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Prophet T8

A new studio standard?

Mark Jenkins evaluates a new synthesizer from Sequential and foretells the shape of studios to come.

After what seems like an eternity, Sequential Circuits have finally come up with a production model Prophet T8, and all the signs are that it's going to be well worth every minute! Almost certainly the T8 will become the standard studio synth over the next year, and anybody who can afford one will want one for live use as well. What's special about the T8 is that it takes all the well-known Prophet features and adds to them in a way that makes the machine incredibly versatile and expressive.

Dave Smith's basic Prophet 5 design was based on the idea of five Minimoogs played by a single microprocessor-scanned keyboard, with sounds memorised by a digital system. The flexibility of this design was such that the Prophet 5 became the standard for studio or live work, despite the limitation of the 5-note system. The Prophet sound soon became easily recognised on tracks ranging from folk to avant-garde to rock; the filters of the CEM chips used producing a cutting metallic tone when needed.

Other SCI designs over subsequent years made less impact, despite the flexibility of the dual-keyboard Prophet 10 and the sheer pose value of the Remote Prophet keyboard. What was really needed was a Prophet with the classic appeal of a grand piano added to the ultimate of synthesizer sounds. The result, after several hiccups due to design and costing problems, has been the T8.

The T8 has, as its name suggests, an eight-note polyphonic keyboard, the idea of an additional eight-voice expander having been abandoned for cost reasons. Not many 16-fingered keyboard players about anyway, you may say, but the difference comes in the Release stage of a note where the number of pitches holding on has a great effect on the overall texture of the keyboard's sound; for sequencing the rule is "the more oscillators the better" as well.

Heavy Music

The new synth's eight pairs of oscillators are assigned by a choice of methods to a 6-octave (A to C) wooden weighted-action keyboard which responds to both velocity and pressure information from the player's technique; that is to say, various parameters of sound can be altered both by how hard you hit the keys, and by how hard you push down on them afterwards.

Velocity sensitivity is most commonly used to make a sound louder (VCA control) or brighter (VCF control), and it's possible to produce an absolutely stunning acoustic piano sound using these facilities to the full. This isn't just a cheap polysynth electric piano-type imitation substitute sound; this sound is full of life, movement and interest. In many ways it's better than sampled sounds, because the response can be tailored accurately over the length of the keyboard. Velocity sensitivity can be reversed so that a sound which dominates when the keyboard is struck heavily disappears to be replaced by a totally different one if the style is lighter; a neat touch and one which can double the existing Keyboard Split capability.

The pressure sensitivity can control the pitch of both oscillators, the pulse width, filter, amplifier and modulation settings and the speed of the LFO. After setting up a good old 'Hammond and Leslie' sound it's possible to speed up the Leslie effect by bearing down on the keyboard. Incidentally, all these effects are completely independent on each note, so that a lead line sound can have pitch bend or modulation added to it without all the notes of a chord held by the left hand being affected — the Yamaha CS80 being the best example of an older synth offering this facility.

John Bowen demonstrates the 'T8 Split'

The keyboard assign modes are Single, Double, Split and Unison/Track. Single mode assigns one sound, eight-note polyphonic, to the whole keyboard; Double mode layers two different sounds on top of each other with four-note polyphony; Split mode divides the keyboard at any point to give two independent sounds, for a chord and a lead or a chord and a bass figure perhaps; and Unison/Track locks all the oscillators onto one key for a powerful lead sound, or allows a chord to be programmed in and reproduced with any root note.

The T8 is in constant Edit mode so that a memorised sound can be quickly updated without being permanently changed if it isn't quite what's wanted. Another useful addition not seen on the 5 is the 'Second Release', an alternative programmable release length which can be brought in with a footswitch and will usually be used to simulate a piano's sustain pedal. Other goodies include a foot-switch control for the Unison/Track function, full polyphonic glide, MIDI interface and a built-in sequencer.

Lots Of Loops

The T8's sequencer is a bit of a mixed bag, powerful in some ways but limited in others. It has a maximum capacity of 600 notes divided between up to eight patterns, all of which are strictly realtime. They can be programmed slowly and speeded up, but can't be easily stepped by an external drum machine, for instance. Roland's JX-3P gets over this by sneakily correcting the sequence to a pulse and then allowing it to be clocked, but there's bound to be a slight loss of resolution and expression there. Sequential's solution is to call in a computer, of which more later.

