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Siel EX80

Article from Electronic Soundmaker & Computer Music, June 1985

Siel's new expander based on the DK80 synth.

Siel's EX80 expander

Siel's DK80 synth looks like making quite an impact, boasting as it does all the facilities of two touch sensitive Korg Poly 800's in a single package for a mere £699. Now, hot on its heels, comes the keyboard-less Expander version, the EX80, which may turn out to be even better value for money.

This value for money business is a common syndrome among expanders though. Even a machine which doesn 't seem too much of a bargain as a second keyboard suddenly becomes very attractive if it can be used as a slave for an existing MIDI keyboard and has lost a couple of hundred pounds off the price tag. In the case of the EX80 there's one additional hitch though — the fact that it doesn't share the bi-timbric capabilities of the DK80.

As ardent Oxford English Dictionary readers may have spotted, bi-timbric is a new word, invented by SIEL to describe a synth which can produce two completely independent sounds as part of a single patch. The DK80 does this, and can assign the sounds to any range on the keyboard, so you can have split, overlapped or completely layered effects. The EX80, partly perhaps because it doesn't have a keyboard of its own to help make sense of such range definitions, doesn't have the bi-timbric capability.

So what are we left with? As previously mentioned, the DK/EX80 design is similar to the Korg Poly 800's, having complex envelopes and eight digital oscillators but only a single filter shared between them. In fact the SIEL synths, like the Korg, have a second filter too — it's permanently assigned to the white noise output, and so can be useful in defining flute sounds which include just a short chiff of white noise at the start of each note.

A single filter's OK for block chords, solo lines (at which the DK/EX80 design is quite versatile) or wobbly noises. There are lots of great sounds which don't use moving filter effects, but for filter-swept funk sounds, two-handed pieces for synthesised harpsichord or fiddly brass pieces, the DK/EX80 single filter design can be a bind. The single/multi trigger option means either the filter re-triggers on any notes you're already holding when you play new ones, or it doesn't re-trigger at all, leaving you perhaps with a bunch of much flatter sounding notes. Either effect can be pretty annoying.


On the other hand, if you're using the EX80 as an expander for a more powerful synth, this slight lack of articulation in the sound won't matter too much. For instance, a Yamaha DX7 owner may desperately want smoother analogue filter effects than his FM synth can ever provide, and the EX80 could come into its own here. If a SIEL string sound is layered with some DX7 brass, the resulting combination should be powerful enough to put a stop to any arguments about single filters! There are other reasons why this particular combination of synths would be ideal. The DK/EX80 design is touch-sensitive, so the DX7's MIDI velocity output can act to modify its filter, amplifier or both. This facility is simply switched on or off in the EX design — it doesn't have variable level — but the effect is factory set at a very useable depth.

The EX80 would be equally suitable as an expander for other MIDI synths, such as a Juno 106 or SIEL's velocity-sensitive Opera 6 or DK600. Less contrast here, because you're simply layering different analogue sounds, but a cheap way to do it if that's what you want.

The problem is that the EX80 is rather firmly aimed at thd DK80 itself rather than at the wider market. Not as much as is the Yamaha TX7 — that's virtually unusable other than in conjunction with an existing DX7 — but there are one or two pointers which show this principle in action. For instance, when you buy the EX80 it has no power supply — this dual unit comes in an external box with the DK80 and has an unusual output configuration, so it's difficult to whip up a substitute. Additionally, the EX80 could go into a 19" rack, which is the ideal situation for expanders, but the mounting brackets are an optional extra. It does come with an adapter bracket for the DX80's own keyboard stand though!

At least the EX80, unlike some expanders, is capable of editing its own sounds. Parameters are varied by a pair of Up/Down digital access buttons; you have to select a parameter by punching two numbers into the keypad while in Parameter mode, press Enter, then use the Up/Down controls to alter the value. Not something to be tried on stage with seconds to spare, although you could enter one parameter such as filter cutoff for spontaneous variation before starting to play.

The EX80 uses complex envelopes with Attack, Decay, Break Point, Slope and Dynamic functions (plus Damper for an optional VCA footswitch), which allow you to create some very complex moving sounds.

The Detuning section has Coarse and Fine controls — when you put the synth into Double mode, which allows you to play four-voice polyphonically, you can use this to create either interval sounds or thicker textures.

The Detuning section is followed by White Noise Level and the Filter, which has the same complex envelope and dynamic controls as the VCA. The EX80, very commendably, has two LFO's, one with just a triangle wave for oscillator vibrato (why no square wave for trills though?) and one with triangle and square for filter effects. There's a Choice of variable delay on the effects or control from a DK80's modulation button.

