The Dave Smith Instruments Evolver is an inexpensive monophonic synthesizer module and signal processor that combines digital and analog technology. EM explores its capabilities for producing new and unusual sounds.

It's practically impossible to review the Evolver, a monophonic analog-and-digital hybrid synthesizer from Dave Smith Instruments, without first focusing on Dave Smith himself. His contributions to the field of electronic musical instruments — including the Sequential Prophet-5, wave sequencing, and a simple idea that grew to become the MIDI specification — have already given him a degree of immortality. Consequently, when he built and began selling a new instrument of his own design and under his own name, EM had to take notice.

Weary of software theft and willing to buck the trend toward software-based instruments — a trend that Smith helped initiate with Seer Systems Reality — he has produced what he calls “the ultimate dongle”: a hardware-based instrument. The Evolver combines digital and analog oscillators, digital and analog filters, an analog-style sequencer, external-audio-processing capabilities, and a matrix-style user interface in a tabletop synthesizer and effects box that's capable of producing sounds like no other.


The Evolver is housed in an unassuming black steel box with a slightly sloped top covered by a blue vinyl control panel. At the top of the panel is a row of eight infinite-rotation rotary encoders with a button labeled Main to their left. With the button in one position, the eight knobs select Programs and Banks, set the master transposition, change Volume, and control the sequencer clock. In the other position, they control other global parameters such as Fine Tune, MIDI Channel, data filtering, and so on.

Below the knobs is a printed matrix that lists 128 parameters (see Fig. 1). Half the parameters are selected by pressing one of eight buttons to the left of the matrix and then turning a knob. You select the other half by first pressing and holding the Shift button, which locks when you double-click it. Two additional buttons are devoted to the sequencer, and the Reset button turns all notes off and resets all MIDI controllers. All knobs and all but two buttons each have an associated LED that lights to indicate whether it's active.

The Evolver's user interface harnesses the time-honored tradition of parameter names printed in rows below reassignable knobs, serving the same noble purpose they have in earlier instruments: economy. Indeed, the Evolver's economy extends to size as well as cost. If any other type of user interface had been used, the front panel would have needed to be much larger. As I learned my way around the Evolver, I discovered other cost-cutting measures. For example, although the knobs feel reasonably solid, the buttons are tiny and flimsy, more suited to a clock radio than a piece of studio equipment.

For heavy-duty programming, then, it would make sense to rely on a software-based graphic editor such as Emagic SoundDiver (see Fig. 2). Fortunately, you can download a SoundDiver adaptation from the manufacturer's Web site (www.davesmithinstruments.com). If you happen to own a Peavey PC 1600x control surface, you can download presets for controlling the Evolver. You'll also find scripts for naming Evolver Programs in Steinberg Cubase. In addition, MOTU Unisyn 2.0 offers an Evolver editor, and you can download Matthew Davidson's editor application for Mac OS 9 (http://apocalypse.org/~matthew/resources/evolver/).

The value of the selected parameter is shown in a large, three-digit LED not unlike those found on Sequential synthesizers of yesteryear. The disadvantage of such a display, of course, is that it can't show real words, only numbers and cryptic abbreviations. It also means that Programs can't have names on the control panel — only numbers.

Because there's no dedicated Volume knob, you can't instantly change the Evolver's output level unless the Main button is in the correct position; in some circumstances, that could be a problem. I'd also appreciate being able to select Programs directly from the front panel without having to turn a knob in order to step through them.

The Evolver's rear panel is best described as “no-frills”(see Fig. 3). It has two ¼-inch audio inputs, two ¼-inch audio outputs, three MIDI ports, and a power jack. I was disappointed by the lack of an output for stereo headphones, and neither output jack serves that purpose. (You could always use an adapter, but it wouldn't be stereo.) Also conspicuous in its absence is a power switch. I already own too many devices without power switches. Was it really cost prohibitive to add a single switch or a Volume knob with an Off position? I'd have gladly paid a few dollars more for their inclusion. The Evolver draws its power from a 13V wall wart that's accompanied by enough adapters to operate nearly anywhere in the world.

The 64-page manual, which is provided in paper form, is well organized and informative. Because it has no index, though, I was pleased to find a searchable PDF version on the manufacturer's Web site. The manual begins with a very brief tutorial section and follows with frequently asked questions, overviews of the user interface and sequencer, and detailed explanations of every programming parameter. Near the end are lists of modulation destinations and sources, as well as information on the Evolver's MIDI implementation.


The Evolver's synthesis architecture is unique, but it should be familiar enough for any experienced synthesist to grasp quickly. First and foremost is the presence of two traditional analog oscillators and two digital wavetable oscillators. Each oscillator pair is assigned to separate stereo signal paths — individual oscillators hardwired either left or right — and those paths carry the signals through all subsequent processing stages, extending all the way to the audio outputs. The Evolver is monophonic, yes, but it's a true stereo instrument. In combination with two such different oscillator designs, its stereo nature gives the sound a wonderful depth and dimension that most mono synths are sorely lacking.

