Welcome to No Limit Sound Productions

Company Founded

Our services include Sound Engineering, Audio Post-Production, System Upgrades and Equipment Consulting.
Our mission is to provide excellent quality and service to our customers. We do customized service.

Wednesday, August 28, 2013

Sequential Circuits

Prophet Synthesizers 5 & 10 (Retro)

Reviews : Keyboard
In which Gordon Reid meets a long-time hero and takes a step through the time tunnel to an era when polyphonic synths were still a wish, not a promise.
I met synth designer Dave Smith for the first time a few months ago as he was walking around the San Francisco AES Convention. I glimpsed his name badge while I was talking to one of his associates. "Is that the Dave Smith?" I asked. "Certainly", he said, "Would you like to be introduced?"

Dave Smith is up there for me alongside Keith Emerson and a handful of other pioneers whom I've respected since I was a teenager. As a result, I found myself feeling like a gawky kid as we started talking. But why should a 'mere' designer of sequencers and polyphonic synthesizers (which are, when all's said and done, just specialised computers) evoke such a response from someone old enough and ugly enough to know better? To find out, let's jump in the SOS synthesizer time-machine, and leap back 22 years...


... to a year in which neither of the American keyboard giants of the day offered a true polyphonic synthesizer. Moog had designed the Polymoog around octave-dividing organ technology, and ARP was still playing with various incarnations of 'string' synthesis. Yamaha's CS80 was the successor to the mighty GX1 and as such was the heir to the polyphonic kingdom. But whereas the CS80 had several presets, and allowed you to store four partials in its fledgling memories, it shared a fundamental failing with its only competitor, the Oberheim Four Voice -- it couldn't store all the parameters that defined a patch. Indeed, in 1977, no polysynth could store all the parameters that defined a patch. So it was into this immature market that Sequential Circuits Incorporated (a company that, like Apple Computer, had started out in its founder's garage in California) launched its first keyboard instrument.

Dave Smith and his partner John Bowen had conceived this synth while designing and building a Minimoog programmer and an early digital sequencer. And, by luck or craft, they hit upon a specification that every keyboard player would soon crave -- a five-octave keyboard, genuine polyphony, a powerful polyphonic modulation section, memories that stored every parameter, and a punchy sound reminiscent of the Minimoog itself. 

And The Prophet Shall Speak MIDI
Sequential released the last major revision of the Prophet 5 -- Rev 3.30 -- in 1982, but by 1984 there were rumours about a mythical Rev 3.31 that offered MIDI as standard. These reports exist to this day, but it's more likely that all MIDI'd Prophet 5s have been retrofitted. Maybe one of the reasons for the rumour was the Prophet Remote, a 4-octave sling-on keyboard with a poseurs' neck offering pitch-bend, modulation, volume and filter cutoff controls. You connected this to the synth using a somewhat unwieldy cable that carried serial data -- much as MIDI does today. But the Remote was not a MIDI device, and neither was the Prophet to which you connected it. Sequential produced a MIDI interface that could be retrofitted to Rev 3.2s and Rev 3.3s, although they didn't cater for any instruments earlier than these. If you're desperate for a MIDI'd Prophet, you would be much better off with an upgrade from UK retrofit specialists Kenton Electronics. They will add MIDI to any Prophet 5 from Rev 2.0 onwards, or any Prophet 10, and their board will control many more synthesis functions than does the original Sequential upgrade. Most importantly, it also adds velocity- and aftertouch- sensitivity that can be routed to both the VCF and the VCA.
Kenton Electronics:
+44 (0)181 337 0333.

This synth was the Prophet 10. This looked and sounded exactly like the instrument we now call a Rev 1 Prophet 5, the only difference being that you could play 10 notes simultaneously. Unfortunately, it was hopelessly unreliable, and the build up of heat within the case meant that it was never in tune for more than a few minutes. Apparently, the only solution was a radical one. Smith and Bowen dumped half the electronics, and -- voilà -- the Prophet 10 became the Prophet 5.

Ahh... the Prophet 5. No other name rolls off the tongue as smoothly, nor excites the younger generation of analogue anoraks as much. Indeed, we wrinklies remember when Sequential first burst upon the music scene, redolent with the promise of five programmable Minimoogs in a single polyphonic keyboard. Oh, how we lusted when we glimpsed its beautiful koa wood case, expensive-looking hardware, and well-designed control surface. (Get a grip, man -- Ed.)

