Evolver Review by Richard Zvonar

WHAT IT IS

Evolver is a monophonic hybrid synthesizer with abuilt-in step sequencer. This may sound simple and straightforward, byI assure you... it ain't necessarily so. Most of us understand "monophonic"(as opposed to "polyphonic") to mean that an instrument canplay a single tone at a time, yet I found that many of Evolver's presetvoices are playing in harmony or produce complex layered sounds. Thisis courtesy of a voice architecture that combines two analog and two digitaloscillators with multiple resonant filters, and which allows independentcontroller routing for each. Evolver also accepts input signals as bothaudio and control elements. For those who need added polyphony, multipleunits can be linked.

THE SOURCE

One of my favorite things about Evolver has lessto do with the instrument itself, than with where it comes from. Thatis, when the label on the instruments reads "Dave Smith Instruments"it means literally that - Dave Smith is personally designing and buildingEvolver. Not only that, the company is in St. Helena, a charming communityin the heart of California's Napa Valley wine country. Many of you knowthat Dave Smith was the founder of Sequential Circuits, the principaldesigner of the MIDI specification, and a pioneer in the development ofsoftware synthesizers for the PC as a partner in Seer Systems. There issomething delightfully utopian about Dave comfortably ensconced in St.Helena, creating electronic instruments to his own fancy and producingjust enough of them to have a healthy and manageable one-man business.

Well to be truthful, I expect Dave does have someamount of help - he probably doesn't drill all the holes or stuff allthe boards himself. And his designs don't come out of a vacuum. In additionto his many years working with the Sequential and Seer teams he also hasa longtime working relationship with the Roger Linn (at one time theywere even doing business under the moniker of "Rave and Dodger").According to Dave, the inspiration for Evolver came while he was helpingRoger with his Adrenalinn project (the physical resemblance between thetwo units is clear). After years of working entirely in software, it wasrefreshing to work in hardware again.

HARDWARE

The physical unit is solidly built, with a steelchassis just 10.75 inches across and 6 inches deep. It is designed asa tabletop unit, with sloping top, and it fits comfortably next to a computerkeyboard or MIDI controller. Evolver is a two-channel stereo unit witha pair of 1/4-inch output jacks as well as a pair of inputs (allowingresponse to, and processing of, external signals). It has MIDI in, out,and thru connections and a jack for the external 13-15 VDC wall wart powersupply (the latter comes with an international adapter pack plus a ferritecollar for high frequency shielding).

The user interface, reminiscent of the SequentialCircuits Prophet 2000/2002, is a parameter matrix with a single row of8 continuous-turn rotary switches at the top that control the parametersof the currently-selected row in the matrix. There are 10 such rows, eachchosen by pressing a corresponding button, and the number of programmableparameters is multiplied by the use of a Shift button and a Sequencerbutton. This method grants quick access to a great many parameters withoutthe menu/submenu system found in many other digital instruments. And indeedthere are many parameters! In addition to a double-row of 20 Main, orsystem-level parameters there are 128 program parameters that addressaudio parameters such as oscillator and filter settings as well as modulationand time functions. When the interface is switched to Sequencer mode,the 8 x 8 matrix is used to program (or perform) the 16 x 4 sequencer.In this mode the rows are grouped in pairs (steps 1-8 and 9-16) for thefour sequencer tracks. Visual feedback for all this programming is providedby a large number (20) of LEDs that indicate the current parameter orsequencer step, in combination with a three-character alphanumeric display.It's a lot of information to squeeze into a small display, but once you'refamiliar with the shorthand it's not bad.

VOICE ARCHITECTURE

In order to get a better visual overview of its voicearchitecture, you might like to check out a PDF of the Evolverblock diagram. The first thing you should notice is that despite beinga "monophonic" instrument in the sense of playing one note ata time, Evolver is fully "stereo" in the audio sense, with twoinputs and outputs and a pair of identical signal generation and processingchains."

Evolver is a hybrid synthesizer and effects processor.The two analog synth sections each contain an analog waveshape oscillator,a 2/4 pole resonant lowpass filter, and a VCA. The digital component provideswhite noise, two wavetable oscillators, pan, highpass filters, delay lineswith tuned feedback, distortion, more delays with crosscoupled feedback,and "hack" (a particularly nasty distortion on the outputs).In addition, the analog input section provides an envelope follower, peak/holddetector, hack, highpass, and distortion (on Input 1) and hack, highpass,and distortion (on Input 2).

The analog oscillators offera selection of waveforms: sawtooth, triangle, sawtooth/trianglemix, and a pulse wave with a duty cycle that can be set over a range of0 to 99 (where 50 gives a square wave). The digital oscillators offer95 waveshapes that correspond to the factory waveshapes in the Prophet-VS,and 33 waveshapes that are user programmable (this requires third partyPC software, downloadable from Dave's site).

CONTROL AND MODULATION

Each analog lowpass filter has its own dedicated ADSRenvelope generator, as do the analog VCAs. By default, the filters tracktogether, but they may be decoupled to some extent. A third ADSR can beused as an arbitrary modulation source, and there are four identical LFOsthat may also be assigned to control any of 56 parameters. The LFOs maybe run asynchronously at rates from one cycle in 30 seconds up into theaudio range at 261 Hz (middle C) maximum. LFO rate settings above thisare used for synchronous operation, dividing or multiplying the sequencespeed to achieve relationships from one LFO cycle per 32 steps to sixteenLFO cycles per step.

