Germanium Transistors, All Hype Or Worth It?

They are not dull in any respect should you surround them with trendy passive elements and so they’re certainly not heat or any completely different sounding than a silicon transistor if you happen to choose the right circuit for them.You may even find some advantages over silicon transistors in area of interest areas . Moreover there are tons of very totally different germanium transistors outhere and they do not behave all the identical nor have the identical parameters so that you need cautious selection and even simulations if models can be found for your specific design.

The only downside of germanium transistors in a preamp is noise and current leakage.Current leakage may be minimised with pnp transistors equipped at decrease voltages.Making the bias base resistor as excessive as doable on your circuit additionally work, however present noise needs to be taken into account so search for good compromise .60’s phono preamps prefferably used a silicon transistor for the input stage as a consequence of noise issue.

At line and headphones level they’re supreme and their sound is not dull at all.You’ll be able to apply any distortion reduction method employed with silicon transistors and it’ll work very properly.I did it in my headphones amp and i couldn’t make a distinction between tpa6120 and my germanium amp on 250 ohms bayerdynamic dt880 headphones.Possibly I am deaf….

When entering into high energy area you have to take current drift on account of temperature under consideration and discover the correct compensation.Additionally consider the max voltage and heat dissipation cause germanium isn’t too nice in that redpect nor you’ll be able to easily find excessive energy complementary transistors if at all… .Complementary phases with Ac 180/81/87/88 are prefferable to transformer driven solution solely if you have sufficient transistors to make good pairs.Larger power transistors with good FT are exhausting to search out or expensive.

Don’t believe anybody till you get to experiment yourself with them as a result of they don’t behave like silicon transistors and remember, you may try any diabolicaly difficult schematic you may consider. By the way in which , ac187/ac188 have been reported to have pretty low voltage noise to allow them to present good SNR with low input impedance sources like DAC outputs.Among the features of germanium transistors have been by no means explored by our modern requirements or the knowledge is difficult to search out in some instances.

No one ever thought of for example an i/v converter based on germanium transistors after a DAC as there was no audio DAC in the 50’s or 60’s or 70’s so many issues will be tried.

The low FT of germanium kaufen transistors argument that people often convey into discussion is unsuitable with emitter followers and low achieve common emitter levels and you’ll find that by yourself as they haven’t got the same effect as gm doubling has in silicon transistors.Due to the lower BE voltage needed to open the transistor a zero.5 ohm emitter resistor used with germanium transistors could have 2…Four occasions larger distortion discount impact that the identical zero.5 ohms resistor has with silicon transistors depending on how excessive the collector current is.Moreover you may aplso use PTC resistors as emitter resistors to insure thermal runaway compensation too instead of the classical NTC resistor positioned in the base bias circuit.

This doubling gm impact in germanium trz is also milder , has less agressive slope and that makes germanium transistors extra appropriate for class B amplifiers which can naturally current decrease current drift with temperature .Accompanied by modern op-amps their crossover distortions are theoretically much decrease than in their silicon counterparts, but their inherent higher junction capacitance ask for extra current drive yet that isn’t true with all transistors.Think about AC187/188 having max hfe=500 at 300mA while 1000mA is feasible to get out of them with the best heatsink.You will not find easily transistors with such excessive hfe at these currents in silicon transistors.That generally is a downside too in some applications, but usually i encourage anybody to assume extra about the use of germanium transistors in modern circuits even using simullators where it is possible.

You can even use superdiode circuits much like these utilized in silicon circuits for thermal compensation, however you must be sure that they can have superb thermal coupling with the final stage transistors because thermal runaway in germanium transistors is rather a lot faster than it is in silicon transistors so huge liquid or freon cooled heatsinks are better for high power germanium trz .You find them a lot in scraped computer cooling programs anyway.

They even have a really big advantage that others talked about too: they will work even with zero.2 volts over CE junctions in some instances so battery provided circuits can work very nicely with only one 1.2v battery whereas their CB and CE leakage current additionally drops with applied CE voltage so battery drain is healthier with lower voltages.