OK, so the earliest 5s were stripped-out versions of the failed 10s, and they remained incredibly unreliable, requiring further modifications to make them usable. Nevertheless, they were beautiful instruments that felt and sounded absolutely 'right'. But let's get one thing clear. The Prophet was not a polyphonic Minimoog, and its voice architecture was much more closely related to that of the ARP Odyssey than it was to any Moog of the time. The twin oscillators per voice, dedicated LFO, pulse-width modulation, cross modulation, oscillator sync, ADSR envelope generators, and conventional CV and Gate interfaces (which controlled the fifth voice only) were all features found on the Odyssey, but not on the Minimoog. Nevertheless, the Prophet sounded much warmer and fatter than the ARP, so the myth flourished.


Sequential only built 182 Rev 1s, and few of these have survived 21 years. Hand-assembled, and then rushed out the door to generate desperately needed cashflow, they proved too fragile for life in the fast 

The Emu Prophet 5?
Much of the credit for the early Prophets' sound -- which is instantly recognisable, even today -- lies with the SSM oscillators used. These were developed for Solid State Microtechnologies by Emu which, at the time, was known only as a manufacturer of obscure and esoteric modular synthesizers. But Emu's founders and engineers, Dave Rossum and Scott Wedge, were far from locked into the analogue world. Indeed, as early as 1973 they had developed a digitally-scanned keyboard architecture, and it was this, together with the SSM chips, that helped make the Prophet possible. Later, Rossum and Wedge were to launch the Emulator I, the world's first 'affordable' sampler. The rest, as they say, is history.
lane. So the next incarnation, the unsurprisingly named Rev 2, was by necessity a more robust beast.
Sequential substantially redesigned the Rev 2, made a few cosmetic changes, and added cassette storage for its patch memories. Unfortunately, they also replaced the beautiful koa case with a less attractive walnut one. Eventually, there were to be three sub-revisions of the model (2.0, 2.1, and 2.2), and Sequential built more than 1,000 of these. For many aficionados these are the ones to have, being somewhat more reliable, yet retaining most of the qualities of the earliest models. Unfortunately, the same cannot be said of the Rev 3s.

In 1980, the Prophet 5 was undoubtedly the synth to own. Sequential's name and reputation were unassailable, but their instruments were still unstable and, with fewer than 1300 yet shipped, hard to obtain. The reason for the Prophet's sonic instabilities was, to some extent, explained by the inherent deficiencies of the SSM oscillators used. And the reason for its rarity was, to a very great extent, explained by the inherent deficiencies of the manufacturer of those SSM oscillators. So Sequential decided to jump ship and switch to Curtis (CEM) chips. This entailed another, much more thorough, redesign that included the power supply, envelopes, DACs and VCAs, so it is perhaps a compliment to the company that the sound of the instrument escaped almost unscathed.

Unfortunately, the 'almost' is important. While the quirkiness of the SSMs undoubtedly contributed to the richness of the sound, some decidedly dodgy engineering in other areas contributed to the highly 'organic' nature of the early Prophets. On Rev 3s, some of the bite had gone, leaving an instrument that remained impressive and pleasant to play, but was slightly cold and featureless by comparison to earlier models.


Meanwhile, reports had been leaking out that Sequential Circuits was designing a touch-sensitive synthesizer. This created a great deal of interest because, except for the ghastly Polymoog, Yamaha's unwieldy CS80, and hyper-expensive rarities like Yamaha's GX1, there were no polyphonic synthesizers that you could play expressively like a piano or a pressure-sensitive monosynth. Yet, when Sequential unveiled their new baby, it proved to be the monstrous twin-manual -- and completely insensitive -- Prophet 10.

Sequential built three prototypes of the larger Prophet 10 using SSM chips, but before production began the jinx struck again, and the company had to change everything to its newer Curtis-based architecture. So, contrary to some rumours, all the Prophet 10s shipped to customers were CEM-based, and offered the slightly less gritty sound of the Rev 3 Prophet 5s.

