The SIX-TRAKS is a multi-timbral polyphonic synthesizer. It lets you play six completely different instrument sounds at one time. And you can do so in three ways. One way is by layering several instrument sounds on top of each other so that you can play them in unison from the Six-Trak keyboard. Sequential Circuits calls this new, multi-layered unison technique our "Stack" mode. Another way of playing the Six-Trak as a multi-timbral "ensemble" is by recording six different instrument sounds into the Six-Trak's on-board multi-track digital recorder. Push one button and the "band" plays. The Six-Trak's multi-track recorder (or sequencer) is packed with all of the functions needed to qualify as a professional music tool. Functions include Record, Playback, programmable playback speed, programmable track volume changes, variable-resolution error-correct, track duplication, and over 800 notes storage capacity. A third method for creating complex, multi-part music on the Six-Trak is by combining the live playing capabilities of the instrument with its multi-track recording feature. For instance, you might choose to record a bass line on Track #1, a guitar on Tracks #Z and #3, and a fiddle on Track #4. This lets you reserve two voices for playing a "live" banjo solo on the keyboard during playback.
The Six-Trak is a 6-voice polyphonic fully programmable synthesizer featuring six real VCO's and six 4-pole filters. The synthesizer program memory stores 100 programs, each consisting of 33 voice parameters. LEDs clearly indicate the selected program, and if the program is being edited, will also display the parameter number and parameter value. Parameter values are edited with a single knob. Programs can be copied. And the non-volatile memory is retained when power is off thanks to a ten-year backup battery.
Each voice has a multi-waveform oscillator (or noise) as the principal sound source. A PITCH wheel is provided for bending notes. The oscillator is followed by a resonant low-pass filter which contours the timbre, and an amplifier which contours the dynamics. There are three ADSR envelope generators: for oscillator frequency; filter cutoff frequency, and amplifier gain. (The polarity of the first two can be inverted.) A triangle or square wave modulation LFO can be applied to oscillator frequency, pulse width, or filter frequency. Modulation depth is both programmable or adjustable by the MOD wheel. A second modulation route runs from the oscillator triangle output to the filter frequency. Frequency glide (nportamento") and voice volume are programmable. Non-programmable master volume and tuning controls are provided. The TUNE switch has been eliminated by fully-automatic oscillator tuning. The back panel has jacks for audio output (which can drive stereo headphones), a multi-purpose control footswitch, and MIDI input and output. MIDI is the technical link to the future. Today it allows the integration of the Six-Trak into one programmable system including SCI's new Drumtraks and Model 64 MIDI sequencer. The synchronous link to the Drumtraks adds an entire programmable rhythm section to the multi timbred ensemble. The Model 64 sequencer offers increased sequencer storage-to 4000 notes, program storage on cassette or disc, sequence transposition, alternate keyboard modes, as well as forthcoming music display and editing functions.
