[sdiy] Direct Injection box?

[Happy Harry]

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.

Non Isolated units can be built with opamps...

I'm running a synth from my Theremin. I have a PV-1 pitch to voltage
converter that thracks the theremin audio out (before the volume circuit) 
and drives a synth VCO directly (1V / octave). Its much more
fun to play than a theremin....

H^) harry

(shameless plug... the PV-1 board is available from EFM... I designed it 
based on the Etherwave Pitch to Voltage converter by Bob Moog... used with 
permission.)





>From: "Jon Darby" <jdarby at lplizard.com>
>To: <synth-diy at node12b53.a2000.nl>
>Subject: [sdiy] Direct Injection box?
>Date: Tue, 10 Apr 2001 12:57:22 -0400
>
>Howdy, everyone,
>     What exactly, from an electron's point of view, is a Direct In box? 
>I've had to play through a few as a bass player in some shows, mainly where 
>some professional sound guy named "Smokestack" Jenkins has been hired to do 
>the sound. I've never questioned what it was. Does it just split the signal 
>and boost the outgoing signals to make up for any loss in the split 
>process? What amplifier did the other output go to that required this 
>beast? Do some PA systems run inputs at line level? The reason I ask is I 
>was curious about sending my Theremin's audio out through my Moog Rogue's 
>Audio In to see if I want to clone its filter to add to my Theremins, and 
>apparently it requires a hotter signal to pass the audio through. What 
>parts are involved in building one? It couldn't possibly be more than a 
>slight amplification of the input audio, could it? Could a simple 
>transistor amplifier circuit suffice? Are there any public schematics 
>available? THank you for entertaining this wordy request!
>
>Your pal,
>Jon Darby

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