[GLLUG] Audio Production

[James Roberts]

On 05/12/14 15:21, Chris Bell wrote:
>     As an aside, I am told that professional sound studios often prefer older
> sound hardware which uses germanium transistors which are low noise compared
> with silicon.

With apologies, and without personal aspersions - that's an... 
"interesting suggestion"... and I rather am of the opinion that it's a 
pseudo-audiophool urban legend (as in, 'pull the other leg-end').

That's speaking as a (once) professional recording studio designer (and 
speaker, amp, preamp, multi-track, test equipment etc. designer), and 
user of same - admittedly mostly of yore.

I grew up on germanium (which we sometimes called 'geranium' as in 
'flowers briefly') and one of the best things ever to happen to the 
semiconductor industry was the replacement of noisy, smelly ('cos they'd 
melted - again) and generally mayflower-like germanium devices with 
quiet robust silicon ones - especially when the planar process arrived. 
Old germanium devices as in early transistor equipment were dreadful - I 
still have drawers full of them, against the unlikely chance I can ever 
find a use for the junk.

I have nothing against germanium as a semiconductor - it has some 
merits. For example, a much lower forward junction voltage of 200mV 
against around 650 mV for silicon, so it's a good low-level rectifier - 
in a modern construction that is.

And silicon-germanium alloys are showing some very useful 
characteristics in modern use.

But if we are talking about old, point and junction contact germanium 
devices they would regularly go noisy after anyone even f**ted near 
them, let alone applied a (hot) soldering iron (bad idea - made 'em go 
noisy).

When working, their noise level was determined by the circuit design - 
as it should be, and not by the device - but there were no 
large-junction devices ever available in the past to make true low-noise 
low impedance low-level pre-amps, so transformers were always required 
for base impedance matching to get a reasonable noise level (always 
worse than that from valves, incidentally).

Please forgive me Chris for jumping on your comment, but I believe that 
whoever issued it originally was deeply misinformed and probably bereft 
of useful instrumentation.

There's a lot of it about.

An anecdote - it is Friday - once (in my 15 year studio career) I was 
invited round with a colleague mix engineer by one of the Hi-Fi gurus, 
who worked for a magazine that my newsagent insisted on calling 'Hi Fi 
Nudes'.

He had a pair of 'valve' (wow - had hoped we'd got rid of those) 
mono-bloc (sounds impressive - why not 'mono') Hi-Fi amplifiers one of 
which he had modified by removing the main negative feedback loop and 
adjusting the gains to compensate. This was a man who hated negative 
feedback and blamed it for all ills that he (though not me) could detect 
in almost anything.

I was known as a bit of a golden ears in the studio side, so he wanted 
the opinion of myself and the other mix engineer as to the much improved 
sound of the modified amp.

So he had one on the left, original, and one on the right, modified.

These were plugged in to a set of KEF speakers - very large ones we 
called the 'kangaroo'. They were the first hifi speakers to correct for 
speaker voice coil alignment  and were generally very good (but looked 
like kangaroos).

So he turned it all on.

After a few seconds of peaceful silence, it warmed up.

A loud 100 Hz hum came out of the right speaker.

'Ah - just wait while I put this on', he said, and went to his turntable 
and started to play - Steely Dan, I think it was (superb studio 
recording of the highest quality).

And out of the left speaker came Steely Dan. Out of the right speaker 
came 100HZ hum with cross-modulated and possibly even ring-modulated 
'Steely Dalek' with about 30% distortion and nothing above about 6 kHz - 
but lots of bass. Distorted, modulated bass.

'There!' he said, pointing to the right. 'Doesn't that sound better?'.

I cancelled my subscription the same day.

Nothing that has happened since has raised my opinion of audiophiles.

MeJ



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