Kawai SX-240 (1984)
8 voice programmable polyphonic synthesizer

 

Anlog polysynth from the mid 80 era with neat Midi, also branded as TEISCO SX-240 technically the same.

The sx240 never been considered as a sought-after classic as the ROLAND JUNO 60, but recently it has been reconsidered by many people.

KEYBOARD 61 keys keyboard.
The main panel features a 8 segments display, a pitch bender, 39 buttons, a big data encoder and 2 volume sliders.

Rear panel terminal connectors:
- main stereo signal out (with 3-ways impedance switch)
- Midi interface
- damper pedalswitch input
- tape interface
- reset button
- start stop sequencer pedalswitch input
- phones out.

 

 

VOICE main SX board is based on two 8-bits INTEL CPU 8031 (master + slave) manage 8 voices polyphony. Each voice is composed by two Digitally controlled oscillators (DCO1 and DCO2) + 1 suboscillator and a dedicated white noise generator.

	DCO1	DCO2	SUB
waveforms	summable saw and square	square	square (1 oct below DCO1)
rectangle width	yes	-	-
detune	-	yes	-
ring modulation	1>2	-	-

PERFORMANCE :
- split mode keyboard into two sounds (voices can be assigned in 2+6 / 4+4 / 6+2)
- dual mode play two sounds (LOWER+ UPPED) at the time reducing polyphony to 4 voices.
- monophonic mode
- portamento with glissando effect
- chord mode
- bender can be assigned to standard pitch or filter cutoff.

FILTER multimode resonant filter HPF + 4 poles LPF based on 8 chips SSM 2044.
For some strange reasons, the resonance self-oscillation is abruptly reached from step 98 to 99.

 

ENVELOPE two main EGs both 4 segments ADSR structure:
- EG1 VCA amplitude
- EG2 VCF filter
EG VCA can be switched to special LFO TRIG (auto-trigger) REPEAT mode driven by LFO frequency (range from 1 to 20 Hz).

 

LFO a single bipolar delayed modulator (shapes: square, sawtooth and triangle) and 3 destinations:
- DCOs pitches (whole)
- VCF cutoff filter
- DCO1 rectangular width (PWM).
The LFO can be triggered or stopped using the dedicated buttons

 

FX the internal ENSEMBLE is an analog chorus board, should be based on MN BBD (not sure).

 

SEQUENCER primitive real-time 1500 notes sequencer it can be synched to external trigger (like Roland TR-606). The Sx240 can be also controlled and sequenced by MIDI, too bad it handles quite nothing but note ON/OFF and for some really stupid reasons: you cannot control the LOWER part by Midi.

MEMORY:
- 48 patches (the "tones)
- 8 sequences (each 190 notes max).
Data can be saved only to tap as the Sx240 midi interface does not feature sysex protocol.
Battery replacement: Ni-cad 3.6V rechargeable battery, possible leakage if machine not used for long time.

 

AUDIO DEMO

favourite: Dolby layer favourite: Bass organ favourite: brillant brass favourite: pad wash favourite: chorused EP favourite: Rhodes SX favourite: brass synth favourite: fun sequence Sequence: Bach Wendy Sequence: A C64 game organ: Hammond B3 Synth: movement Synth: plastic Synth: nervous Synth: liquid Synth: line Bass: smallt Bass: bassline LFO Bass: dual Bass: tb303 Pad: chorus Pad: creepy Pad: desert Pad: filtered Pad: lfo

Pad: tiny sound Pad: major Pad: progressive FX: reverse ambient FX: oscillation FX: horror FX: motor FX: Sample hold FX: Warp Sulu   TEST: DCO1 SAW WAVE TEST: DCO1 SQUARE WAVE TEST: DCO1 SQUARE WIDTH TEST: SUB OSCILLATOR TEST: DCO2 DETUNE RANGE TEST: NOISE GENERATOR TEST: BRASS MODE (RING MOD) TEST: ENSEMBLE EFFECT (CHORUS) TEST: PORTAMENTO TEST: ADSR TEST: ALL LFO SHAPES TEST: LFO REVERSE MODE TEST: VCF LOWPASS TEST: VCF HIGHPASS TEST: EG LFO TRIG

Soundcloud Kawai SX-240

VIDEO CLIP SELECTION Demo 1 Demo 2 Demo 3