JEN Synthtone SX1000 (Retro)

Monosynth

Reviews : Keyboard

Some cheap monosynths from the '70s and '80s are now highly regarded and hugely expensive second-hand buys. Not so the Jen SX1000 which, says Gordon Reid, is an unjustly neglected nugget of synth history.

Fashion can be a very destructive force, making you do all manner of things you would prefer not to. And, as in real life, the world of synthesizers has its fair share of 'what's in?' and 'what's out?' issues. Did I ever tell you the true story of the three cased TB303s I turned down for $50 each in Nashville one summer? At the time, I could not imagine why anybody would want one of those horrid little boxes, let alone three. (And, to be honest, I still can't -- but that's another story.) In contrast, while I don't imagine that the subject of this month's retro will be responsible for a whole musical genre, I can (and do) contend that it's a synth that deserves to be appreciated more than it is at present. It's the small, but beautifully formed, Jen SX1000.

Mention the SX1000 to any serious vintage synth anorak, and you'll be met with much laughter. But why the little Jen should have become so uniformly derided escapes me. Even in the digitally dominated days of 1985, Julian Colbeck described it as a "fine box for mucking around with, or for learning about synthesis" and "a first-class first-time buy". On its release in 1977 this might have been justified, at least in part, by its super-low recommended price of just £210. Indeed, this had dropped to £159 or thereabouts by the time that the SX1000 was discontinued in 1982, and its street price was often considerably less. But it would be unfair to suggest that the only reason for liking the SX1000 was its price. It was also a fine little synth.

Cheap And Cheerful

At first sight, the SX1000 appeared very basic. And, on second and third sights, nothing changed. It had a short, 37-note C-to-C keyboard, a mere 24 programming controls, no CV and Gate inputs or outputs, and no pitch-bend or modulation wheels. Indeed, it was entirely without frills: no velocity sensitivity, no pressure sensitivity, no nothing!

Voice Cards 1978-Style In 1978 the idea of a 'voice card' was very different from that we now enjoy in the late '90s. The SX1000 came with a handful of such cards which were, literally, pieces of card that you laid on the control panel of the synth so that the knobs poked through in the appropriate places. Two patches (or 'voices') were laid out on each card, one marked in red, the other in blue. So, for example, you would find Violin and Cello on one card, with Human Voice 1 and Human Voice 2 on another. Others included Piano, Flute, Hammond Organ 1, Hammond Organ 2, Brass 1 and Brass 2, the aptly named 'Synthesizer', and Electronic Drum. Of course, none of these but the last pair sounded remotely like the instruments named, but rather (like the patch charts that accompanied many other synths' instruction manuals) evoked the sense of the sounds described. There were even patch blanks, on which you could 'memorise' your own sounds by scribbling. Primitive it most certainly was, but coming with a synth whose price barely made it into three figures, I reckon that it was excellent value. Were Jen still around today, I would say to them 'bravo!'

The sound was generated by a single oscillator, described on the control panel and the voice cards (see box below) asa VCO, but by previous writers as a DCO. The truth is that it was a strange halfway house that was neither entirely voltage-controlled nor digitally controlled. It worked something like this... The oscillator itself was a high-frequency square-wave generator, stabilised by a digital circuit. So far, so DCO. The output from this was passed to a large 40-pin chip (which would now be almost impossible to replace) which shaped the wave into a wider selection of waveforms and divided it down to the standard range of audio frequencies. But what about the 'Fine Tune' control on the top panel? This, indeed, was a standard voltage control that affected the frequency of the high-frequency oscillator. The range of its affect was rather small but it was, nonetheless, a voltage control.

Clearly, the SX1000 was a hybrid, and it suggests that, in 1978, Jen had a technological lead over much of the rest of the synthesizer industry. After all, it was to be another four years before Roland released the Juno 6, the instrument that is often credited as being the first DCO-based synth.

