[sdiy] Tau Systems

[Juergen Haible]

AFAIK pnps of the same size are less noisy than npns.
Maybe due to the different mobility of electrones vs holes?
It's been a long time since I've learned (and then forgotten) that ...

JH.


----- Original Message ----- 
From: "Stewart Pye" <stewpye at optusnet.com.au>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, March 30, 2011 11:02 PM
Subject: Re: [sdiy] Tau Systems


> Usually the transistors in discrete microphone preamp designs are PNP too. 
> I've always assumed this was because it was easier / cheaper to get low 
> noise PNP transistors. Even modern discrete designs use PNP transistors. I 
> left my copy of "Small Signal Audio Design" at work. It may shed some 
> light on this...
>
> Regards,
> Stewart.
>
> lanterma at ece.gatech.edu wrote:
>> On Mar 30, 2011, at 1:51 PM, <jays at aracnet.com>
>>  <jays at aracnet.com> wrote:
>>
>>
>>> In the day of Japanese radios most of the transistors used were
>>> germanium and not silicon. PNP germanium transistors were easier to
>>> build and I think may of been less noisy than NPN ones.
>>>
>>
>> PNPs also seem to be used all over old guitar pedals (like the original 
>> Fuzz Face), probably for the same reasons.
>>
>> - Aron
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