[LAU] Preamp for mic/ guitar (was: hardware: recording voice and acc. guitar)

[Fons Adriaensen]

On Fri, May 30, 2008 at 09:24:32PM +0200, Arnold Krille wrote:

> I don't really think this is a problem. Afaik the phantom-power-spec is to 
> provide something between 9 and 52 volts. 48V is only a common usage.
> Unless I am prooven wrong...

Many mics expect around 48V in series with two resistors
somewhere between 5 and 10k (or half this value if the
voltage is delivered to the center tap of an input
transformer).

The (AFAIK) unofficial spec is 45-50 volts unloaded, and
being able to deliver at least 5 mA (some would say 10 mA)
which roughly corresponds to the resister values given above.

It is absolutely NOT normal that the voltage delivered to
one mic depends on the presence of others. It must not
drop even if all other lines are shorted to ground.

Ciao,

-- 
FA

Laboratorio di Acustica ed Elettroacustica
Parma, Italia

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