The Sequential Circuits Six-Trak is best known for being the first multitimbral MIDI keyboard. The Six-Trak is capable of producing six different timbres on six different channels all at once. Even though each part is monophonic, this was no mean feat for 1984 and a $1295 initial price tag. The Six-Trak is a small synth barely wider than it's four octave non-velocity sensitive keyboard. The pitch bend (no spring return) and modulation wheels are above the keyboard, as Sequential chose to keep the unit as compact as possible. The rather spartan front panel has arpeggiator, sequencer, and stack controls on the left, and the programming controls and keypad on the right. Each voice is consists of a single VCO, VCA, and self-oscillating VCF. One unique feature of the VCO is that it will generate a saw, triangle, and pulse waveform, along with noise, all at once. A single LFO and three envelopes are all generated in software. The LFO only offers two waveforms, square and triangle, but modulation destinations include VCA, filter cutoff, and pulse width. The filter can also be modulated by the VCO's triangle wave, although with only a single oscillator this feature is no where near as useful as on the SCI Prophet 5. All six voices can be stacked homotimbrally with adjustable portamento, or the voices can be stacked polytimbrally using the stack mode. All parameter editing is done via a 10 digit numeric keypad. Those familiar with the Ensoniq Mirage will have no problem finding their way around, although SCI did add a data entry knob. The Six-Trak has a rudimentary six track sequencer that although I haven't found a good use for, could possibly be used in a live situation with interesting results. Two sequences can be stored with an 800 note maximum, and no editing is provided other than patch changes. The sequencer can supposedly be synced to incoming MIDI clock by turning the sequencer’s speed knob fully clockwise, but I have yet to see this work. The sequencer section is also where you'll set the patch number for each MIDI channel if you choose to use the Six-Trak polytimbrally. One of the coolest features of the Six-Trak is that it is fully programmable and editable in real time via MIDI continuous controllers. Simply transmit a CC number that is two higher than the corresponding parameter to be edited. This works extremely well in conjunction with the external audio input modification. The mod allows you to filter and mangle six different audio sources in real time. This is the main reason I own my Six-Trak. NoteIt's SixTrak and SCI Pages with Multiple Output Mod