[sdiy] Korg DSS1 DMA oscillators, the old beast!

[karl dalen]

I had a DSS1 back in 1987 i remember it was a nice synth but a less lot as
sampler due to the hilarious OS and the way it handled samples. As a synth
it was as straightforward as the DW8000 was. I always considered it an
vastly expanded DW. 

Regarding to discussions around the various principles ESQ1, K3,
DW8000, PPG  are based around i wondered how the DSS1 did it.
(btw. who in his right mind scans an entire service manual so unreadable?)

http://img14.imageshack.us/img14/6212/dss3.jpg
http://img691.imageshack.us/img691/7066/dss2.jpg
http://img715.imageshack.us/img715/3315/dss1.jpg

It appears that DSS1 are a true variable sample rate system with
crude Bw limiting in Wave Draw and Additive modes but not in sample mode
according to T0 to T15 producing the musical note (variable sample rate)  but how does this DMA actually work as variable playback mechanism to
generate the actual sample tone? I thought DMA was about shuffling data
as fast as possible from various nodes in a system! Timed bursts of 
DMA data would give audio silence!

EMU Dave talks in an interview that he had figured out DMA as a technique
for sample playback, he regretted he didn't patented that! (Emulator1 days). How does a Emulator1 oscillator work? Also the last one to use
variable sampling rate was the 16 bitter Emu III. 

In most Fairlight ad's if anything are spoken about sampling it says it
was based around variable sample rate, and since the Fairlight used
separate cards for each voice did it generate this playback by the
same DMA mechanism?

How did the Series III do it, same card but a 68000 configured as phase
accumulator? Or are the all models based around phase accs and DMA only
for data transfer?

I have a block diagram of the Synclavier some where (cant find it right
now) in which 24 bit phase accumulator are drawn which makes sense since
the original Synclavier was a FM machine with sampling added later (mono
sampling for years).

I figure the Synclavier and Synergy would be of similar oscillator design?
(minus the phase duality of the Synergy).

Noise in the DSS1 are generated completely analog by something
old fashioned as blurbing PN junctions! :)

Btw, the DDS1 and Poly800 uses the same NJM2069 VCF-VCA combo.
Time to do a small hack folks?

Reg
KD


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