The oscillator section has two waveforms — the Sawtooth wave can be switched to 16', 8' or 4' and switched On or Off, and the Square wave has individually mixable levels of 16, 8, 4 and 2 feet — rather like the Poly 800. The Filter has quite conventional Cutoff, Resonance, Keyboard Tracking (Off, Half or Full), Single or Multi Trigger and Envelope Level parameters; there's also a useful chorus and a programmable volume function independent of the master volume control for balancing up the levels of finished sounds.

The EX80 has three non-programmable parameters marked on the front panel. These are Memory Write Enable, if you want to replace the factory sounds; Sequencer Clock, selectable from MIDI, external clock or internal; and MIDI Receive Channel, selectable from 1 -15 or All (Omni Mode).

The back of the EX


The other major facility we haven't covered is the sequencer, which is useful enough on the EX80 but which could be a little gem when applied to external synths. It's a real-time sequencer with a capacity of around 256 notes, automatic looping, optional metronome, variable speed and a selection of clock sources. You can record two patterns with or without a metronome bleep running and can then clock the sequencer internally, from MIDI or from an analogue pulse, sending it to the EX80's own synth voices or to an external synth.

Like the DK80, the EX has a socket for a ROM or RAM cartridge which lets you use an additional 50 programmable or 100 preset memories. The onboard memories are rather limited — 40 preset memories which can be only temporarily edited and a mere 10 user-definable memories. Some of the factory sounds are impressive, but who's interested in presets any more?

As for styling, the EX80 of course matches the DK80 and is light, durable and comfortable to use. And as for sound quality — well, it's highly variable, from brassy to smooth and flutey, from harsh to very subtle with plenty of rich detuned string sounds if you use the chorus. Several of the presets are very clever; some Dual Mode sounds can sweep from left to right as you hold a chord (using headphones or the rear panel stereo outputs panned apart) if you use a patch which fades one set of oscillators down on the left as it fades the other set up on the right.

Synth Chop, Octave Brass, Delayed 5th and Harpsichord are all impressive, and there are plenty of strong solo sounds if your existing synth is better at the chordal stuff. The EX80 would make a great accompaniment to a voiceless portable keyboard such as the Yamaha KX5 or Roland Axis — its velocity sensitivity would be a great asset, and the Reed 4th sound (memory 32) gives a fabulous Jimi Hendrix impression when used with a really dirty fuzz box!

So to sum up, the EX80 is a versatile self-programming expander with a useful sequencer, velocity sensitivity, complex envelope and versatile MIDI functions. It has plenty of smooth or brassy analogue sounds to complement an FM synth, although it's a little lacking in the more metallic effects which oscillator sync or ring modulation would provide.


  • Voices: 8 whole, 4 dual mode.
  • VCO: Sawtooth & square waveforms.
  • Detune: 11 semitones in dual mode
  • Noise level: 0-15
  • VCF Envelope: ADDSSR
  • VCA Envelope: ADDSSR ,
  • LFO1: 4 DCO's Delay 0-15
  • LFO2: 4 VCF Delay 0-15
  • MIDI: Omnimode, or polymode channel 1-16.
  • Sequencer: 2 tracks, real time polyphonic. Max 300 notes.
  • Memories: 40 preset. 10 user definable.
  • Price: £499

The single filter is annoying, but much less so in an expander than in a conventional synth, and once you sort out the power supply and mounting requirements the EX80 can be turned to almost any studio or stage application. The stereo output is a bonus, as are the footswitch functions for the sequencer, patch shift and so on, and above all the EX80 provides good value for money. The onboard memory is a bit limited but getting hold of additional RAM/ROM cartridges should be easy and inexpensive.

As was the case with the Korg Poly 800 and EX800, SIEL's new Expander gets rather more of a thumbs-up than its conventional synth partner. We looked at some of the reasons why this was predictable earlier, but it all comes down to the fact that, for the shop price of the EX80, you're going to get a whole lotta synthesiser.

Price: £499

SIEL UK, (Contact Details).

Also featuring gear in this article

Expand Ability
(EMM Jul 85)

Browse category: Synthesizer Module > Siel

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Performance Power

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Soft Centres

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

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Electronic Soundmaker - Jun 1985

Donated & scanned by: Mike Gorman

Gear in this article:

Synthesizer Module > Siel > EX80

Gear Tags:

Analog Synth

Previous article in this issue:

> Performance Power

Next article in this issue:

> Soft Centres

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