Despite that, the 10 was special. More than simply two Prophet 5s in a box, it was a sonic monster that could allocate its 10 voices in several modes ranging from a two-oscillator-per-note 10-voice synth, to a monosynth with 20 analogue oscillators under a single key. It was easy to program powerful analogue pads and luscious, deep strings, and if you wanted screaming leads, chunky bass patches, distorted filters, tortured resonance, and a doubled unison mode that made speakers spontaneously ignite, a Prophet 10 stood head and shoulders above almost every other synthesizer. You could also use the 10 as two entirely independent synthesizers playing, for example, a unison lead on the upper manual, with a powerful polyphonic accompaniment on the lower. OK, so the ability to perform multiple duties is meat and drink to modern multitimbral instruments, but the 10 still scores in the depth and the power that it can create.

But not everything in the Prophet 10's garden was rosy. The first batch of 10s (of which there were only 300 or so, curiously called Rev 0s) incorporated a 'wafer' drive for backing up patches and storing any data recorded on the synth's internal six-track sequencer. These drives, made by Exatron, were plagued by failures and, even when they worked, the backups were frequently incompatible from machine to machine. So, when Exatron was taken over in 1982, Sequential swapped to a Braemer micro-cassette drive. This was far more reliable, and stored 10,200 sequencer events compared to the earlier unit's 2500. Sadly, the Exatron and Braemer drives were completely incompatible, so there was no way to transfer information from older synths to newer ones. Oops!

Rev 0s also suffered from memory problems, and most were recalled to the factory for a modification 

Which Prophet?
A pristine Prophet 5 will set you back anything from £500 to £1200 depending upon the revision, and a mint Prophet 10 will cost up to £2000. These prices are crazy, if only because, contrary to anorak mythology, the sound of a Prophet can be emulated by any number of modern instruments. But the craze for analogue synths sets its own prices, and the reverence in which the Prophets are held far outstrips their tangible values. If you absolutely must have one, remember the following. The best sound undoubtedly comes from Rev 1 Prophet 5s. But these are excruciatingly rare, hopelessly unreliable, and almost nobody will fix one if it goes wrong.
Rev 2s sound almost as good, are slightly more reliable, and can be MIDI'd. Unfortunately, few service centres will repair them, and many parts are now unobtainable. Don't pay too much for a Rev 2. The sound is worth it, but the risk isn't.
If you're after reliability and the reassurance that somebody will at least try to repair it if it goes wrong, your only option is a Rev 3 Prophet 5, preferably a 3.3 because of the extra 80 memories. But beware the slightly less engaging sound. Pay no more than £700 for the 40 memories of a 3.1 or 3.2, but be prepared to cough up about £1,000 for a perfect 3.3 with MIDI.
Alternatively, you can dig deep for a twin-manual Prophet 10 -- allocate all 20 oscillators to a single note, then you'll be able to get rid of your neighbours, no problem.
Under no circumstances should you be tempted to buy one of the few remaining single-manual Prophet 10s. Unless you're in business as a synth museum, that is!
(the so-called 'ugly' mod) that stopped them from dumping all your laboriously perfected patches into the synthesizer ether. But once everything was sorted out, the Rev 1 Prophet 10 was probably the synth that Sequential had always hoped it would be.
Unfortunately, 1982 was four years too late to launch another analogue behemoth and, at around £6000, the 10 was far too expensive, particularly since it offered neither velocity nor aftertouch sensitivity, and boasted a mere 64 patch memories. In contrast, the Prophet 5's reputation swept all before it and, with a production run of nearly 6000 units, the CEM-based Rev 3s were to become the most successful synths ever produced by Sequential. Let's be fair, Rev 3s had their good points. Perhaps the most useful of these was the instant editing feature introduced on Rev 3.1. This meant if you turned a knob it immediately became active at its visible value. (On earlier versions you had to press an Edit button, and then add to or subtract from the value in memory.) Another benefit was micro-tuning which, while common today, was exceedingly rare in 1982. And yet another considerable bonus was, on Rev 3.3s, a leap in memory capacity from 40 to 120 patches.


Although the Prophet 5s and Prophet 10s incorporated Z80 microprocessors, they are nevertheless regarded as 'true' analogue synths. This is because their microprocessors were limited to housekeeping duties such as scanning the keyboard(s) and storing patches. But Sequential's next roll of the dice was a synth that used both analogue and digital circuitry (an analogue/digital hybrid) to produce its sound. This was the Prophet 600.

