[sdiy] Kawai SX210 and SX240 DCO poly.

[KD KD]

In my ongoing and some what irregular .....skip..... previously my Poly61
examination, i have now arrived with my smelling horse at the Kawai
history dump.

SX 210 single ramp DCO (Roland JP8) with subosc (Roland Juno60) and SSM2044
VCF and 2 quite clever ""logic"" based ADSR's similar principle as Juno6 but 2
separate ADSR EG's for each voice.

SX240 even more so stylish dual DCO ramp (model JX3P) and sub (Juno60) DCO2 only
a square wave yet selectable octave, and the same clevery designed ADSR's Same
SM2044 VCF. The 240 have a osc mode known as BRASS each DCO feeds a
diode who's anded. 210 has variable 6db HPF and the 240 has a dual 6db HPF.
Both have master VCA at the rear end to set patch volume.

A interesting issue are the Ensemble unit very similar to Korg poly6, two 3phase
oscillators mixed into 3 composite each feed to a multivib VCO who in
turn drives
a MN3009 BBD multiply this by 3 and your there. Each BBD have compressor and
expandor. Unfortunately no speed adjustment as per Poly 6 but you could modigy
and steal for instance the noise VOL CV or better yet take the LFO to VCA CV
signal for some real wash.

Another peculiar design move are VCA's, for each voice is a
differential PNP mirror who
are summed into one differential instrument amplifier (typical 3OP amp
classic design).
Clever design since it saves a lot of components.

The SX240 have 12VCA's arranged in 8+4 for dual by 4voice poly by simply
turning off/on 4 of the VCA's to create the dual 4voice split/layer mode.

Dual 8031, 8253 for the DCO's and a surprisingly high resolution on the synth
parameters, CV's are created by a discrete 10bit DAC who feeds a temp comp
expo. 1 prescaler for each DCO and a master LCO clk for bend/vib.

SX210 and 240 have various split-mono-layer modes as it seams.

If kawai had supply these two machines with knobs/sliders in the same
way as Roland
did with Juno 60-106 Roland would have faced a serious challenge. Add ensemble
speed and arpeggio and they would have killed off the Korgs and Rolands.

Thank you for your attention and the opportunity to yet again waste your time!
Im most delighted! 8-)

Regards
Kurt Donnegut!