Whether you consider the oscillator to be voltage- or digitally-controlled, it was nonetheless well specified. It offered sawtooth, square and pulse waveforms (the last of these featuring pulse width variable between 5 percent and 50 percent, plus pulse-width modulation) pitches from 32' to 4', portamento, and a 'Level' control that allowed you to determine how much signal was passed to the rest of the signal chain. There was also an independent noise generator, with white and pink characteristics, and its own Level control.

The output from these passed to a low-pass VCF. This had the usual complement of frequency and resonance knobs, and a dedicated ADSR envelope generator with envelope 'Level' control. The filter sounded like a 12dB/octave design (I have never seen any proof of this, but other players agree), and would self-oscillate at high resonance settings. Finally, as far as the main signal path went, the VCA offered a second ADSR, and a final 'Output Volume' control. (The second envelope was a very good attribute for the price, because almost all cheap synths of the time used a single ADSR generator for both the amplifier and the filter. Indeed, even the highly regarded SH101 did so some five years later, so the Jen's second ADSR was not an insignificant bonus.)

Modulation came from a single LFO, and it is here that the SX1000 was probably at its weakest. With a single waveform, and just a single knob for 'speed', you could hardly have described it as over-endowed. Furthermore, the LFO was rooted firmly at sub-sonic speeds, so no complex FM-type modulations were possible. Moreover, it had just three destinations -- PWM, the VCO and the VCF -- so vibrato and growl/wah were available, but tremolo was not.
In a synth as basic as this there were, of course, many other omissions and weaknesses. For example, while I had no problem with the SX1000 using lowest-note priority (most synths of the time were designed like this) I found its permanent 'multi-triggering' a bit uncomfortable. Multi-triggering meant that every note you played was fully articulated according to the filter and amplifier envelopes, so you couldn't slur notes by playing legato. Some better-equipped instruments of the era offered multi-triggering as an option, but I can't remember many that relied upon it as the sole mode of operation.
Other weaknesses lay, almost inevitably, in the filter. Not in the sense of now-hackneyed and often poorly understood phrases such as 'fat like a Minimoog' or 'squelchy like a 303', but in its keyboard tracking. From top to bottom of the three-octave keyboard, the filter only tracked through a little more than a single octave, and no amount of adjustment of the internal circuit trimmers seemed to extend this. (Hint: don't try this at home. Internal adjustment should only be carried out by unqualified idiots who are prepared to accidentally disable the Filter Release knob while poking around ignorantly.)

"...the SX1000 was completely knobby, it had a wooden chassis, a pressed steel control panel, and it even had nicely veneered wooden end cheeks. What more could an analogue anorak want?"

The Jen's tracking range was equivalent to the '1/3' setting on a Minimoog, and adequate for ensuring that high notes were brighter than low ones, but it precluded any clever use of self-oscillation as a second oscillator, or for tracking the harmonics of the VCO. Furthermore, the bottom end disappeared very quickly as you increased the resonance, resulting in a fairly gutless sound at any setting much above zero.
My final gripe with the SX1000 lay in its knobs. These had little metal caps that colour-coded the instrument's functions -- red for the oscillator, silver for the filter, blue for the envelopes, and so on -- which, you might think, was a damn good idea. I agree. But, unfortunately, they tended to fall off, leaving half the knobs looking very attractive, and the other half... well, tatty, with a blob of dried-up glue on the top. Shame!

Getting Communicative The SX1000's lack of CV and Gate inputs is quite a limitation in today's musical climate, especially because the SX1000 would be an ideal synth for simple arpeggios. Fortunately, there is a solution in the form of a retrofit from Kenton Electronics. You can order these in either Hz/V or the technologically more expensive V/Oct forms, and each kit offers pitch CV, filter CV and Gate inputs. You can buy them in kit form for approximately £50 and £70 respectively, or have Kenton fit them for you. But hang on a minute... the SX1000's strange, hybrid oscillator only accepts voltage control over a very small range, so how does Kenton's upgrade allow you to play the instrument over a usable range? The answer is both simple and dramatic. The Kenton retrofit not only adds the appropriate control circuitry, but replaces the oscillator itself! The replacement is another high-frequency square wave oscillator, but this time voltage-controlled. The output from this is waveshaped and divided down by the Jen's own circuitry to ensure that the sound stays the same as before. Ingenious! Kenton Electronics +44 (0)20 8337 0333.