The 600 was a clear descendent of the Prophet 5 because, although Sequential used cheaper knobs and switches, the newcomer retained the general layout of its predecessor. The 600 was also the world's first MIDI synthesizer and, as such, was to help change music composition and performance for ever. But there was a downside. The 600's digitally generated envelopes were slower and less punchy than the analogue circuits of the 5 and 10, and its controls -- under certain conditions -- were audibly quantised. Furthermore, at £1650, the 600 was almost as expensive as a 5, and significantly more expensive than the new, all-conquering, Japanese wondersynth, the Yamaha DX7. As a final nail in its coffin, Prophet 600s proved to be unreliable. Changes in temperature and humidity, or indeed rises in the price of beer, were likely to send a 600 off into the further reaches of Eastern atonal music, If one got really excited it could even jump out of its patch altogether. All would be returned to normal by pressing the 'Preset' button a couple of times -- but if you didn't have a hand free, things could get decidedly embarrassing up on stage!

Later in 1983, Sequential released another analogue/digital hybrid, the Prophet T8. Internally, this was a close relative of the 600, but externally it looked far more akin to Sequential's earlier instruments. And, if one ignored the instrument's extra features, it sounded somewhat like a Prophet 10. However, unlike its predecessors, the T8 boasted a piano-weighted keyboard that offered velocity sensitivity, release velocity sensitivity, and polyphonic aftertouch. With two optical sensors to determine key velocity, and individual pressure sensors for each key, this was a masterpiece of engineering that allowed you to control your sounds in ways no other synth could emulate. (Indeed, when New England Digital decided to upgrade their £20,000 Synclavier to offer touch sensitivity, it was to the T8's keyboard that they turned.) In addition to this, the T8's MIDI spec was outstanding, with full control over polyphonic aftertouch and micro-tuning. Remarkable in 1983, some of the T8's features would be welcome on synthesizers in 1999.

How Much?
Below is a list of the most influential VCO-based synths of the late'70s and early '80s. Like the Prophet 5 and Prophet 10, each offers two or three oscillators per voice, but none has velocity- or aftertouch-sensitivity.
Model Polyphony Original Price 2nd-hand Price 2nd-hand rip-off
Moog Memorymoog
/Memorymoog +
6 £3100 £600 £1200
Oberheim OBX * 4, 6 or 8 £2595 £300 £600
Oberheim OBXa * 4, 6 or 8 £3495 £400 £800
Oberheim OB8 8 £2,995 £500 £1000
Roland Jupiter 8/
Jupiter 8A
8 £3995 £400 £1000
SCI Prophet 5 5 £3395 £500 £1000
SCI Prophet 10 10 £5600 £750 £2000
* Price shown for eight-voice versions.


By the end of 1983, Sequential boasted the most impressive line up of analogue synthesizers in the world. The Prophet 5 was still in demand, and the 10 was, if not a commercial success, an impressive flagship for the range. OK, the 600 was a bit dodgy, but the impressive T8 offered facilities that you couldn't get anywhere else. So Sequential started to make buckets of money and became one of the biggest music
"...if you wanted screaming leads, chunky bass patches, distorted filters, tortured resonance, and a doubled unison mode that made speakers spontaneously ignite, a Prophet 10 stood head and shoulders above almost every other synthesizer."
corporations in the world. Right? Well, no. Within a few months, all four instruments were regarded as over-priced, and designed around desperately unfashionable technology. As a result, few people noticed when, in 1984 Sequential ceased production of the Prophet 5 and the Prophet 10. The Prophet 600 was buried the following year, and the T8 followed in 1986. 

The company never regained the market leadership it had enjoyed from 1978 to 1982. Perhaps it should have ditched the 10 after its abortive first incarnation. Perhaps it should have concentrated on the technical innovations that would continue to keep it at the forefront of music technology. But then again, the world's first multitimbral synth, the Sequential SixTrak, was no great hit, and addressing the home computer market during its slump in 1985 was a big mistake, so the MultiTrak and the Max also bombed. When the company entered the world of sampling in 1985, it was already in trouble. The 12-bit Prophet 2000 and its modular sibling the 2002 were well received, but the functionally similar and much cheaper Korg DSS1 synth/sampler seriously dented their sales.

So maybe Sequential was always doomed to follow Moog and ARP into oblivion. Breathing space appeared in 1986 with the excellent Prophet VS, an instrument that yet again introduced a new concept and a new sound generation system -- Vector Synthesis -- to the keyboard world. But it was too little, too late. The company's final products, the Studio 440 and the 16-bit Prophet 3000 sampler, barely made it into production, and SCI closed its doors late in 1987. It was the end of a dynasty.

