SCI Six-trak

1984, Full Midi, 6 VCO polyphonic analogue synthesizer

SCI Sixtrack

This is a compact little power-house of analogue warmth and character. It may be the little brother of the SCI series but with 6 note polyphony, 6 voice multi-timbral stacking and full CC midi control I rate this very highly indeed. It’s sound is vintage and kinda dirty or gritty.

It is a shame it doesn’t have knobs all over it, but I still find programming it is great fun and produces a rich diversity of sounds. You can have one controller at a time assigned to the knob so you do have hands-on control over filter cutoff etc if you need it. There is stepping when controlled this way due to the 121 steps used to store patches but this is only really noticeable at the bass end and when parameters are moved very slowly.

The pitch bend wheel is a bit dodgy as they hadn’t fixed an accurate note range like +3/-3 for eg, plus it is not spring balanced, but you get used to it and this doesn’t effect the midi response. I guess the pitch bend can be adjusted with a variable inside but even the manual says “about a 3rd”!


The 100 factory presets show off some potential but there were also a lot of pointless patches (imo) so I’ve been through tweaking and saved loads of my own patches for future inspiration. For example find a sound in the presets that you don’t like; tweak it into something inspiring and save it over the top.

In polyphonic mode it can create gorgeous overlapping synth textures reminiscent of powerful Jarre strings and bright Vangelis brassy leads. I often use the limitations of the 6 note polyphonic release to advantage in creating cleaner more controlled pads.

In Unison the Six-Trak is a huge 6 oscillator bad boy capable of breaking your speakers, use this with caution as I have resonated my house to the point that things are falling off shelves! It is pretty harsh when it’s going full-on like that but the unison sound can be moulded to make it much warmer and more usable.

It also has a Stack mode which allows you to use the 6 voices as independent sounds on top of each other. This provides a whole new aspect to creating layered sounds and you can save two multi-patches with the two stack buttons. It’s simple onboard sequencer allows you to create an unquantized 6 track multi-timbral arrangement though I’ve never fully explored it. The two demo sequences (see below) show this off in a old skool arcade game kinda way.

It’s oscillators are voltage controlled and sound out of tune when first switched on, they are designed to warm into tune over 5 or 10 minutes as the electronics reaches working temperature. Tuning is not a problem, there is an auto-tune function and a manual tune knob which I leave in the same place all the time; I don’t remember it ever going out of tune once it’s warmed in.


The midi spec is complete with control over every parameter via standard midi controller numbers. This in itself provides a lot of flexibility and creativity while making patterns for a tune.

While running a lot of midi data through it the onboard editing becomes virtually unusable as the parameters seem to conflict and you see the numbers moving on its little 2 character LED screen, however as long as you aware of this its fine; ie stop the tune before tweaking.

SCI intended this to be part of a midi setup as it even has keyboard local on/off which hardly any synths of this age would have had. It is apparently the first multi-timbral midi synth ever though correct me if I am wrong.

Quote from the manual:

“Note: MIDI is an evolving system. We encourage you to experiment with various instrument configurations and let us know what, if any, other control options would be useful to you.”

Well SCI, its over 20 years on and I’m quite happy as it is thanks 🙂


Audio Samples

Continuous Controller List


  • Kenneth says:

    So I have lost all the sounds from my six trak any idea how i can get them back?

    • Chris says:

      Hi, yes should be fairly easy, the bottom link here has all the syx files you need: You just need a Sysex librarian type app on your computer to send the data across.. Should be the same procedure as for the Multitrak, have a google on “restore factory patches sixtrak” .. But if you’ve lost the sounds maybe your battery is dead? Thats an easy fix too, I did that one myself.

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