germanium vs. silicon

Non-Rickenbacker Guitars & Effects

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germanium vs. silicon

Postby (Tube_Fan) » Fri Dec 08, 2017 4:05 pm

Some interesting information on transistors.

Germanium Can Take Transistors Where Silicon Can’t
https://spectrum.ieee.org/semiconductor ... licon-cant

Giuseppe Scarpi
Why is germanium considered better than silicium for audio applications?
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?
https://www.researchgate.net/post/Why_i ... plications

Tubes vs. transistors & quantization distortion
http://audiokarma.org/forums/index.php? ... ion.327777
(ignore the skeptics on this forum, they didn't read the references and most don't know physics and chemistry)

Some bad links can be found here
https://web.archive.org/web/20100203045 ... tions.html

https://web.archive.org/web/20130529083 ... ortion.pdf
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Re: germanium vs. silicon

Postby (jps) » Fri Dec 08, 2017 6:41 pm

Tube_Fan wrote:...From an electronic point of view, surely there are differences, yet I don't see how they can influence the quality of sound...

They influence sound just like most anything else in the signal path. Why do various 12AX7s sound different, for example? Should all of them with the same basic specs sound the same? :wink:
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Re: germanium vs. silicon

Postby (Tube_Fan) » Fri Dec 08, 2017 7:16 pm

Here's references 13 and 14 listed in Hawksford's article.
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Re: germanium vs. silicon

Postby (Tube_Fan) » Fri Dec 08, 2017 7:18 pm

Some comments on Hawksford's article and two pages about traps in semiconductor materials.
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Re: germanium vs. silicon

Postby (Jubal81) » Mon Dec 11, 2017 5:58 am

Interesting stuff. Thanks for the links. Pretty much nails what I've run into and been trying to work around.

I love the way germanium clips/distorts guitar signal, but I've found it's too noisy for my taste for amplification stages. Spent almost a year working on a pedal preamp that uses low-noise/high-current JFETs for amplification with multiple stages of germanium diodes for clipping. I followed that with a very flexible tone stack. Basically trying to get the benefits of both.

Really digging it. Breaks up perfectly with no nasty 'ripping' distortion and noise is low enough you can hardly tell it's on even with the gain cranked up. Unfortunately germanium components are getting much more scarce in the past few years. I'm following a company called nanolog that uses 'molecular junctions' for clipping a guitar signal. Sound clips sound just like germanium to my ears. Only problem is the cost right now - about $35 for just one.

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Re: germanium vs. silicon

Postby (Tube_Fan) » Mon Dec 11, 2017 8:10 pm

Hardly scientific or objective, but whereas transistors operate on an invisibly microscopic, quantum scale, tubes exist and operate on an intuitive, human scale. You can see the heaters lit up, you can sometimes see a glowing plasma, and you can feel and hear the warmth. Everything about tubes exists in a more human realm than hard, cold transistors. Measure away, but it’s the sound that matters.


http://www.effectrode.com/signal-tubes/ ... -compared/
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Re: germanium vs. silicon

Postby (Tube_Fan) » Wed Mar 14, 2018 12:11 pm

One time I had an idea that you might be able to make a bipolar transistor out of both germanium and silicon and thought that if one element was slightly more n or p than the other element you wouldn't need to dope the elements. I found out later that these transistors exist and there are patent subclasses on them such as 257/183 and 257/197.

https://www.uspto.gov/web/patents/class ... hed257.htm

Also see https://thesis.library.caltech.edu/2531 ... _final.PDF


Here's and example with an integrated circuit.

US 3905037 Integrated circuit components in insulated islands of integrated semiconductor materials in a single substrate
germanium islands in silicon substrate
https://patents.google.com/patent/US3905037
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Re: germanium vs. silicon

Postby (Tube_Fan) » Sat Mar 24, 2018 4:09 pm

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Re: germanium vs. silicon

Postby (Tube_Fan) » Tue Mar 27, 2018 6:36 pm

I found two patents that show tubes at the input before a transistor stage. I was thinking that this might work to reduce noise for noisy transistors like early germanium transistors for use in fuzz boxes or other effects. Years ago I tried substituting the transistors in a wah wah pedal with some low noise silicon transistors and germanium transistors. The wah wah pedal was noisy with two germanium transistors in it so I put in a low noise silicon transistor as the first transistor and a germanium transistor as the second transistor (both transistors are NPN).

US 3308232 Magnetic recording and reproducing device
cascode triodes before transistors fig. 6
https://patents.google.com/patent/US3308232

US 3328711 Infinite plate load impedance amplifier
tubes before transistors
https://patents.google.com/patent/US3328711
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