DX7 controls.

[The Old Crow]

On Fri, 10 Oct 1997, bj wrote:

> The Old Crow wrote:
> 
> >   Back in 1986, I built an outboard system that provided a realtime knob
> > or switch for every DX7 parameter.  The device was rather large (it was
> 
> Did you have a separate MCU/CPU for the scanning if the pots?
> Or did you make the pot scan from a PC?

  Each module had it's own microcontroller, in this case a Zilog Z8.  The
uP operated a discrete integrating A/D that sampled at around 48Hz, with
the result scanning the knobs around 3-4 times per second.  I went with a
discrete A/D (which is rather easy to do, since most of the A/D is
actually software) because it was the most accurate at the sample rate I
was using.  (That, and my experience with it was good, having used it on
the front end of many process control instruments).

  I should note that each switch or knob had its own LED or LED display
for feedback.  One could actually sit down and program a patch (given that
one had a good idea of the FM synthesis model and what to expect without
actually hearing anything) without the need of the synth itself.

  --Scott

/*------------------------------------------------------------------------
   Christopher S. Rider -- "The Old Crow" -- http://www.mcs.com/~syzygy/

          God's in his Heaven.  All's right with the world.
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