[LAU] Line noise

[Fons Adriaensen]

On Sun, Oct 28, 2007 at 06:45:54PM +0100, leslie.polzer at gmx.net wrote:

> > You cannot do that in a sane way - the output of a guitar pickup needs to be 
> > modified (amplified and converted to high impedance) before, otherwise the 
> > signal will suffer (treble loss).
> 
> I believe you, but I'd be grateful if someone could explain to me how
> one would know that the treble will suffer? I mean, we were talking
> about real impedancies, and to determine how the line will react with
> respect to certain frequencies we would need the complex part...

The impedance of a guitar PU is mostly inductive, i.e. it rises
with frequency. So if you load this with a low impedance the
effect is that of a low-pass filter. That's the simplest case -
in practice the inductance can resonate within the audio band
when connected to a cable (which is capacitive) and this is why
guitar cables can have a distinctive sound. 

Anyway, for a guitar you need a high-impedance input, not a 
microphone input.

Ciao,

-- 
FA

Laboratorio di Acustica ed Elettroacustica
Parma, Italia

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