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Sunday, July 22nd, 2018 10:47 pm

Synth Glossary

Pulse Code Modulation is the ability to modulate the pulse width in a square/pulse wave. (NB: A pulse wave is a square wave with 50% pulse width)...


The Multi-Trak, the successor to Sequential's Six-Trak, is a 6-voice, polyphonic, multitimbral, programmable analog synthesizer with MIDI, a sequencer, an arpeggiator, and a 5-octave, 61-note (C-C), keyboard that is both splittable and velocity-sensitive. Like the Six-Trak, each voice consists of a single Curtis 3394 chip, which basically contains the entire synth engine (one VCO, a VCF, a VCA, and an LFO) except for the ADSR envelope generators. The VCO has coarse and fine tuning, glide (portamento), and available sawtooth, triangle, and pulse (with pulse width modulation) waveforms. Each oscillator can be mixed with the noise generator. The filter section features controls for the cut-off frequency, and resonance. Keyfollow modulation can be set to off, half, or full keyboard. The filter is self-resonating and can be modulated by the oscillator. In each voice the VCO, VCF, and VCA have their own ADSR envelope generators with variable envelope amounts. Both the VCF's and the VCO's ADSRs can be inverted. The LFO can be routed to the VCO, the VCF, and pulse width modulation. Available waveforms for the LFO are square and triangle with controls for amount and frequency. The Multi-Track also has a built-in chorus with controls for rate and depth.

Like the Six-Trak, editing is still done with parameter access and a single data knob. However, the Multi-Trak's parameter select buttons are designed around a 4 X 10 matrix, making it a bit more intuitive to program, with one button choosing the row of parameters and one choosing the column.

Each voice can be programmed to any of 100 internal patches and played (via an external sequencer or external keyboard controller) as a separate monophonic synth. Also available was a built-in 1600 note sequencer with quantizing at 8th or 16th notes, 8th or 16th triplets, and a "hi-res" quantization at 96th notes. Also available is an internal metronome. However, like the Six-Trak, there are no memory locations to save your sequences. Instead the Multi-Trak has 4 pre-programmed demo sequences. The sequencer is syncable to an external source.

The Multi-Trak features an improved arpeggiator, polyphonic portamento (in polyphonic mode), unison mode, and "Super-Stak" mode. The arpeggiator has latch, and transpose. It can be switched to up, down, or assignable mode, which arpeggiates notes in the order they were played. It can be set to play on voice six as a chord is played with the other five voices. The Superstak mode allows stacking of two or more voices (each set to a different timbre) together, creating a complex monophonic sound. It is also able to create a three voice duophonic stack. Both mono and stack modes are selectible between single and multiple triggering modes. The Multi-Trak also features an auto- tune function which constantly checks and tunes any voice that hasn't been used in the last 30 seconds. The keyboard can be split into three areas. The Multi-Trak also transmits and receives MIDI velocity. The modulation wheel controls the LFO amount. The Multi-Trak's patches and Sequences are backed up via the cassette interface on the back panel. Also on the back panel is the MIDI interface (IN\OUT, still no THRU), a stereo audio out jack which doubles as a headphone jack, and a footswitch (sustain) jack. In addition to a stereo output, the Multi- Track has six separate outputs, one for each voice. However, both sets of outputs can be used in tandem. Whichever of the separate channel output you plug in to, will be excluded from the stereo outputs, so it is possible to use one or two separate outputs without their signal showing up in the stereo output.

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