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Quasimidi Polymorph

Sample-based / DSP Modelling Synthesizer
Published January 1999
By Gordon Reid

With several successful dance-oriented synth successes to their name, Quasimidi attempt to buck the trend with their latest offering. The Polymorph does offer plenty to interest the dance fraternity — real-time modulation knobs, and an analogue-style sequencer and user interface — but behind the façade lurks a powerful synth.

Quasimidi Polymorph synthesizer moduleI had an interesting conversation with Matt Bell, SOS's Senior Assistant Editor, a few weeks ago. His side of it went something like this: "Gordon, would you like to review the new Polymorph for us? I know Quasimidi's background is in the dance market, so we weren't sure whether you'd be interested, but there's more to the Polymorph than just that, so perhaps..?" Do you find this as thought-provoking as I do? It suggests that the electronic music industry is divided into two: music for young people (for which read deep trance garage techno old school progressive hardbag — oh, pick an adjective) and music for older people (for which read widdly synthy stuff for boring old farts). To some extent, this is true. You're unlikely to find many TB303s on prog‑rock revival CDs, nor many classical orchestrations for synth on the latest deep trance garage techno old school progressive hardbag (or whatever) releases. But should the electronic instruments themselves be categorised in this way? What would have happened if Moog and ARP had declared that the Minimoog and Odyssey were only to be used for widdly lead lines played by knife‑wielding keyboard wizards? Ooh... it doesn't bear thinking about!

Which brings us back to the Polymorph. On first impressions, it looks like many of the other dance-oriented modules that have hit the market in the last couple of years, with lots of real-time modulation knobs, a grungy sound, and an analogue-style sequencer. Couple this to Quasimidi's dance-biased history so far (just the names of some of their products speak volumes: Technox, Raven, the utterly unequivocal Rave‑O‑Lution 309), and you have what seems like an open-and-shut case, m'lud: the Polymorph is a dance module. But then there's the case for the defence: Quasimidi themselves, who vigorously protest that their latest product is "the first not specifically aimed at dance" and the synth itself, which has waveforms called 'strings' and 'Mellotron'. The jury may need some more time to reconsider...

Physical Impressions

The Polymorph is laid out like a desktop unit, but, in contrast to the Access Virus (with which it will inevitably be compared) its slate-grey control surface lacks nice friendly colours, and its military steel case lacks 'retro' wooden end-pieces. Indeed, with functional grey knobs and dark blue switches that glow a deep purple when selected, it flies in the face of the current trend for all things multi-coloured and splotchy. How very German! The switches — of which there are no fewer than 42 — are positive, and the 44 knobs (though a bit wobbly) are reassuringly smooth in action. A small 2 x 16 character screen, two larger ratcheted knobs, and a headphone socket sensibly placed on the top panel complete the ensemble. So far, so good.

Unfortunately, many of the Polymorph's functions and parameters cannot be accessed directly from the front panel; you often need to use a combination of menus and knobs. Nevertheless, it isn't hard to fathom out the synth itself, and you'll be buzzing around creating new sounds within minutes. The detail of the sequencer is far less intuitive, but once you've got into the Polymorph's guts... that's when the fun starts. And it is fun, believe me.

Brief Specification

  • Polyphony: 8 or 16 voices.
  • Multitimbrality: 4-part with dynamic voice allocation.
  • Modes: Multitimbral, Stack, Rotate, Unison.
  • Oscillators per voice: 3 per voice (polyphony=8) or 2 per voice (polyphony=16).
  • Primary Filters per voice: Switchable 12dB or 24dB/oct low-pass, plus 12dB/oct high-pass.
  • LFOs: 3 per patch.
  • Primary Envelopes: 3 x ADSR per voice.
  • Sequencer: 4-part, each with 4 rows.
  • Patch Memories: 128.
  • Sequencer Memories: 50.
  • Setup memories: 4 banks of 64 each.
  • Audio outputs: 4.
  • Audio inputs: 2.
  • MIDI: In/Out/Thru.

The Synthesizer

The Polymorph is usually eight-note polyphonic (although I'll come back to this point shortly) and its polyphony is dynamically allocated across four virtual 'synthesizers' (ie. the four parts of the Polymorph's four-part multitimbral setup) which you select using the mixer knobs and selectors on the bottom right of the front panel. Patches in each part are set up using the controls across the top half of the front panel, and can contain up to three audio oscillators, but if you expected these to feature the standard saw/square/sine waveforms you'd be wrong. Well... you'd be right, but way short of the mark. There are no less than 128 DSP-generated standard waveforms for oscillator 1, and a further 128 'sync' waveforms if you press the Sync button. Unfortunately, the dedicated sync oscillator is largely inaccessible, and there is no way to tweak its waveform or 1:1 key-tracking rate. This makes many classy sync sounds impossible. Shucks!

