In 1983 Sequential Circuits focused on the Japanese market, dominated by Yamaha, Roland and Korg. To launch the product aimed at a Japanese buyer, local factories were given the original operating system of Six-Trak synthesizer and Curtis CEM3394 chip. After a while, Japanese developers introduced a synthesizer called Pro-8. And after making minor changes which the management demanded to introduce, Split-8 appeared on the shelves.
Split-8 is an extended version of Six-Trak. The external design of the synthesizer underwent the greatest change - its housing reminds more of Roland synthesizers than of Minimoog, the classic design of which used to be based on Sequential Circuits.
The internal architecture remained practically unchanged: the microprocessor Z80 controls an analog circuit based on CEM3394 via DACs. The CEM3394 chip is a "monophonic synthesizer", which contains: VCO, VCA and VCF.
Split-8 features:
One voltage-controlled oscillator (VCO) for each of the eight voices. Switches are used to set any combination of triangular, sawtooth and square wave. Pulse width modulation (PWM) is available.
For each voice, the coarse tuning is available within four octaves as well as the fine tuning.
Programmable "poly mod" allows the audio output of one voice to feed another's VCF. In this case, the polyphony is reduced to four voices.
The voltage-controlled low-pass filter (LP VCF) has a four-stage structure with a slope of 24 dB per octave. Cutoff, resonance and modulation depth adjustments are available. A keyboard tracking mode is also provided (higher notes have a higher cutoff frequency).
The low-frequency oscillator (LFO) produces a triangular or rectangular waveform in the range from 0.25 to 20 Hz. It can be used to modulate the cutoff frequency of VCF, the pitch of the VCO and the pulse-width modulation.
ADSR envelope generators for VCF and VCA.
Keyboard "split" and "layer" functions are available.
Programmable chorus effect.
Full MIDI support, including downloading presets via the sysex protocol.
Unfortunately, at the time of Split-8 release, the market was not interested in analog synthesizers. Back then musicians wanted to have a "progressive FM-sound" featured two years earlier in Yamaha DX7.