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Prophet T8

In depth.

The last time One Two carried out an in-depth study of a poly synth, it was the famed Yamaha DX7. If you were to compare a list of the DX's facilities with one of this month's device you might gain the impression that they were brothers under the skin, or at least cousins.

Both keyboards have large memory capabilities (the Yamaha with the help of plug in RAM packs), you can layer and split sounds, but most significantly of all, the keys themselves can introduce countless extra effects depending on how hard you hit them, and what you do once you've made contact. They feature what are known as second touch keyboards. Strike the key once and the note will sound, but press it down harder and you activate switches that can produce vibrato, pitch bend and other performance modulations, depending on how you've got the machine set up.

A stick of chalk and a Silk Cut are both long and white, but only one catches light. The DX7 and the Prophet T-8 are nothing like each other, no matter how their catalogues may match up. For a start the Yamaha is based on digital synthesis and the Prophet is good old analogue, but the fundamental differences go further than sound generation.

The Yamaha is a dazzling example of high technology which is capable of offering the musician a host of fascinating sounds, effects and applications. The Prophet works the other way round — a set of ideals and desires expressed by many keyboard players then followed by a machine which is built, refined and fashioned in order to meet them. It's the difference between 'this does...' and 'do this...' Enough of the metaphysics, on with the metafactual.

The T-8 is obviously based closely on the Prophet 5; why muck around with what is still the world's most famous polyphonic synthesiser? There was a time when the word 'Prophet' was the 'Hoover' of the keyboard business.

The T-8 has been around in prototype form for a long time... a year and a half?... two years maybe. Sequential Circuits first announced their ideas for a touch sensitive polysynth shortly after Yamaha discontinued the CS80's, which were also built around dynamic keyboards. Trouble is, you had to be fairly dynamic to play them. They weighed a ton and seemed to cover as much floor space as a Cortina.

The T-8 keeps the standard teak end cheeks and black and white control panel but is at least 12in wider than a Prophet 5, partly to contain the extra electronics but mainly to supply the right feel to the keyboard.

For this is a weighted, wooden, six octave 'board, designed to play as much as possible like a piano, with the right degree of bounce and balance. This can only be accurately captured by having a reasonable length of key beyond the fulcrum point. Shorter keys aided by springs can't recreate it.

There are 128 fully programmable sounds divided into two batches. The T-8 features 8 push-buttons numbered 1-8 which call up the programs, but each position — 21, 44, 88 whatever — has a left and a right sound, selected by extra buttons on the front panel.

They are also displayed separately, each has its own red LED readout. The T-8, as its name suggests, can play a maximum of eight notes at once. So you could have eight notes of a left sound all the way across the keyboard, eight notes of a right sound, four notes of a left and a right laid on top of each other, or four notes of a left at one end of the keys, four notes of a right at the other. The crafty among you will have identified this as a split and layer keyboard, not dissimilar from a Jupiter 8, for example.

One for the many. In these days of 100-plus memory banks, it's not the chips that cause the problem but the mass of control buttons required. The left and right system is one way of avoiding dozens of switches, but initially it's confusing. I was never entirely sure what program I'd selected, and the Prophet's method of scanning its keys can land you in serious brown stuff if you're not careful.

Sometimes when I went to a memory position that had been programmed as a layered patch and tried to select one side of it, I'd find that the first four notes I pressed would sound, then the next four would be silent since the T-8 thought it was off working on the other half. The third set of four would sound again, and so on.

And with so many programs at your disposal, it's only natural that you should want to layer together different selections. Easy, pick your left sound then your new right sound, press the double-up button and away you go. Spot a flaw? Yup, you can't easily pile a left sound on to a left sound, nor a right on to a right effectively cutting you off from half the possible combinations. The only way round it is to reprogram the desired left sound into a vacant right position, or vice versa, which takes that much longer.

Ipso facto, though the keyboard can be split anywhere, and the split point held in the memory, you can't put a left sound on the right hand side of the keyboard and... well, you know the rest.

The 'stereo' memory is cunning, but it can be limiting. Familiarity will get you round those drawbacks, but the T-8 is neither faultless nor failsafe.

Incidentally, the difference in volume between the two 'sides' of the sound can be written into the original program, or varied by a balance control to suit your performance. New programs can be written once you've flicked off the disable switch on the back panel, and the T-8 like other Prophets, is in continual edit. Once you've given the controls a slight tweak, they leap back to their panel positions — still, to my mind, not as elegant a system as, say, Oberheim's where the edited controls move backwards or forwards from their programmed values wherever they happen to be pointing on the panel.

Onto the meat and potatoes — the touch sensitivity. First off, the T-8's dynamic keyboard system is about the best I've ever tried. Not only is it well thought out and generously equipped with special effects, but when you dig into the pianolike keys with a murderous grin on your face, it fights back. You don't fear that certain plastic pins are being fractured deep within the synthesiser's bowels.

The effects split into two halves — those associated with keyboard velocity (how hard you hit the keys to begin with), and those centred around second touch. The former are laid out in a row of four controls in the top right hand corner of the panel. They govern attack/decay time, release time, envelope peak for the filter and envelope peak for the amplifier. On each control the centre position is zero, generating no effect. Taking the filter peak as an example, a setting of plus 5 (all the way clockwise) will cause the filter to open up when you hit the keys hard and close down when they're played softly. But a setting of minus 5 does exactly the opposite. And that is weird. The heavier you hit the keys, the softer the sound becomes.