Quasimidi Polymorph control knobs.Oscillators 2 and 3 are quite different. These are samples, and it's fun trying to identify the instruments from which they've been copied. OK, so 'Mellotron' isn't too difficult, and I'd put a fair wodge of cash on 'Strings' being a Roland RS202. 'Orchestr' sounds like a close relative of a 3-oscillator Moog, and there even a couple of waves that sound decidedly additive... maybe from a Kawai K5. However, the Polymorph does suffer from an affliction shared with many S&S synthesizers: you can hear the individual multi-samples, and their mapping across the keyboard is all too noticeable at times.

Each oscillator can be coarse- and fine-tuned, and a mixer allows you to add any proportion of each to the voice. However, if you can get away with using just oscillators 1 and 2 (which you often can) you can set OSC3 to zero volume, and the Polymorph then becomes 16-note polyphonic! Strangely, although you can replace OSC3 with an external signal applied to the audio inputs IN1 and IN2, the polyphony will still stay rooted at eight voices, so it's not the third oscillator itself that causes the polyphony restriction. This implies a DSP limitation in the mixer. If the Polymorph was as simple as this, it would still be moderately complex. But it isn't — simple, that is. Take, for example, the oscillator envelope that sweeps the pitch of the sync oscillator applied to OSC1. This offers just attack and decay parameters, but allows you to make many aggressive bleeps and splats (although at slow settings, you can hear the quantised stepping of what is clearly a digitally generated waveform). Two further LCD menu pages also allow you to apply this envelope to the pitch and pulse width of OSC1. But then, if you switch off the 'sync' function, the envelope controls the pitches of all three audio oscillators. Huh?

And what of the LFOs? There are three of these: one each dedicated to Pulse Width Modulation, pitch modulation (which, although there's not a control voltage anywhere in sight, Quasimidi calls VCO-FM) and filter modulation (VCF-MOD). Just to complicate matters, LFO1 also controls the frequency of the 'sync' oscillator when OSC1 is in sync mode. This is a very good feature, and significantly increases the number of sync and wavetable-type sounds available. Oh yes, and LFO3 (the filter one) also modulates the VCA (but the panel doesn't tell you this). Oh well... I'm getting used to the Polymorph's surprises.

Each LFO offers three parameters. The first is its waveform, and you can pick freely between six of these: Sine, Sawtooth, Reverse Sawtooth, Square, 'Trl' (which seems to be another square with lower amplitude), and Random. The Random waveform is especially welcome, because it makes many 'sample & hold' effects possible. The second parameter is the LFO rate. This is particularly useful because, not only can you freely select a rate by ear, you can also synchronise the LFO rates to the Polymorph's internal sequencer (of which more shortly). There are seven sync rates, and these range from 16 LFO periods per bar to one period every four bars. The third parameter is the LFO depth.

The pitch and PWM LFOs also have 'delay' controls (accessible only via the LCD menus) which make delayed vibrato available. Strangely, though, this parameter is not available to the filter/amplifier LFO. On the other hand, the filters themselves have additional menu-only depth controls (with both positive and negative polarities) that influence the amount by which LFO3 affects them.

This brings us neatly to the filters themselves. There are two of these for each of the Polymorph's four 'synthesizers': a resonant low-pass and a resonant high-pass, although neither will self-oscillate. There are 25 menus for these so you have to burrow into the editing system if you want to realise their full power. Annoyingly, you can't immediately select the filter characteristics from the front panel. Sure, you can define whether the low-pass filter has a 12dB/octave rolloff (like the Korg MS20) or 24dB/octave (like Moogs and most ARPs), but that's it. And that's a shame, because there are many other options. For example, the menus allow you to define whether the filters operate in series — which gives a band-pass response — or in parallel, for notching out frequencies. You can also couple the filters' cutoff frequencies, so that they can be swept at a constant difference — a feature I've only previously encountered on the Bob Moog‑designed Crumar Spirit. Other menu-only features include filter overdrive (for adding distortion and 'roughing up' sounds) velocity sensitivity, and, on the low-pass filter only, key tracking, which ranges from zero to 1:1. With dedicated and invertable ADSR envelopes for each filter, the VCF section is a powerful part of the Polymorph. The amplifier, on the other hand, is probably the most orthodox section in the Polymorph. It includes a dedicated ADSR envelope generator, and parameters (in the edit menus only, inevitably) for velocity sensitivity, 'mix' volume, and pan — the last two of which are most important when you use the sequencer.