But despite its limited architecture and these weaknesses, the SX1000 scored well in the department that matters most: the sound. While I realise that this was never a popular view, I found the little Jen to be a very clean instrument, with a flexible and inviting sound, reminiscent of a Korg 700, but with greater flexibility. Indeed, the SX1000 scored over the 700 because all its thickest sounds came from its flexible PWM -- which the Korg only offered as 'Chorus I' and 'Chorus II' settings -- and user-definable pulse-width, which the Korg also lacks. It is surprising, therefore, that the more limited 700 has since become so widely appreciated, while the Jen has not.

Part of the reason for this is, perhaps, to be found in the company that the SX1000 kept. Whereas the Korg 700 later grew a second oscillator to become the 700S, then almost doubled in power again to give birth to the Korg 800DV, the Jen had no such illustrious siblings. Its sole partner was the particularly unpleasant SX2000 -- a semi-preset synth designed, like the Roland SH2000 and Korg 900PS, as something to sit on top of a home organ. However, unlike its competitors, or the wonderful ARP ProSoloist, it had no touch-sensitivity. Oh yes, and despite its filter circuit being comparable in some ways to those of the TB303 and EMS VCS3, it sounded horrible.

Indeed, throughout its seven-year dabble with the keyboard industry, Jen made only three other instruments: a ghastly electronic piano, an unremarkable string synthesizer, and the polyphonic Synx 508. The last of these is notable for being one of the few truly horrible polysynths. With all manner of idiosyncrasies (that's a polite way of saying design faults and elementary cockups) and the weakest sound you've ever heard emanate from a large, polyphonic keyboard, it was all but unusable, and to be avoided at all costs.

But what might have happened had the SX1000 been the Korg 750 or the Roland SH4? Or even one of the smaller and less heavily endowed ARPs or Moogs? It would still have lacked the sonic power and kudos of its stable-mates, but I believe that it might now have been 'rediscovered' in the current fad for all things analogue, not as a replacement for more powerful synths, but as a complement to them. Look at it like this: the SX1000 was completely knobby, it had a wooden chassis, a pressed steel control panel, and it even had nicely veneered wooden end cheeks. What more could an analogue anorak want?

The Synt-O-Rama It's possible that Jen entered the synthesizer business five years before the arrival of the SX1000 and SX2000. I have found one reference (in Peter Forrest's excellent A-Z of Analogue Synthesizers) to a thing called the Jen 'Synt-O-Rama', which may or may not have made a brief appearance in 1973. But, despite being an enthusiastic wannabe keyboard player at the time, I can't remember any mention of it, nor can I find anything on the internet to confirm its existence. Does anybody in SOS-land know more?

But such speculation is worthless. Following their brief, and very minor, flirtation with the synth world in the late '70s and early '80s, Jen followed the same path as the other Italian keyboard manufacturers of the time. Despite a couple of now-forgotten prototypes shown briefly in 1984, the Synx 508 was the company's last instrument, and its brief production run proved to be Jen's swan-song.

So there it is: the SX1000 Synthetone -- gone, largely forgotten, and lamented by almost nobody. But, sitting close to my revered Moogs and ARPs, I've got two of them. They cost me a total of £70 for the pair, and you will still find one for £50 or so if you shop around. At that price, you should try it. As Julian said a decade and a half ago, it was, and remains, a "fine box for mucking around with". (Lousy grammar, good sentiment.) Indeed, if you stick one through a decent reverb or multi-effects unit, you may even find that it's a bit more than that. Go on... ignore fashion and risk becoming a trend-setter.

Published in SOS November 1999