Simon Trask listens to the evolving shape of synthesis as E-mu take sound creation to a new plane...

In recent years very few instruments have challenged the orthodoxy of sample-based synthesis, and of those probably only Korg's Wavestation has achieved mainstream success. Now E-mu, who have made a name for themselves with a series of popular sample playback modules (the Proteus range, Pro/formance, Pro/cussion, Vintage Keys), have dared to try something a bit different.

With Morpheus the company have retained the familiar subtractive synthesis architecture but re-thought the filter section. Like Korg with the Wavestation, they've also concentrated on providing a large number and wide variety of waveforms in the module's wave ROM, without excluding samples altogether. Much of Morpheus will be familiar ground to Proteus and Vintage Keys owners. In fact, despite the inclusion of the new 14-pole filters, two new Function Generators and an onboard effects section, you could be forgiven for thinking that Morpheus was just another E-mu module - it even comes in the same casing as Vintage Keys, though with a modified front-panel layout. Yet it has its own sonic character, and that is down to the preponderance of waveforms and the unique characteristics of the filtering.

It helps to think of a Morpheus filter as a cube, with Filter Frequency Tracking (previously Transform1) being the 'x' axis, Transform^ being the 'y' axis and Morphing being the 'z' axis, or depth (see MT's preview in the November '93 issue for a graphic depiction of this cube). Now think in terms of keyboard tracking, velocity response and note duration respectively - and you have the relationship between the 'cube' and the musical effect of the filters. At each point on the cube is a filter frame, which is a 'snapshot' of the filter parameter settings; Morpheus interpolates between these various frames in response to key, velocity and a host of other note-on and real-time modulation sources, and generates a single, composite filter frame at any given moment.

Morphing, the process which gives Morpheus its name, is the process of continuous interpolation between two filter frames on the 'z' axis. There's a lot more to this than simple filter sweeping, which involves the progression of a single cutoff point from one value to another, as Morpheus's multipole filters allow a much greater degree of control over a sound's frequency content.

Morpheus allows you to assign any one of 198 filter types (including a null filter ie. no filtering) to each of the two oscillators, Primary and Secondary, which make up a Preset. In this way you can quickly create new sounds simply by trying out multiple filter types with a single source sound, or multiple source sounds with a single filter type - either way, it's a hit-or-miss process whose main virtue is speed.

Perhaps sensibly, E-mu don't allow you to create your own filter frames. In fact, the filter parameters are relatively few: type, level, morph offset, filter frequency tracking, filter transform2 and filter reverse on/off (in each case with separate Primary and Secondary values). Tracking, transform2 and morphing can each be put under note-on control from a variety of modulation sources, and morphing, additionally, placed under real-time control.

The modulation matrix is where you shape dynamic control over your sounds; E-mu's modules have always been good in this department, and Morpheus is no exception. The module provides 10 note-on and 10 real-time modulation paths, and allows you to use modulators to modulate other modulators. For instance, you can modulate morphing in real time using one of the Function Generators, and control the Function Generator depth (and therefore the morphing effect) from another modulator eg. assignable MIDI controller A.

The two Function Generators are eight-segment envelopes with level, time (0-4095 milliseconds), shape, conditional jump, conditional value and conditional destination segment values for each segment. An obvious application is to create a simple multi-stage looping envelope and assign it to modulate pitch - allowing you to trigger pitch sequences from a single note. You can also create sophisticated real-time morphing effects by modulating the morphing parameter from one of these Function Generators, or create an echo effect or a multi-stage volume envelope which jumps to segment eight on note release. The possibilities are many, and are well worth exploring if you want to get the most out of Morpheus.

Another feature worth experimenting with is Loop Offset. This allows you to set your own sample-loop start point and duration for each oscillator within a Preset; in this way you can create all manner of new source sounds out of the existing ones - useful enough in itself, but even more so when you combine these new sounds with Morpheus's filtering capabilities.

Turning to the more familiar parameters, Morpheus lets you set the volume, pan position, key range, transpose amount, and coarse and fine tune amounts, and program Alt and Auxilliary AHDSR envelopes, LFOs 1 and 2, double + detune (off, 1-15), Xfade/switch settings, portmento setings, solo mode on/off and priority, sound delay, sound start, sound reverse on/off, non-transpose on/off and loop enable on/off all per oscillator. Other Preset parameters include pitchbend range, pressure amount, controller amounts, velocity curve, keyboard tuning (Equal, Just C, Vallotti, 19-tone, Gamelan and User) and mix select (Main, Sub1, Sub2, FXA and FXB).