The elements mentioned so far: envelopes, filters, amplifiers, and LFOs, are of course all standard synth components. But in addition to these, each 'synthesizer' on the Polymorph has access to four effects units. Yes, that's right... each virtual synth has four dedicated insert effects which can be edited and saved within your patches. That's powerful stuff, and if you use all four synths simultaneously you have 16 multitimbral effects units at your command!

The first effect in each 'synth' is pre-determined for you. It's a distortion effect coupled to a further 24dB/octave, resonant low-pass filter. Although Quasimidi claim that this filter self-oscillates, it doesn't actually do this in the purest sense. Sure, at maximum resonance it can whistle like crazy, but it needs a signal to kick it into life. This provides proof that the Polymorph is just a big shiny DSP: unlike their analogue counterparts, digital filters of this sort need to be kicked into life by an external signal, and are incapable of true self-oscillation. The distortion itself is a rasping digital buzz, quite without woomph and warmth. This is, no doubt, why Quasimidi added the filter — to remove the excess high frequencies. In use, the distortion effect is almost unusable for polyphonic sounds, but it's great for creating evil leads and effects. In this context, it has a character that I rather like; uncultured, nasty, and aggressive...

The second effect is a simple 2-band EQ with just four controls: the low band's frequency and gain, and the high band's frequency and gain. Quasimidi don't tell you what type the filters are (I suspect that they are 'shelving' filters, as found on a typical domestic hi-fi), nor do they tell you what gains you are applying at the various settings, nor do they calibrate the frequencies in Hz. Instead, you just get numbers: frequency settings of 5 to 127; and gain setting from -64 to 63. The manual states that the maximum gains are ±12dB, but that's all the help you get.

Next, we come to the two assignable effects units. Both FX1 and FX2 are limited to the production of modulated digital delays (chorus, flanging, and straight delay, to be precise) so there are no true reverbs in the Polymorph. Because the effects are so similar, the parameters are common to all: effect level, delay time, feedback amount, feedback filter (a 6dB/octave filter for high-frequency damping), modulation speed, and modulation intensity. The modulation parameters refer to a pair of dedicated sine-wave oscillators that modulate the delay times of the effects. So, if the parameters are the same, what is the difference between the effect units? Simple: the seven effects in FX1 are monophonic, while the six available in FX2 are stereo and spread the signal across the stereo field — although there is no way to control precisely how FX2 does this. The last part of the Synth section of the Polymorph is the Control menu, which offers seven performance parameters: velocity response curve, sustain on/off, bender sensitivity, modulation wheel assignment and depth, plus aftertouch assignment and depth. Of these, the most interesting are the aftertouch and mod wheel destinations (see separate box). With aftertouch set to, for example, the waveform of OSC1 in its 'sync' mode, you can create some terrific 'tearing' sounds, and PPG-ish wavetable sweeps. It's coarse, uncontrollable, crunchy, and it grates — I love it!

The Sequencer

The other half of the Polymorph is its sequencer, accessed via the controls on the bottom left of the front panel. Quasimidi have designed this to look and feel like the analogue step sequencers of old, but in fact, the Polymorph's sequencer is fairly different. Vintage sequencers are simple, but the Polymorph's can be both arcane and, thanks to the manual, impenetrable. Actually, it's worth mentioning the manual at this point (fortunately, it seems to be a preliminary draft); it's riddled with the kind of Germglish that is good for a laugh, and the section on the sequencer is amazing. It includes the following memorable instruction: "For newcomers in the area of analogue sequencing, we recommend the live album Encore from Tangerine Dream. There you can hear the technique and other manipulation of analogue sequencers." Huh... that's about as useful as suggesting that you can become a film director because you once watched a movie.

The sequencer's fundamentals are, nevertheless, simple. The Polymorph allows you to create four monophonic sequences, accessing the individual steps of the sequences via the eight knobs in the sequencer section. However, each of the four sequences may have up to 16 steps, so you have to use the editing system to select whether you are programming steps 1 - 8 or steps 9 - 16 of a given sequence. Of course, this means that you can only modify one half of the sequence or the other at any one time, and that is a right pain, although you can at least swap from one half to the other in real time while the sequencer is running.

