[sdiy] FPGA Synth Music

[Scott Nordlund]

> Has anyone else here had the pleasure of hearing the Con Brio ADS 200? I
> have and the sound was breathtaking. Makes a Yamaha 4 or 6 op synth sound
> like buzzy radio in comparison. The bell tones were especially clear and
> harmonious, without the clang I associate with Yamaha FM. Pretty amazing
> that they could do 64 voices of polyphony with 16 op FM back in 1980. I
> spoke with one of the developers a few years ago when Brian Kehew drug his
> ADS 200 up to the Computer History museum in Mountain View. They used some
> hardware multiply accumulators for the math and a couple 6502s for control.
> It's truly a shame all the documentation and code was thrown out in 1990s.
> It would make a spectactular hardware synth if implemented in FPGA. I'm
> guessing there were some design decisions done in the control software that
> contributed to it's unique sound. I didn't think the controls were very
> intuitive but I'm not sure anything can make 16 op FM intuitive.
>
> -Cary

Hardware multiply is (was) the complicated way to do it.  I think the 
Synclavier did the same for its FM voices (at least for modulator scaling),
and it used an absurd amount of hardware for some fairly primitive FM (2 
operator, user definable carrier with 24 harmonics, sine modulator).  

I don't know how Yamaha's "log sine" compares with the Synergy's more 
eccentric "phase shift and add" in this department, but I guess it's still
relevant to FPGA-based designs.

I wouldn't think there would be anything inherently superior about the 
Con Brio (or Synclavier or Synergy), though, aside from the number of 
operators, and possibly sample rate (variable sample rate?) and sine ROM
resolution.  Bessel functions are still Bessel functions.

Anyone know of any patent numbers for the Synergy, Synclavier, Kurzweil 
K150, Kawai K5, or anything else like that?  I've seen the Yamaha patent
that covers the DX7.
 		 	   		  
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