Sequential Circuits (SCI) SixTrak

1984, Full Midi, 6 VCO polyphonic analogue synthesizer.

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 is a shame it doesn't have realtime 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 realtime 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 noticable at the bass end and does not happen when controlled via MIDI controller numbers, I haven't done it yet but just imagine this with a full set of MIDI controllers from a knob bank!

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"!

Sounds

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 SixTrak 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 un-quantized 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, think Street Fighter or something! With computer multitracking I have no real use for the sequencer aspect.

It's oscillators are voltage controlled but it seams to warm into tune over 5 or 10 minutes rather than go out of tune over time. Tuning is not a problem, there is an auto-tune function and a manual tune knob though I never really hear it drop out once it has warmed up.

MIDI

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 seam 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 must have 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 :)