The inbuilt sequencer at least has the advantage that a particular sound can be tied to a sequence so that the two always come up together, very timesaving for storage use. A sequence can be quickly programmed in, and looped by footswitch if desired so that both hands are free to play over the top of the sequence on another keyboard, or indeed on the other half of the Prophet's keyboard. The sequencer stores all the information from the keyboard, so that pitch bend, louder or quieter passages and effects will all be reproduced in glorious detail.


At last it's possible to connect synths together without having to spend ages fiddling with mini-jack plugs, linear to log convertors, soldering irons and crocodile clips. Well, almost; the MIDI (Musical Instrument Digital Interface) system adopted by Sequential, Roland, Yamaha, Octave, Siel and others can only be applied to relatively expensive microprocessor-controlled synths, and as yet doesn't appear on any drum machines or sequencers (rumours from Yugoslavia excepted).

When MIDI really gets underway it's going to be pretty amazing, and Sequential are looking ahead by introducing the first commercial MIDI-to-computer interface unit. The computer chosen is the Commodore 64, follow-up to the popular VIC 20, and the interface allows it to provide versatile sequencing and other facilites for the T8, Pro-600 or MIDI retrofitted Pro-5.

No TV monitor is needed, as the cigarette-packet sized interface unit has half-a-dozen LEDs to indicate its functions. The exact functions of the interface depend on the software used, which will be available blown-in to the interface but at the moment is loaded from cassette. One package allows storage of all performance parameters including pressure and velocity information and pitch bend, again in real time with the possibility of a pulse time package in the future. This package has nine locations which can be overdubbed up to the maximum number of simultaneous notes on the synth, and in two different sounds in the case of the T8. Real-time transposition will be possible, hopefully stored as part of the sequence, and memories can be chained to give very long compositions. Unfortunately the use of a disk drive is not on at the moment. The computer uses 10 Bytes per note and the Commodore 64 has 32K available for use, so the maximum length is 3200 notes. Although the Commodore 64 uses a 6510 processor, it should be possible to use other 6502 machines before long, which would include the popular BBC Micro, and Sequential are interested in the Sinclair Spectrum.

MIDI interface and Commodore 64

About six months from now there will be a composing package available possibly using musical notation, and the other capabilities of MIDI are bound to be exploited before long. These would include listing parameters of presets and synchronising video or computer graphic displays.

Drumming Along

As mentioned earlier, the real-time sequencer cannot be clocked externally on the T8 itself, but the interface includes an input which allows clocking via the MIDI. This requires a TTL-level pulse at a variable frequency, but can't work at the level of a simple one-pulse-per-note drum machine such as the Drumatix or Clef. Such digital monsters as the Linn, Drumulator, or Oberheim will happily give the 6, 12 or 24 pulses per quarter note that are needed, but adapting the system for cheaper drum machines looks like being pretty difficult. A demo of the T8 driven by a LinnDrum, however, is best described as stunning, and will send a lot of multitracking enthusiasts down to their friendly bank for a sizeable loan.

In Conclusion

Sequential Circuits are on to a winner with the T8, although its price will inevitably confine it to the professional market. The MIDI-Commodore interface is another question entirely, a tentative first step into a field which promises to become enormously rewarding. Sequential certainly aren't standing still or neglecting their public; despite the fact that the monophonic Pro-One is coming to the end of its lifetime, they're handling a versatile digital sequencer design intended to be retrofitted to it which will gladden the hearts of sequencer freaks everywhere. The next step? Apart from more software for the computer interface, there's one field in which SCI are, as yet, notable only by their absence. Roger Linn look out..?

Prophet T8 £4727.00 (around £4000 in the shops)
MIDI Sequencer/Drum interface cartridge £172.00
MIDI retrofit to Pro-5 incl. labour £161.00
UC-1 sequencer for Pro-1 POA

Further details from local dealers or from Sequential Circuits Inc, (Contact Details).

With thanks to SCI's Product Specialist John Bowen and Sales Manager Tim Oake.

Also featuring gear in this article

Previous Article in this issue

Chip Parade

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Oric Sound

Electronic Soundmaker & Computer Music - Copyright: Cover Publications Ltd, Northern & Shell Ltd.


Electronic Soundmaker - Oct 1983

Donated & scanned by: Mike Gorman

Review by Mark Jenkins

Previous article in this issue:

> Chip Parade

Next article in this issue:

> Oric Sound

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