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Dave Smith Mono Evolver Keyboard

Analogue & Digital Synthesizer
Published December 2006
By Paul Nagle

Dave Smith MEK

Pushing at the boundaries of synthesis, as ever, Dave Smith's Evolver range continues to evolve...

The top-of-the-range Poly Evolver Keyboard from Dave Smith Instruments is impressive indeed but, as is so often the case, it comes with an impressive price tag as well! Wouldn't it be great if there was a more affordable version: one that offered the single-voice architecture of the original desktop machine, but with a keyboard and a full set of controls?

Dave Smith has been around since before the dawn of MIDI, so I won't restate his credentials here, but you can take it as read he's not going to miss an opening like that. Enter the Mono Evolver Keyboard: a monophonic synthesizer perfectly proportioned for solo or bass duties, and a lot more besides. Could this be the best Evolver yet?

Got Wood

The Mono Evolver Keyboard (MEK) has certainly come a long way from the video-cassette-sized box we reviewed back in February 2003. Framed by two sturdy wooden end-cheeks and peppered with attractive red and blue LEDs, the metal-bodied MEK invokes a feeling of rightness from the outset. Three octaves is an ideal size for a solo synthesizer keyboard and with both velocity and aftertouch response, the result is highly playable, expressive and compact. One slight irritant was the physical 'clunking' noise made by a couple of the keys when in action.

If, like me, you often work in darkness, you will be struck at once by those blue LEDs, which can be dazzlingly bright if viewed straight-on. Their output has been dimmed in comparison to those of the Poly Evolver Keyboard, but is still a bit much for my taste. Of course, you may consider the light show well worth it once you see those four LFO LEDs shimmering, or the step sequencer flashing along at full pelt.

On the review model, a sticker beneath the mod wheel and pitch-bender offers handy hints about the factory sound banks and suggests you should play in stereo and use the wheels and aftertouch. This advice is probably intended for music shops and trade shows, so hopefully the sticker isn't present on all units, or won't leave a dirty mark when peeled off.

The power supply is external and, worse, is connected via a naggingly short cable. On the plus side, it is about as neat and unobtrusive as any adaptor I've seen — so if you have to have one, this is as bearable as it gets. Without an internal transformer, the whole synth weighs in at around 13lbs.

Addressing one of the shortcomings of the original desktop model (and with the exception of the power adaptor, this model addresses them all), there is now a headphone socket. There are further add-ons in the form of a damper pedal input and two control pedal inputs, so you can put your feet to good use. And, in addition to the usual MIDI trio, a second MIDI output is provided to make connections simpler when stacking Evolver voices (see the 'Evolver Family' box). Twin audio inputs and outputs are present as ever, but no digital I/O.

To keep down costs, the original table-top model employed a simple three-character display combined with a matrix-style access method. Improving on this considerably, the MEK features a standard LCD plus numerous rotary encoders and buttons.

Compromises are few, although some controls are shared. For example, the sequencer shares its encoders with the VCF and VCA sections; when the Seq Edit button is active, these encoders are used to tweak the sequencer's individual steps instead of performing their normal duties. Similarly, the four oscillators and four LFOs require only 12 encoders in total, plus a series of selection switches. This is a reasonable trade-off in my opinion — imagine the size of the panel needed to house dedicated controls for all!

To an extent, the use of rotary encoders renders sharing of controls fairly painless. However, I share some of Steve Howell's misgivings, as expressed in his review of the Poly Evolver Keyboard. There is no meaningful feedback from the encoders, so even after a lengthy editing session, their position is always unrelated to the parameter value. Also, it may require multiple turns to sweep a parameter through its full range. I guess you have to weigh these factors against the convenience of being able to reach for any control and smoothly take up from its stored value.

In use, the most important knobs are free of zipper noise, although some stepping is audible on controls such as oscillator level and filter envelope amount. Turning an encoder very gently will show the currently stored value on the LCD, as does pushing the compare button. Whilst both of these techniques are fine, it occured to me that, now that the Evolver is blessed with a real display, it would be great if the old value and the new one were shown side by side as you edit. Of course, the main benefit of the display is that you can name your patches and don't have to remember those cryptic abbreviations.

To further speed up programming, several nifty shortcuts have been implemented — for example, holding down an oscillator select button will solo its output. The same principle is applied to LFOs and modulators too, so top marks for consistency and operability.

Evolver Family

Right from the start, the Evolver range took the unusual step of offering the facility to stack multiple units to build polyphony. Any combination of table-top, poly-rack or either of the keyboard models can be connected, up to a limit of 20 voices. So, a four-voice rack unit could serve as a 'hands off' voice expansion unit for the Mono Keyboard to give you a five-voice Evolver — a tempting combination.

To find out more, check out the original Evolver review in the February 2003 issue of SOS. The four-voice version was reviewed in the December 2004 issue and the five-octave, four-voice polyphonic keyboard in the March 2006 edition.


It's worth remembering that the Evolver was feature-rich from day one. We've covered this ground in depth in previous reviews, so a brief summary will suffice here.