The Evolver's two analog oscillators are pretty standard, offering a choice of sawtooth, pulse, and triangle waveforms as well as a combination of sawtooth and triangle. The pulse wave provides full-range pulse-width modulation — just as you would expect in any serious subtractive synthesizer — and you can narrow its width down to nothing. One analog oscillator can be hard-synced to the other for thick, biting timbres when one is modulated by an envelope generator.

Smith modeled the Evolver's two digital oscillators after those of the Sequential Prophet-VS, a classic instrument that he designed in 1986. In fact, they contain the same 95 sweepable 12-bit wavetables as the VS oscillators (minus noise, which is supplied by the noise generator). Love it or hate it, they exhibit the same audible aliasing in the upper frequencies. You can also load 32 of your own wavetables into the digital oscillators (as you could on the VS), but you'll have to wait until software is available for that purpose. The digital oscillators offer frequency (FM) and ring modulation, and either oscillator can modulate the other, even simultaneously. The resulting timbres can quickly get out of hand.

Each oscillator provides a separate Glide parameter, so you can independently assign portamento to any of the four oscillators. When you specify different Glide rates for each, the resulting animated sound can make you quickly forget that you're playing a monophonic synthesizer.

The signal path has two dedicated stereo filters — an analog, lowpass, voltage-controlled filter (VCF) and a digital highpass filter. You can toggle the VCF's cutoff slope from 2-pole to 4-pole, effectively altering its character from fat to fatter, and turn up the resonance to drive it into self-oscillation in 4-pole mode. A parameter called Split emphasizes the filter's stereo characteristics by allowing you to raise the left side's cutoff frequency while lowering the right side's. I'd rather have independent control of two lowpass filter frequencies, but short of that, Split's implementation is an imaginative solution. Normally, the stereo 4-pole highpass filter is placed after the lowpass filter and voltage-controlled amplifier (VCA), but when you're processing external signals, you can place it before the VCF for greater flexibility.

The Evolver provides three ADSR envelope generators (EGs). One is hardwired to control the filters, another to control amplitude, and the third may be routed to any modulation destination. However, you can assign any of the three EGs to any modulation destination.

Four identical LFOs are also assignable to any destination you please. Each LFO generates five waveforms and syncs to the sequencer or MIDI, if desired. At its lowest frequency, the LFO cycles only twice a minute.

One of the Evolver's programming features is tunable Feedback. Each channel has a tuned delay line; most of the time, it simply adds an interesting distortion by emphasizing the Feedback frequency. At high Feedback levels, the Grunge parameter makes the sound considerably more aggressive. You can also play melodically by modulating the Feedback frequency with the sequencer. When you route the signal back to the filter inputs, the result is essentially Karplus-Strong plucked-string synthesis.

To aid in your quest for radical timbres, the Evolver offers additional methods for distorting audio. You can place the stereo digital distortion processor either before the analog filter, where it affects only the external audio inputs, or after the VCA (but before the delay processor). An Output Hack parameter imparts an especially noisy form of distortion. You can also mangle an external signal with Input Hack and then soften its effect with analog filtering.

Like any sophisticated synthesizer, the Evolver relies heavily on its modulation capabilities. You can route 24 sources to any of 55 destinations, but the way that control signals are routed, each source can have no more than one destination. However, that limitation doesn't appear to be a serious problem because it's not entirely true. You also have four user-definable modulation routings in addition to four predefined external modulation sources: mod wheel, Aftertouch, breath control, and MIDI foot controller.


The ability to process external audio is part of the Evolver's raison d'être. You've never had so many ways to distort, twist, and mangle any sound. To that end, its stereo inputs can handle a wide range of signals, from line levels to high-impedance signals from guitars and keyboards. As an aid to setting the input gain, the front-panel LEDs serve as peak-level meters in combination with the main display, which shows the input level in 3 dB increments. Thanks to its many forms of distortion, the Evolver excels as a distortion processor.

A digital envelope follower responds to signals present at the left input; you can assign it as a source for any modulation destination. Likewise, the Peak Hold parameter can use the changing level of the left input as a modulation source. Typically, these sources are especially useful for modulating filter and envelope parameters, but you can achieve some unorthodox effects by applying them to modulate oscillator frequency or delay time, for example.

The Evolver's only traditional time-modulation effects processing is a 3-tap stereo delay line. Regrettably, the delay is monaural, which precludes programming cool stereo ping-pong effects. Nonetheless, the Evolver's factory Programs make extensive use of the delay, squeezing every ounce of functionality from its three taps. There's no reverb, but you'd never know it to hear some of the Programs. I wish that a built-in reverb processor had been included; I'm sure, however, that that would have driven the cost up considerably. You can use the Evolver solely as a freestanding effects processor, but it probably won't take the place of a more general-purpose multi-effects box.


Nothing beats an analog-style sequencer when it comes to programming sounds that evolve. Accordingly, the Evolver's sequencer is an essential part of its design. Although the Evolver has only 8 knobs, they function as if they were controlling a sequencer with four rows of 16 knobs. In essence, the sequencer stores four sequences that run in parallel. Each has a maximum length of 16 steps, and you can set the length of each independently; for example, two 16-step sequences can play alongside an 8-step sequence and a 5-step sequence. You can't, however, chain one sequence after another. In addition, the sequencer does not transmit MIDI data.

