[LAU] OT: Guitar level- Mic or Line?

[Fons Adriaensen]

On Thu, May 29, 2008 at 09:39:36AM +0200, Andre Majorel wrote:

> 
>                               ^ +15 V
>                               |
>                          -----------
>                         |   _ |     |
>                         | 2| -_7    |
>                          --|-  -_6  |   220
>                            |    _---+--^v^v------\  /|  TO
>      FROM  |\  /-------+---|+ _- TL071            \/ |  LINE
>    GUITAR  | \/        |  3|_-|4              _______|  INPUT
>   OR BASS  |_______    <      |              |
>                    |   > 1~5M |             ---
>                   ---  <      v -15 V
>                        |
>                       ---
> 
> You could surely do something similar with a unipolar supply (9 V
> battery or wall wart) but I don't know how. There is probably a
> bipolar supply inside your mixer, though. If it doesn't exceed
> +/-18 V, you could use that. Shouldn't be a problem, a TL071 draws
> very little current.

Two 9V batteries should be fine. I'd add some 0.1uF caps 
between the power supplies and ground, mounted as close as
possible to the chip. Also one in series with the input.

There are other chips you could use, even double or quad
opamps such as the LM series from Texas.

Ciao,

-- 
FA

Laboratorio di Acustica ed Elettroacustica
Parma, Italia

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