Analogue Computer knowhow?

[Grant Richter]

A music synthesizer is a prepatched analog computer. Depending on the
bandwidth of the analog computer you could patch up all the electronic
music modules. The early Electronotes designs all used multipliers as gain
control elements (before OTAs).

A VCO is an integrator into a comparator looped back to the input of the
integrator thru a multiplier. The comparator threshold sets the triangle
wave amplitude and the multiplier coefficient sets the frequency. The
output of the integrator is a triangle wave and the comparator is square
wave.

A state variable VCF is a summing amp - multiplier - integrator -
multiplier - integrator looped back to the summing amp. The multiplier
coefficients set the VCF pass frequency. This is the exact filter that is
in an EML 101 BTW.

A multiplier is a ring modulator. If you put a limiter to prevent negative
excursions of one coefficient its a VCA.

The function generators are distortion units.

A gate signal into an integrator is an envelope generator.

These are all linear functions so you would need a MIDI Volt/HZ converter
to run it from MIDI. The CV outs of a APIA Fatman would work. Even if the
bandwidth of the computer is only 100HZ - you have the biggest
sub-patchable control voltage generator (LFO's and envelope generators).
----------
> From: Matthew S. Padden <m.s.padden at hud.ac.uk>
> To: synth-diy at horus.sara.nl
> Subject: Re: Analogue Computer knowhow?
> Date: Wednesday, October 15, 1997 10:12 AM
> 
> John P wrote:
> >
> >Sounds cool!
> >
> >Could you possibly post a photo?
> >
> 
> I'll see if I can get a scan done; if I can then I'll stick the image on 
> the ftp site here and post the URL.
> --
> Matthew S. Padden
> Computer Music Research Group
> Room M5/14
> Music Dept.
> Huddersfield University
> Queensgate
> Huddersfield
> England HD1 3DH
> p: +44 1484 422288 x2402
> f: +44 1484 472656
> e: mattp at mindless.com
> --------------------------------------------------------------------
> "The masses are asses and need Tonto's glasses!" (Mark Mothersbaugh)
> ----------------------