Each sequence is a modulation source that you can assign to control oscillator pitch, filter frequency, or any other modulation destination. Most of the time, at least one destination will be pitch. Of particular interest to microtonal musicians is that pitch is adjustable in quarter-tone increments. By assigning each row to modulate a different oscillator's pitch, the sequencer can even play four-note chords. Try doing that with any other monophonic synthesizer! One of the most important sequencer applications is modifying the digital oscillators' wavetable for wave sequencing.

Programming the sequencer is easy enough. By pressing the Sequencer button in combination with the Main button's two positions, you can turn the knobs to specify the value of each sequencer step, either as it's stopped or running. It also responds to MIDI notes for entering pitch, much like step-time entry in a computer-based sequencer.

As with the LFOs, you can slave the sequencer clock to MIDI. Except for applying the clock's Swing parameter, all steps are of equal duration, but you can simulate rhythmic variety by defining selected steps as rests. I used to own an analog sequencer that let me assign one row of knobs to determine the duration of each step, and I'd love to be able to do that on the Evolver.


The Evolver's emphasis is on making sounds that change over time — evolving, if you will. The sequencer's ability to modulate any mod destination helps a lot in that department; a sound can change quickly or slowly, subtly or radically, with as many as 16 distinct phases. Add to that four LFOs, four fixed modulation routings, and four user-assignable modulation routings, and you're well on your way to breathing life into your music.

You might be confused if you first connect a MIDI keyboard before you begin to explore the Evolver; that's because the first Bank of 128 Programs contains sequence-driven sounds, and the first 69 don't respond to MIDI notes. To hear those, all you need to do is press the Start button. By combining analog and digital timbres, the first Bank does a fine job of showing off what the Evolver can do. You're sure to be amazed at the variety of tones that spill from your speakers. Most of those Programs, however, do more to show off the Evolver's capabilities than to serve any useful musical function. I hope that many factory Programs will be replaced as talented programmers get their hands on the Evolver.

The second Bank's Programs are keyboard oriented, and most of them are programmed to respond to various real-time control parameters such as Aftertouch and the mod wheel. Bank 3 is a mixed bag containing drones, sequence tones, and keyboard timbres. Some of the drones are perfect if you're scoring a sci-fi film and need to impart an alien atmosphere. In addition, 20 Programs in Bank 3 are for processing external audio inputs, and half of them are specifically intended for electric guitar. The guitar-oriented Programs are especially fine, probably owing to Smith's previous work on the Roger Linn Design AdrenaLinn, but I wish there were more of them.


You say you want an evolution? Dave Smith has done his best to supply you with the next step in audio synthesis at a reasonable price, and he's succeeded admirably well. Costing not much more than some soft synths, the Evolver packs a lot of sound-design and sound-manipulating power into a desktop unit that's smaller than most software boxes. And like any good synthesizer, the Evolver is a boxful of fun that will keep you tweaking and making music for hours at a time.

Other than a few rather expensive modular synthesizers, I haven't seen another instrument that combines analog and digital oscillators since Roland introduced L/A synthesis in 1987. The Evolver is one of those few electronic instruments that sound totally original. I can guarantee that if you buy one and learn to program it, you'll be making sounds that you'd never make without one.

EMassociate editorGeary Yeltonlives in Charlotte, North Carolina. He has been playing, programming, and writing about synthesizers for 30 years.

Evolver Specifications

Sound Engineanalog and digital subtractive synthesisPolyphonymonophonicPrograms(384) rewritableOscillators(2) analog with 4 waveforms, hard sync; (2) digital with 128 wavetables, FM and ring modulation; (1) noise generatorFilters(2) voltage-controlled, analog resonant lowpass, switchable 12 or 24 dB per octave; (2) digital high-pass, 24 dB per octaveAmplifiers(2) VCAsEnvelope Generators(3) ADSRLFOs(4) multiwaveform with MIDI syncEffects3-tap delay with MIDI sync (1 sec. maximum); stereo digital distortionSequencer4-parameter × 16-step analog-style with MIDI syncA/D/A Conversion48 kHz, 24-bitAnalog Audio I/O(2) unbalanced ¼" TS inputs; (2) unbalanced ¼" TS outputsMIDI I/OIn, Out, ThruFront-Panel Controls(8) infinite-rotation rotary encoders; (13) buttonsDisplay3-digit LEDPower Supply13V wall wart, 100-240V ACDimensions10.75" (W) × 1.50" (H) × 6.00" (D)Weight3 lb.


Dave Smith Instruments
synthesizer module


PROS: Innovative architecture. Stereo I/O. Real analog filters. External audio processing. Cool distortion effects. Flexible hands-on sequencer. Lots of unique timbres.

CONS: No headphone output, power switch, or dedicated Volume knob. Three-digit display. Flimsy buttons. No reverb.

Dave Smith Instruments
tel. (707) 963-7006
e-mail mail@davesmithinstruments.com
Web www.davesmithinstruments.com