[sdiy] Direct Injection box?

[DCMagnuson at aol.com]

In a message dated 4/5/01 4:43:42 PM Eastern Daylight Time, 
paia2720 at hotmail.com writes:

> A direct box (for bass or guitar) usually converts from single
>  ended to balanced output, and provides attenuation to go into the
>  microphone input of a mix console. Isolation is usually a feature, as is 
the 
> 
>  ability to separate the grounds. Very often an audio transformer is 
>  involved.

Besides attenuation, direct boxes also provide impedence matching.  A guitar 
or bass needs to be connected to a very high impedence input to avoid loading 
the pickups.  The mic output is a fairly low impedence (usually around 600 
ohms)  

Dave Magnuson