[sdiy] Decoding Kawai K3 Waveform ROM's

[Plutoniq9]

*This didn't seem to post to sdiy when i posted to ah last nite.

Hi,

I've been interested in creating a new waveform ROM set for the kawai K3/m 
for quite a while now and have been making great progress the last few days. 
  However, it uses a method of storing waveforms in a very odd fashion;

- Uses 2 ROM's (#09 & #10) for waveforms, but uses them in 
combination/parallel (not just to extend memory space).

- ROM #09 is 8-bit Unsigned INT 32,768-bytes. Rom#10 is 8-bit Signed INT 
32,768-bytes.

- ROM #09 is 32768-bytes x 8-bit. Each of the 31 waveforms occupies 
1024-bytes of space. Within this 1024-byte space, 5 different octaves of the 
waveform are "interleaved", higher octaves contain less sample data (i.e 
512-bytes, 256-bytes, 128-bytes, 64-bytes, 32-bytes x 2). This is to avoid 
aliasing I imagine.

This much I have figured out. I wrote a small c++ program that has allowed 
me to extract the "base" 512-byte wavefoms from ROM#09. Next step here will 
be to go the other way, convert a 512-byte single-cycle waveform into the 
K3's 1024-byte interleaved format.

HOWEVER........

The second ROM (#10) is still a mystery to me....... The only hunch I got is 
that is may relate to this patent;

http://free.patentfetcher.com/GetPatentPDF.php?f=Pats/US/45/26/US4526081.pdf

But I'm not sure I understand it well enough. If anyone can offer some help, 
it would be greatly appreciated! Ultimate goal is to create replacment Kawai 
K3 wave ROM's containing "cream of the crop" single-cycle waveforms (i.e 
wavestation, prophet VS and various "classic" analogue synth waveforms from 
real machines etc.)

To help, i've created a zip file containing the sine waveforms (both 
de-interleaved and interleaved) from ROM # 9, and the "mystery" 1024-byte 
sine from ROM # 10. I'll also include the .bin dumps of both waveform ROM's. 
The big question is......

What the fudge does ROM # 10 have to do with ROM # 09? Is it to extend 
harmonics like in the patent # 4526081?

Zip file can be found at audiosyn.com/files/K3%20mystery%20waveform.zip

Thanks

Plutoniq9

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