[sdiy] Re: FPGA 2-OP FM MIDI Polysynth

[Donald Tillman]

   > Date: Sun, 03 May 2009 12:24:16 -0700
   > From: Scott Gravenhorst <music.maker at gte.net>
   > 
   > Here is 16vFM-2x4, a 16 voice version is now working, same structure, just double
   > the voice count.  The 16 voice PicoBlaze-based MIDI controller (with LCD code
   > included) uses 3/4 of the code space allowed (727 instructions).

Scott,

Are you aware that the DX-7 used no real-time multiplies?  Fast
multiplies were extremely expensive in 1983.  And fast multiplies were
absolutely required for digital filter implemetations in subtractive
synthesis, but not required for FM Synthesis.  And that was the major
incentive for the existence of the DX-7.

(The DX-7 stored the log(sin()) values in the sine lookup tables, and
the rest should be obvious.)

If you used the DX-7 algorthm, you might be able to cram many more
operators and voices on there.

   -- Don

-- 
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com