Once you have selected the half you're going to edit, and muted any steps that you wish to omit from the playback sequence, you can select one of four buttons to determine four parameters for each step. The first of these is the most obvious — it's labelled 'pitch' and it makes the knobs respond exactly as expected. The other three buttons are labelled 'Line-1', 'Line-2' and 'Line-3'. If you hold one of these and rotate the Value/Tempo knob, you can select one of 69 parameters — including vital ones such as filter cutoff and portamento — that you can then sequence along with the pitch. This is equivalent to taking the CVs from a four-row analogue sequencer and plugging patch cords into any of 69 CV inputs on a big modular synth. Nice.

Having defined the length of each sequence, defined the step duration in each, chosen the values for the four parameters in every step, and assigned the sequences suitable patches, you can run the sequences forwards, backwards, or have the Polymorph play random steps within them. If you want to create a regular riff, but have it played over a random backing you can do this, too. You can even run sequences of different lengths simultaneously, or choose different lengths for each of the 'lines' within a single sequence. You can also clock the four sequences at different rates, and trigger one from another to create extended patterns. There are even eight sub-sequences within each sequence, which allow you to apply eight different muting sets and transpositions to each of the sequences. Each subset can be selected by either using the buttons found underneath the programming knobs, or using MIDI key numbers. You can even modify these sequences while they are running. This is powerful stuff, and you won't run out of options in a hurry! But you can now see why the Polymorph doesn't feel very analogue. No single vintage sequencer ever came close to offering facilities as complex as these.

In addition to all the above, there are several extra parameters — such as 'groove' amount — buried in the editing system, plus edit pages that allow you to decide whether you can trigger or transpose sequences via MIDI. Then, once everything is running, you can determine how each of the four virtual 'synthesizers' responds to the four sequencer channels. There are four Modes for doing this. 'Multi' is the most useful because each sequence simply plays the patch allocated to it. In contrast, 'Rotate' ignores sequences 2, 3 and 4, and cycles between the four patches on each step of sequence 1. 'Stack' also mutes sequences 2, 3 and 4, and makes every sound play on every note of sequence 1. Finally, Unison mutes 2, 3 and 4, and plays four instances of patch 1 on sequence 1, giving a really 'thick' sound.

Once you have selected the patches and the Mode, you can mix the voices using the four dedicated knobs at the bottom right of the control panel. Indeed, you can even reprogram individual sounds in real time with the sequencers running. Then, once you have created a sequence to taste, you can save everything — voices and patterns — to one of 50 dedicated sequencer memories.

And, before we leave the sequencer behind, don't forget that all the LFOs and many of the delay effects can be linked to the step rate, so you can make patterns far more interesting by modulating and echoing notes in time to the sequence. What's more, you can play along with the sequencer on any of the four voices if you have set up everything correctly. This can be serious fun! As a TV advert says, "if your foot isn't tapping by now, you're already dead..."

MIDI & Other Animals

The final sets of commands live in the 'System menu'. These give you access to necessities such as master transposition and fine-tuning, MIDI assignments, MIDI synchronisation for the sequencer, MIDI input and output filters, and SysEx. This is also where you will find the commands to initialise, save or load individual patches and sequences, save or load complete patch+sequence set-ups, and save or load the whole memory.

The Polymorph transmits all its controls over MIDI. This is an excellent touch because it means that, if you link the internal sequencer to a MIDI sequencer, you can record and replay all manner of knob twiddles and so on (you can record the note data from the sequencer too, but you have to know how to do it first — more on this in a moment). The power of this should not be underestimated. If you want to capture a live performance with all its spontaneous changes in sound and mood, this is how you do it.

Two final menus worthy of note control the allocation of the four parts to the Polymorph's four individual audio outputs, and select between three response characteristics for all the top-panel knobs. The latter of these allows you to stop knobs from 'jumping' between values with potentially unpleasant-sounding results.


If you've read this far (rather than just jumping here after getting through the introduction) you'll have realised that the Polymorph is certainly not a modular version of Quasimidi's Sirius. Neither is it directly equivalent to the Access Virus, the Clavia Nord Lead, or software synths such as Propellerheads' Rebirth. And it's nothing like Roland's JP8080 or Novation's Supernova. So let's ignore fatuous comparisons, and simply judge the instrument on its merits.

The Polymorph is a weird and wonderful mélange of late-1970s analogue concepts, late-1980s digital synthesis, and late-1990s DSP technology. Surprisingly, the blend works well. The DSP-generated sounds on OSC1 can be as aggressive and unpleasant as any other synth I know, and I love OSC2 and OSC3 because these lend an unexpected smoothness and thickness to many of the patches.

