully tested, but even with me holding the transistor in my hand for a minute vs letting it sit at room temp for 20 minutes did little to change the sound.

This experience has completely confused me in term of what leakages are considered bad.
I can see how in a multi transistor circuit with different gain stages could magnify any problems, but for the rangemaster I don't see any problems.

I am curious if this is a case of "all transistors will act a little different" and these leaky ones just happen to work in the circuit, or if I'm missing something.
« Last Edit: May 22, 2020, 10:25:29 PM by TySN_Sound »

Re: Germ Transistors and correct leakage ranges
« Reply #1 on: May 23, 2020, 06:19:48 AM »
Some types leak more than others. That is to be expected.

The circuits are usually biased for a certain leakage and gain range, but there can be a wide tolerance in which it works well. Just drop 'em in and see how they bias and what they sound like. Measuring hfe and leakage only makes tweaking the tone easier because it gives you control.

The Rangemaster was designed with a low leakage type (OC44) in mind, but as you can see it still works well with plenty of leakage.