Many audiophiles told me that germanium "sounds" better than silicium, and this is the reason they prefer vintage amplifiers over more modern devices that adopt silicium.
Yes, I know that germanium was the first substate available for BJTs, and that the introduction of silicium happened only years later.
Nonetheless, purists still claim that germanium is better. Indeed there is a niche market for the vintage BJTs, similar to that of vacuum tubes.
From an electronic point of view, surely there are differences, yet I don't see how they can influence the quality of sound.
So, I wonder if this preference for germanium is based on an urban legend, or if there is really something scientific, something that I can measure with an adequate instrumentation?
I think is more likely an urban legend but there it should be something of true. The germanium has a B-E voltage of 0.2 v (about), while the silicium has 0.6 V. So the silicium transistors have a greater crossover distortion (zero crossing). Increasing the rest current the problem is solved, also with silicium, but it is well known the problem of A-Class working! And remember that germanium transistors must work at lower temperature. At low powers, with germanium, with low rest current, perhaps they work more closely to A-Class but.... I'm not sure. I remember, '60 years, my germanium first amplifier, Geloso, 10+10 W, with output transformers, like tubes: the sound was nice, but the noise was greater.
I followed a PHd student, studying the electric guitar amplification, in anechoic room, Bruel & Kjaer microphones and spectrum analyser. Same guitar, same lodspeaaker. The transistor had a lower distortion, but with odd harmonics, the opposite with tubes (greater distortion but with even harmonics. Should be interesting to analyse in the same manner this problem, Ge vs Si!
Grazie Andrea :-)
yes, what you write is most logical. I didn't remember the different Vbe drop of Germanium, this may explains some differences in certain configurations.
But if your amplifier is far from distortion, the sound should be very similar - if not equal.
Of course vacuum tubes behave better when distorting, but BJTs work at much lower voltages - and this is a big advantage from many points of view (for example the CE certification!)
Your guess is right: the preference for germanium can be regarded as this urban legend. Many audiophiles have a strong (almost religious) belief that germanium is better than silicium, tubes are better than semiconductors, etc. As has been said already, the BE voltage of germanium transistors is about 0.2 to 0.3 Volts whereas that of silicium is about 0.6 to 0.7 Volts. But that has not much to do with the cross over distortion of a power stage with transistors. What is crucial to this cross over distortion is the equality of the two halves of the power stage. Ironically, with silicium transistors it is much easier to reach a high level of equality compared with germanium. In addition, (as said already) silicium can stand a much higher temperature range so that cooling requires less precautions.
In modern power output stages dual complementary power mosfets are used which have almost exactly the same (complementary) properties and a smooth I/V characteristic. So in practice the problem of cross over doesn't exist anymore. Additionally, these mosfets can be made for high voltages and currents so that output stages for very high power and extremely low distortion (say, 0.01% for the full power range!) can be made quite easily.
For pre-amps the noise properties are important. Here germanium is greatly inferior to silicium. So no need for germanium in the audio field at all.
For tubes versus semi conductors the story is even more dramatic for a number of reasons. About the aspect of distortion: in case of semi conductors, when the power stage is driven too high, the signal clips abruptly, causing high odd-harmonics-distortion. Vacuum tubes produce a gradual increasing distortion, starting already far below maximum amplitude with high values. Easy to prefer semi conductors then I suppose.
there are plenty of reasons why silicon is far better, including better temperature range and therefore far better for power circuits (like audio amps), far easier to build both NPN and PNP devices allowing for symmetric bipolar circuits (balanced circuits handling both phases of audio signals), and less noise (germanium transistors tend to be noisier), and higher voltage breakdown limits.
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