Thanks for the info. I have a reasonable selection of old Ge transistors so I’ll look in there for some AF379s. Perhaps the MC head amp with germaniums could be a reality after all. Do you have to hand the rbb for it?
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I have low noise GE transistor P28 (П28) for RIAA corrector and correct Spice model for this transistor. I have 22 simulate circuits in MultiSim 14.0 with this transistor for RIAA corrector.
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The sound of germanium transistors is much closer to a tube sound, than silicon transistors.
There is "Warm tube sound".
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Good that you’re fiddling with germaniums. On the nfb designs the input impedance varies with frequency, and on some of the circuits the input impedance is also very low, difficult for a MM cartridge to drive without rolling off in the top end.
Have you tried using them in a headphone amp circuit?
Have you tried using them in a headphone amp circuit?
Not quite germanium. But still.
Германиевый усилитель для наушников. (разработка) - Страница 3 - Форум
Was more successful schemes germanium fono . For example Shure M-61, or Telefunken TV-206 . The supply voltage of 30 to 32 volts . I was made 2 devices on these schemes . Sound very good .I use them for several years .Vinyl Engine -Germanium phono preamp (5) , Vinyl Engine -Germanium phono preamp (3) , Vinyl Engine -Germanium phono preamp (7) , Vinyl Engine -Germanium phono preamp (8)
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The early Ge parts were horribly hissy. We were still getting them into the 1970s in low-low-cost gear.
The Russians made a LOT of Ge devices after the rest of the world had the fad for Silicon. I hear reports that some of the Russian devices were quite low noise. Russian Ge is readily available as new Russia cleans-out the USSR military back-inventory. Which ones are "quiet" I have no idea.
Aside from the passivation techniques found for Silicon, it was the custom to pot Ge with greases or solvents (benzene) to reduce surface states as well as improve cooling.
The Russians made a LOT of Ge devices after the rest of the world had the fad for Silicon. I hear reports that some of the Russian devices were quite low noise. Russian Ge is readily available as new Russia cleans-out the USSR military back-inventory. Which ones are "quiet" I have no idea.
Aside from the passivation techniques found for Silicon, it was the custom to pot Ge with greases or solvents (benzene) to reduce surface states as well as improve cooling.
Some of us actually want a transparent amp that doesn't pollute the signal with "warmth" or any other woolly adjective! Uncorrupted signals please. The idea of using low performance Ge transistors is unappealing except perhaps from a retro perspective - sure its a design challenge, but its not going to be the best way...
The original comment about low noise of the AF379 completely ignores the flicker-noise knee frequency - 600MHz capable RF transistors' noise specs seldom give this, and typically noise increases with decreasing frequency, sometimes dramatically, you cannot infer audio noise performance from RF noise performance - you'd have to measure it rather than extrapolate from 100MHz data.
The original comment about low noise of the AF379 completely ignores the flicker-noise knee frequency - 600MHz capable RF transistors' noise specs seldom give this, and typically noise increases with decreasing frequency, sometimes dramatically, you cannot infer audio noise performance from RF noise performance - you'd have to measure it rather than extrapolate from 100MHz data.
Do you assume the preamp under discussion has such flavour? Why? Harmonic spectrum? Noise? Are either of these really excessive?
A "transparent amp" is an unattainable ideal, real amps are all about trade offs and compromise.
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