[sdiy] interesting patents- Yamaha, Kawai, Ralph Deutsch

[Scott Gravenhorst]

Scott Nordlund <gsn10 at hotmail.com> wrote:
>
>Somewhat relating to recent discussion of interesting digital 
>synthesis technology (DX7, Synergy, Synclavier, some weird Sony 
>thing), I've found a bunch of oddball patents for ideas that 
>apparently never made it off the drawing board.  Unlike better 
>known technology (Chowning, etc.), it seems to be mostly 
>forgotten.  Google Patents links to cited patents, so there are 
>hundreds to look through. 
>
>Yamaha and Kawai were apparently both heavily into digital 
>synthesis research in the 70's.  There are all sorts of patents 
>for digital filtering, additive synthesis, digital envelope 
>generators, etc. years before any commercial implementation.  A 
>lot of them relate to very specific hardware or stuff that's 
>mundane now, but there's still a lot of good reading material. 
>
>Ralph Deutsch comes up a lot.  He was involved with the early 
>Allen Organ digital stuff circa 1971, and kept designing at least 
>through the mid 80's, with some of the technology eventually 
>making its way into the Kawai K5 and probably numerous organs. 
>
>A few examples of strange stuff (all Yamaha):
>4282790 windowed chirp synthesis, 1979
>4135422 strange sine-based synthesis, 1979
>4249447 waveshaper feedback synthesis, 1981
>3994195 sin-cos product (??) synthesis, 1976
>4655115 amplitude modulation feedback synthesis, 1987
>4223582 phase distortion (?), 1980
>
>Maybe some of these could find their way into FPGAs...

Heh, they could at that.  Though I've not yet read these patents, I've been working on what I would
call "waveshaper feedback synthesis" or perhaps "strange sine synthesis" where I have used sine
oscillators with other than simple feedback to produce more waveshapes than the almost-sawtooth.  

A while back I did some experiments with trig identities to "morph" between sin(wt) and sin(2wt)
and a couple of others.  I dropped it because it was mainly underwhelming.  Perhaps these patents
will show me things with more whelm.

-- ScottG
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-- Scott Gravenhorst
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