Tony Banks On Prophets Large And Small
I interviewed Tony Banks of Genesis in 1994, and we spent a considerable amount of time discussing Prophets. "The Prophet 5 had a real roundness to its sound and was, as far as I was concerned, the first polysynth that sounded really musical. So I used one for recording our album Abacab in 1981. The Prophet 10 was just an extension of that. For example, the track 'Man on the Corner' has two tracks of Prophet 5 that were recorded separately in the studio. These were factory voices, simply because Phil [collins] wrote the track on an un-reprogrammed Prophet 5, and I was able to reproduce it live using the Prophet 10 by allocating the different patches to the two keyboards.
"At the time, my live setup was limited to just four keyboards. The Prophet 10 was used for synthesizer and organ voices, while the solos were played on an ARP Quadra which had replaced my earlier ARP 2600 monosynth. I also used a Yamaha CP70B electric grand piano and a Roland VP330 Vocoder Plus that had been introduced to recreate the choral and strings voices of my Mellotron. Actually, there was a fifth instrument -- a Prophet 5 -- on the other side of the stage, and I used this for playing 'Who Done It'. This was a tune written around torturing the Prophet by stepping through the programs while playing the riff to the song. This did some very strange things, producing some unpleasant sounds and even changing key, but I liked it. Furthermore, it was consistent, so I could reproduce the effect live. It sounded like I was playing many more instruments than just the single Prophet 5.
"My favourite use for the Prophet 10 was to produce big organ sounds. Allocating four oscillators to each key meant that I could imitate four drawbars to build genuine organ sounds. It was the first time that I successfully got rid of my Hammond for live work. I even found the 10 to be reliable except for the tape-based voice storage. Consequently, I occasionally had to reprogram it, and we carried a spare machine for emergencies. Unfortunately, this didn't sound the same as my first-choice instrument. In particular, the tuning was different, and this was critical on, for example, 'Dodo' which sounded quite different on the spare synth.
"The best sounds on our next album, Genesis (1983) were also from the Prophet 10. The big chords -- organ-like but with 'stringiness' -- on 'Mama' were Prophet sounds, as was the low drone that was created using Unison mode. At that time I also had a Yamaha CS80 and a touch-sensitive Prophet T8, but by then other sounds and types of synthesis were coming along, and as far as I was concerned, the emergence of digital synthesis and sampling on the Emulator I ended the era of the big analogue polysynth.
"Nevertheless, I liked the Prophet era of instruments because you could home in and tweak the sounds so easily. In fact, as soon as I received my Prophet 10, I dumped the factory sounds and started programming the instrument again. I miss this immediacy with modern sample-based instruments such as the Roland JD800 which I used on We Can't Dance (1992). On these you have to choose the partial you want to edit, adjust that, then choose another. The D50 also suffered from this, and the Yamaha DX7 was the worst. Sometimes this isn't too much of a problem. For example, the Korg Wavestation has some great factory sounds (such as the one I used on 'Fading Lights'), but I would still love modern instruments to have arrays of knobs like the Prophets.
"I suppose that the Prophet 10 was the peak of pre-digital big analogue synthesis. But keyboards tend to improve and, unlike guitars, where a 1950s instrument can be superior to a 1990s model, you don't lose too much if you move on."


In 1988, Yamaha bought the rights and assets of SCI, and these rights included the employment contracts of many of the company's development team, including Dave Smith himself. It wasn't a happy marriage, and they worked together for less than year, but in that time Yamaha developed the SY22, a vector synthesizer that proved to be a direct descendent of the Prophet VS.

Then, in 1989, the team moved to Korg, where they designed the now-classic Wavestations. These were also vector-synthesis instruments and, despite an arcane programming system, were far more powerful than the SY22, and sounded significantly better. But despite Smith's achievements in the late '80s and early '90s, many people believe that he never surpassed the Prophet 5 and the Prophet 10.


Which brings me back to last year's AES Convention. When I met Dave Smith at the AES, he wanted to talk about his latest developments and his recent audio software projects. I, on the other hand, wanted to chat about stuff he did nearly 20 years ago. Indeed, I childishly tried to impress by telling him that I had just bought a second Prophet 10. He seemed a bit surprised, until I joked that, since the serial numbers were different, I felt that I ought to have both. Then he smiled. If you ever have the chance to own one, so will you.

No comments:

Post a Comment