Sure, there are some niggles, and a couple of these are irksome. For example, it takes an age to change parameter values with the alpha-wheel, and there's one important feature that isn't even mentioned in the literature. This is the ability to transmit data from the internal sequencer over MIDI, which you may — if you're very lucky — eventually stumble across if you switch LOCAL OFF (it starts transmitting the data then). But I can forgive this sort of thing when an instrument sounds good. From screeching excesses to the best Mellotron imitation I've yet heard, the Polymorph covers a lot of ground, and does so with style. With its 128 patch memories for single sounds, and a further 64 sequencer setups, each of which hold a further four banks of 64 patches, the Polymorph ensures that you'll be discovering new sounds, or preferably programming your own, for a long time to come. And, with an unlabelled bottom plate covering what I hope is an expansion socket, further possibilities may also be revealed in the future.

The factory patches and sequences lean heavily on riffs derived from early 1970s electronica, 1980s electro-pop, and 1990s dance and trance. Many of these are a little too recognisable for comfort, so you should be prepared to spend a fair bit of time modifying patches and writing your own sequences unless you want to sound derivative. Indeed, I think that it would be a shame if the Polymorph was pigeonholed as another 'for electro/dance only' Quasimidi product, because, while it is ideal for Tangerine Dream, Jean-Michel Jarre, and Prodigy impersonations, it's capable of much more than that. Its general synthesis capabilities and excellent MIDI implementation are deserving of a wider audience — perhaps one wanting something a bit different from the same old S&S and physically modelled synths. And that could even include me!

Built-in Processing

The assignable effects are characterised by their delay times, and whether the delay can be synchronised to note values within the sequencer (or not). Here is the complete list:

Flanger0.1 - 13.6--
Space flanger0.2 - 27.2--
Chorus0.4 - 54.4--
Super chorus0.9 - 108.7--
Short delay1.7 - 217.51/16 note
Delay3.4 - 435.01/8 note
Long delay6.8 - 8701/4 note
Stereo flanger0.1 - 13.6--
Stereo flanger0.2 - 27.2--
Stereo chorus0.4 - 54.4--
Stereo chorus0.9 - 108.7--
Stereo delay1.7 - 217.51/16 note 
Pan delay3.4 - 435.01/8 note

The Waveforms

All the simple waveform types are offered — sine, triangle, trapezoid, square, sawtooth, and pulse waves from 100% (square) to 1%. A number of transition stages are provided between each type too.

The complete list of 256 OSC1 waveforms is:

  • Sine (x4).
  • Triangle (x4).
  • Trapezoid (x28).
  • Rectangular (x8).
  • 'R' Sawtooth (x4).
  • Sawtooth (x8).
  • 'M' Sawtooth (x8).
  • Pulse (x64).
  • Sync* (x128): With 'Sync' button pressed.

The samples that make up OSC2 and OSC3 are:

  • SineWave.
  • DeepMoog.
  • DeepBass.
  • Sequenz1.
  • Sequenz2.
  • Sequenz3.
  • Sequenz4.
  • BellWave.
  • ResBass1.
  • ResBass2.
  • WetBass1.
  • WetBass2.
  • Sawtoot1.
  • Sawtoot2.
  • Sawtoot3
  • FatWave1.
  • FatWave2
  • FatWave3.
  • Synced_1.
  • Synced_2.
  • Sync_Up.
  • Orchestr.
  • Strings.
  • Mellotron.
  • ChorWave.
  • Voices.
  • DigiWave.
  • Spectrm1.
  • Spectrm2.
  • Effect.
  • NoiseOSC.

Mod Wheel & Aftertouch Destinations

You can assign each of the mod wheel and aftertouch to one, but only one, of the following destinations at a time. Once assigned, the controllers can affect the destinations by any of four amounts: +50 percent of the full range, -50 percent, +100 percent, and -100 percent.


  • OSC1 Wave.
  • OSC1 Level.
  • OSC2 Detune.
  • OSC2 Level.
  • OSC3 Detune.
  • OSC3 Level.
  • Pitch EG amount.
  • PWM EG amount.
  • PWM rate.
  • PWM depth.
  • FM (vibrato) rate.
  • FM (vibrato) depth.


  • LPF cutoff frequency.
  • LPF resonance amount.
  • HPF cutoff frequency.
  • HPF resonance amount.
  • Filter drive amount.
  • LFO3 rate.
  • LFO3 depth.


  • FX1 level.
  • FX1 feedback.
  • FX1 rate.
  • FX1 depth.
  • FX2 level.
  • FX2 feedback.
  • FX2 rate.
  • FX2 depth.
  • Distortion gain.
  • Distortion filter cutoff frequency.
  • Distortion filter resonance amount.


  • Pan.
Published January 1999