additive

[Tony Allgood]

Malcolm said:
Maybe you could use 2 or 3 VOCs to feed 8 or 16 frequency
multipliers each with a VCA and ADSR.  Whew!  Maybe by de-tuning the
VCO's just a little you might avoid the problem that Bill Layer
mentioned


This is alright, but do not expect rich waveforms or swept filter sounds. An
adsr on each harmonic will not produce swept sounds unless you delay the
triggering. You are much better off using a Walsh bank, see Neil Johnson's
site. If you want enveloped sines then use a DX7 or similar like a previous
post suggested. Detunes are easier too. But you will not be thrilled, since
it will sound like a Hammond organ. One way to get good additive synthesis
is to use a piece wise linear voltage generator (32 steps) for each VCA.
This may give you nice moving textures but it takes a long time to set up
unless you have a Fairlight and a light pen. :-)

I had such a generator with 8 tri harmonics, but it was sadly too much
hassle to use. Give me two VCOs with sync and audio rate PWM any day. Having
said that, one of these days I will dust off my Walsh bank and update it.
This was more successful, but it never got further than eight Eurocards
stuck to a piece of ply-board.

Regards,

Tony Allgood, Cumbria, UK

e-mail: oakley at enterprise.net

Rack mounted Moog VCF module. Details to be found at...

http://aupe.phys.andrews.edu/diy_archive/schematics/effects/filter.html