The same applies to the amplifier envelope which governs the overall dynamics and volume plus the attack/decay (gently pressed keys can give strings a longer attack, for example), and the release. ALL can be programmed into the memory.

Two for the flow. The plus/minus method is a brilliantly straightforward idea, easier to grasp than the DX7's system and far faster to set up. And because of the positiveness off the piano-weighted keyboard, I found that playing became not only more expressive, but smoother, and there wasn't the fear that if I whacked the keys really hard, I might accidentally trigger the second touch switches — a worry that always nagged at the back of my mind with the DX7.

Which leads us neatly on to these very effects; this time a collection of knobs in the top left hand corner of the panel. The T-8 still has its pitch bend and modulation wheels, but now the extra pressure of a finger can influence the frequency of oscillator bank A, oscillator bank B, pulse width, VCF cutoff, VCA amount, LFO amount and LFO frequency.

The first two are responsible for a broad range of consequences — imitating the slide of a fretless bass by slurring the pitch on runs, accentuating the flare of a brass part by causing the frequency of the oscillator banks to part slightly for that additional 'blart', and introducing finger controlled syncing sounds by having the pitch bend up full so the slightest pressure sends one of the oscillators soaring.

The pulse width, amp and filter controls can be used to set up modulation effects of their own, or be combined to reinforce each other. With the LFO frequency variation, you're now able to speed up the Leslie on your Hammond impersonation just by pressing harder on the keys.

And with the T-8 it's worth remembering that EACH key operates individually. Push one and the second touch activates on just that note. Many dynamic keyboards have a single switch so as soon as the keyboard hinges down, everything cops the same amount of vibrato, filter cutoff etc. Another ten marks for subtlety and expression.

The only time you hit trouble is when there are two components of the sound revolving around the single LFO. If it's already programmed to operate the pulse width, then you introduce extra vibrato at your peril. The pulse width mod will go haywire.

Three to get ready. Enough of the praise, it's time to moan. There's a chance that I had a rogue sample in for review, but this T-8 would stay in tune for about 15 minutes maximum before it was in need of an autotune. Irritating, but not irredeemable until you realise that the autotune takes 25 seconds. That is a long time when many other synths correct themselves in two or three, or very rarely wander in the first place.

And long before the T-8 had drifted noticeably in pitch, it was already producing dirty, contaminated sounds because the oscillators had strayed enough to unsettle the ear. Rod Argent's assure me that this is not a common characteristic of the T-8, but be on the lookout, nonetheless. £4,000 is what we in the business call 'kerrist...'

But you do get more than just a synthesiser for your four and three noughts. The T-8 carries a 670 note polyphonic sequencer on board, which can not only record your real time riffs, but store all the velocity sensitive expression you've fed into it. Since the VS controls remain editable while the sequence is being played back, you can boost your delicate interpretation, remove it, even reverse it.

There's accommodation for eight separate sequences but sadly, as with nearly all built in sequencers, the editing is non existent. You can't remove notes, add fresh ones, patch sequences together, nor even convert a single riff into a repeating loop without re-recording it.

Four to blow. Finally, after a good two pages of techno-drivel we get on to what actually matters — the sound. Here the T-8 shows a dramatic change not so much in its electronics, but in the minds of its programmers. They've put a vast effort into perfecting a series of piano sounds — I've rarely heard an analogue synth get this close to grands, Rhodes, Wurlies and so forth.

Maybe they thought those would be the best demonstrations of their dynamic keyboard techniques, or perhaps they wanted to take on Yamaha's FM synthesis and prove that analogue could still crack the nuts. Either way there are some fine piano programs loaded in. The main method of analysis appears to involve adding a high harmonic — for example a D will have a B mixed in three octaves further up the scale. It does a passable job of mimicking that metallic twanginess you find in the lower strings of a baby grand.

As before with Prophets, it's the Poly Mod section that's responsible for the warm uncertainty of Sequential's string sounds, the oscillator banks acting as their own individual LFOs. It's also the cause of the slightly inebriated gurgling that authenticates the old Hammond programs.

It's this loose, even undisciplined quality that gives Prophets their warmth and character — the breadth and robustness which defeats FM synthesis, though the latter continues to be the victor with natural percussive tones.


1) The T-8 IS one of the most responsive and expressive polysynths on the market.

2) It allows you control over not one but MANY of the elements that make a synth distinctive, and without ever having to lift your fingers off the keys.

3) The touch sensitivity IS a primary reason for the T-8's existence and not the by-product of spare technology.

4) The sequencer IS useful for short passages to fill in live performances but it is NOT a compositional tool.

5) The memory system is 80 per cent perfect. There are gaps and hiccups which a keyboard at this price should NOT exhibit.

6) The tuning on the review sample was poor. At this price every keyboard that leaves the factory should be faultless.

7) It's expensive, very expensive compared with a DX7, but what price do you put on feeling?


Also featuring gear in this article

Previous Article in this issue

Exchange If Marked

Next article in this issue

Ceiling Tales

One Two Testing - Copyright: IPC Magazines Ltd, Northern & Shell Ltd.


One Two Testing - Feb 1984

Review by Paul Colbert

Previous article in this issue:

> Exchange If Marked

Next article in this issue:

> Ceiling Tales

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