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

Johannes Öberg johannes.oberg at gmail.com
Mon May 4 14:51:49 CEST 2009

Reply to various posters

4-op FM vs 2-op FM is like toy keyboard vs serious synthesis platform.
Worlds apart in power. Especially if you have many feedback

If you add non-integral carrier/modulation frequency relationship you
get a whole new dimension of possibilities, not just inharmonic
sounds, but you can make some of the harmonic sounds *much* better by
adding a little beating.

If you have the DSP power for multiplies, my tip would be: use 4-op
Phase Modulation synthesis with derived waveforms (like the TX81Z)
with log tables, and use the multipliers for analog style envelopes,
good subtractive filters and effects (FM sounds generally takes very
well to a touch of chorus and delay, and some sounds really come to
life with a bit of overdrive). Make it multitimbral, and voilà, it
might be the only synthesizer you ever need.

> I have a feeling, however, that the DX7's strange/unpleasant (IMO) envelope attack (which I
> brought up on another mailing list) is also partly due to the anti-log lookup table.

I thought this was because of bad (linear?) envelopes and low resolution?

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