With Morpheus, E-mu have also introduced Hyperpresets - essentially an extension of the Preset linking found on other E-mu modules. Up to 16 Presets can be combined in split/layer configurations, allowing you create some complex, or simply big and beefy, composite sounds. Bearing in mind that even single Presets can quickly eat into Morpheus's 32-voice polyphony when you're using both oscillators and some doubling/detuning, you're not likely to be able to use too many Hyperpresets at once - they're perhaps best used individually rather than in a multi-part sequenced context.

Like other E-mu modules, Morpheus can respond on up to 16 MIDI channels at once when set to Multi receive mode, with a single Preset or Hyperpreset assigned to each channel. You then edit a Preset/Hyperpreset 'within' whichever channel is currently selected. MIDImaps, of which there are 16 (plus one stored in the battery backed RAM buffer), allow you to create 'snapshot' assignments of multiple Presets/Hyperpresets, together with volume, pan, mix, MIDI filtering, bank select and program-change map settings for each MIDI channel.

Effects assigned to the two effects processors, FXA and FXB, may be edited globally per MIDImap, adjusted for level and output routings (Main, Sub1, Sub2). You can also opt to route FXB into FXA, either splitting off the FXB signal as a percentage amount or routing it solely through A. FXA cannot, however, be routed through B, which means you can't, for instance, flange, phase or chorus a reverbed signal, which is a pity in my book.

The effects themselves are competent enough, but don't compete with the likes of Korg or Ensoniq for quality, variety or sheer adventurousness. E-mu haven't exactly gone overboard on effects editing either - there's only one reverb parameter, for instance - and there's no dynamic control over effects. It's worth bearing in mind that the Sub1 and Sub2 outputs can be used as effects send/returns or, alternatively, as inputs for routing other instruments via Morpheus's main stereo outs. But you can't route these sounds through the module's effects, nor through its synthesis architecture, as you can with external audio signals on Korg's Wavestation A/D.

Each channel within a MIDImap can be assigned to Main, Sub1, FXA or FXB, or can adopt the Mix assignment of the selected Preset/Hyperpreset. However, you can't set individual effect send levels. Limiting effects assignments to the global, MIDImap level keeps things simple, and is fine for multi-part sequencing, but if you actually want to play single Presets or Hyperpresets with specific effects, then the only way to do it is to call them up as MIDImaps, which limits you to 16 onboard effected sounds.

Perhaps learning a lesson from Korg's experience with the Wavestation, E-mu have ensured that sampled instrumental sounds are present and correct on Morpheus - including the inevitable acoustic grand, a versatile electric piano, some sparkling guitars, an effectively breathy flute and a healthy number and selection of drum and percussion sounds. You could, if you wished, put together a complete demo using just Morpheus.

But overall this is an instrument which is geared towards creative rather than recreative synthesis, and to my mind it's all the better for it. There are some wonderful fat synthbass sounds - Morpheus has a punchy, deep, well-rounded bottom end - together with a plentiful and varied collection of full, rich pad sounds, evocative atmospheres and vibrant leads.

Overall, Morpheus's sound has great presence and energy, and achieves an intriguing and effective combination of digital and analogue, clarity and warmth (though technologically it's a purely digital instrument). Although the module doesn't scream "14-pole morphing filters" from the rooftops, its unique angle in this department does, er, filter through many of the preset sounds.

I'm not sure that morphing is quite as radical in practice as I thought it was going to be (perhaps you'd need to be able to create your own filter frames for that), but equally there's clearly plenty more potential to be wrested from Morpheus through skilled programming. Hopefully, E-mu or a third party will bring out graphically-based editing software, because the module cries out for it; the filter cube concept is itself essentially graphical in nature.

Morpheus is the sort of module that many people will want to add into an existing setup, but it's also credible and appealing for anyone just starting out. I can see it finding a niche for itself in film and TV soundtrack work alongside the Wavestation (the two instruments are actually quite different in character, but have similar strengths), and also appealing to the dance/ambient/industrial fraternity.

Despite its original approach to filtering, Morpheus comes across as an evolutionary rather than a revolutionary instrument - but it's a very appealing evolution.

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