Each Evolver voice consists of four oscillators, two analogue and two digital. The analogue oscillators feature the expected triangle, sawtooth and variable pulse waves, plus oscillator sync. The digital oscillators have their own specialities in the shape of ring modulation and FM, and are stacked with a total of 128 waveforms, 32 of which may be user-imported waves. There is an excellent, free program linked from the DSI web site that will import small waves for you and transmit them to the Evolver; the PC version will even downsample large WAVs, but remember they need to be single-cycle waveforms. A length of 128 samples works best. This utility is highly recommended if you own any Evolver model.

The digital oscillators offer a wide range of sounds from bright and bell-like to harsh, deep and buzzy. Their quality is unashamedly lo-fi, imparting a delicious, aliased flavour only partially sweetened by the twin analogue filters. If you've grown used to the lush, reverb-soaked tones of a modern workstation, the Evolver's rather brash, in-your-face character might take some getting used to. If you are a bit more old-school, or a fan of the PPG or Prophet VS sound, you'll be right at home.

Past Evolvers' factory sound sets were dominated by the strange and the dirty. This time there's been a definite — and welcome — lurch towards normality. Many of the factory patches are actually playable (!) and there's a decent selection of analogue solo and bass patches, reminding us that it can do fat and warm too.

The four banks of 128 patches are arranged according to type, with the first two banks intended for keyboard performance, the third full of sequences and the final bank a mixed bag of weird drones, external signal processing and so on. All can be overwritten, and that's just what I suggest you do, as having a generous array of controls opens up the Evolver's synthesis way beyond the dreams of the original matrix.

Originally, all the controls sent and responded to System Exclusive messages only. Now there are over 40 MIDI Controllers that the Evolver responds to, which is ideal when you want to drive it from an external sequencer. Usefully, you can now address the cutoff frequency and resonance of both (left and right) analogue filters as discrete modulation destinations, which is ideal, whether you're processing external signals or just creating dynamic stereo patches. Where applicable, the OS enhancements apply to all Evolver models.

Sequencer & Arpeggiator

Tucked away, unmentioned anywhere on the panel, lurks an arpeggiator. The manual is almost apologetic about slipping this one in, yet it really needn't be. Now that a keyboard has been added to the Evolver, I suspect an arpeggiator would be the next item on most personal wish-lists.

Dave Smith MEKThe arpeggiator is activated by holding down the Reset key in conjunction with any of the four Sequence Select keys. This prodedure selects any of the four available arpeggio directions — up, down, up/down and 'play order', the only significant omission being 'random'. To latch the arpeggiator, hit the Write key and play some notes. To wipe these latched notes, hit Reset. This becomes simple enough once you've done it a couple of times. Finally, to stop the arpeggiator, the Sequencer Start key is used, which incidentally renders the sequencer and arpeggiator mutually exclusive.

The four-row step sequencer has been discussed previously, so all I want to say here is that the updates since our first review have been everything I personally hoped for. The primary enhancement is the ability to step the sequencer from the keyboard, thus offering a marvellous source of subtle or freaky tonal changes. Think of each sequencer row as a series of up to 16 stored modulation amounts, and remember that each row can have its own length (up to the 16-step maximum). If you experiment with the vast number of possible destinations for each sequence, you'll soon see how much fun this can be. Perhaps you might want to introduce occasional flurries of vibrato, or to vary the delay time unexpectedly on only a few notes. Perhaps you wish that after every dozen notes you play, the next two notes will be automatically transposed by an octave. That sort of thing...

The sequencer can also now output a series of notes or Continuous Controllers for each of its rows, although only on a single MIDI channel.


In a sense, the Evolver has come full circle, returning to its roots as a monophonic instrument. It has been fascinating to watch the progression through inexpensive yet powerful synthesizer to polyphonic but less accessible rack, to a large, gorgeous but probably unattainable keyboard before returning to this: in my opinion, the coolest incarnation yet. Not evolutionary in the Darwinian sense, this is intelligent design in action, steadily and carefully planned to bring you an instrument whose detailed synthesis is paired with a generously endowed interface. The MEK feels complete. Other than the usual moans about external power supplies, there are no major compromises.

The use of encoders might not fit your personal taste, especially if you like to 'see' a patch by the physical position of knobs. I coped OK with them and found the user interface liberating, although I did occasionally, perhaps due to my troglodyte nature, find myself seeing stars after lengthy, close-up exposure to those bright blue LEDs.

The MEK hasn't been around long, and during the course of the review, I encountered a few bugs. I compiled a list and emailed it to Dave Smith who replied to say he'd take a look. Within a few days, an email arrived with a new OS attached — all bugs fixed. I mention this because it's how it should happen, but rarely does.

I unashamedly admit to loving the Evolver sound, whether derived from those 'trashy' digital oscillators processed through smooth analogue filters, or from the analogue oscillators mangled via tuned delay, grunge and distortion. It's almost indecently full of wild and wacky sonic textures. With modulation sourced from multiple sequencers, LFOs and envelopes, you really shouldn't struggle to find inspiration if programming synthesizers is your thing. The stand-alone solo synth isn't dead yet! 

Published December 2006