In all there are 24 modulation sources that can besent to 56 modulation destinations. Sources include the four sequencerrows, the four LFOs, the three envelope generators, peak and amplitudeoutputs from the Input 1 envelope follower, MIDI pitch bend, mod wheel(CC 01), pressure, breath controller (CC 02), foot controller (CC 04),note velocity, note number, and expression (CC 11). Noise and Oscillators3 and 4 are also available as modulation sources. The modulation destinationsinclude the obvious parameters such as oscillator frequencies and levels,filter frequency and resonance, delay times and feedback, as well as envelopeamount and attack duration and a few other useful tweaks.

Other program parameters affect the overall functionalstate of a program and aren't subject to real-time variation. Such parametersinclude Trigger/Interface Parameters that determine how Evolver responds(or not) to the sequencer and external MIDI messages, Miscellaneous TimingParameters including BPM and Clock Divide, and Miscellaneous ModulationParameters that regulate various aspects of the real time behavior.

The control architecture is so complete (and complex)that it's possible to turn off such things as MIDI note reception, andthis can result in a few lost moments in the early stage of your learningcurve. Not being one to RTFM until desperate, at first I got derailedfor a bit when I discovered that many of the factory voices were not respondingto my MIDI keyboard, though the sequencer was working just fine. I quicklyfound the MIDI Receive parameter and made sure everything was enabled,but soon I discovered that this is not the only place where MIDI inputcan be defeated. Deeper in the matrix (Row 7, Parameter 8) is Key Off/Xpose,which allows you to turn MIDI note number mapping completely off or toa transposition value in the range +/- 36 semitones. Since there is noglobal setting for this parameter I had to set all the disabled voicesindividually. Only after I had done this did I stumble upon the statement"Bank 1 has sequencer-oriented Programs in locations 1 through 69,"lurking in the Quick Start section (which of course I NEVER read - theGreeks had a word for my ruggedly independent attitude: "hubris").

SOUND

Evolver is truly a protean instrument, with a rangeof sound production and "attitude" that is wide ranging. Itcan do your "old school" analog mono synth voicings, and itturns in a credible Prophet VS emulation (due largely to the 96 digitalwaveforms from the VS). But it goes on from there with highly flexiblesignal and control routing à la modular systems and an assortmentof wave shaping elements that can generate some serious industrial noise.This instrument has real personality! When I first heard the prototypetucked away in Roger Linn's booth at NAMM 2002 I was struck by the seriousrudeness of some of the voicings, butted up against some gorgeously sweetsounds in other presets. When Dave came back with his own booth at NAMMthis year I was there at one of the several demo stations - a lot. AndI brought my friends. Repeatedly.

An interesting thing about the voice architectureis the way its hybrid analog/digital components are integrated. Signalsources include a noise generator and two pairs of analog and digitaloscillators organized into two parallel signal chains with multiple stagesof filtering, amplitude control, distortion and cross-coupled delay lines.The output section has more delay processing and more distortion. Thisarchitecture embeds the analog elements within a digital processing shell,allowing the flexibility and precision of the latter to interact withthe warmth, grit, and nuance of the former.

Three voice banks of 128 programs offer a total of384 programs. The factory set is a real mixed bag, with an evident attemptto offer new users a maximum of variety as they switch from one programto the next. Bank 1 is divided between programs (1-69) set up for usewith the sequencer while the rest (70-127) are for sequences that areset up to be transposed by MIDI notes. Bank 2 is meant for keyboard use,with no sequences, though I did find a few lurking. Bank 3 offers a setof 20 drone programs, all of which will play merrily on their own withoutthe need of sequencer or keyboard (though most of them work well underexternal or sequencer control). These are followed by another 20 externalsignal processing patches (10 mono for guitar and 10 for stereo audio).The rest are a combination of sequence and keyboard programs.

SEQUENCER

Evolver has a 16 x 4 step sequencer designed afterthe traditional "analog" fashion. A separate sequence can beprogrammed for each program or a single sequence can be "Locked"so you can try it out with various sounds. In essence this is a singlefour-track sequence, though each row of the sequencer can have its ownstep length. This might allow a sequence in which each oscillator playsa pattern of a different number of notes, for instance 3:4:5:7, so thatthe composite would repeat every 420 notes. Each step of the sequencecan be set over a range of 100 values. In the case of oscillator frequencyeach increment equals 50 cents, so quarter tone scales are possible overa four octave range. The next value setting above 100 has the specialfunction of causing the sequencer row to jump immediately to step 1, so(e.g.) by setting step 5 to "rSt" you can create a 4-step pattern.Row 1 also allows each step to be set to "Off" in order to generaterests in the pattern (the Row 1 rest pattern will also apply to the otherrows).

Although it is customary to use at least one row tocontrol pitch, the sequencer outputs should really be thought of as generalmodulation sources capable of controlling any of Evolver's parameters.For instance, you could dynamically vary LFO frequency and modulationdepth, filter cutoff frequency, or delay feedback level as the sequenceruns. A great many of the factory programs have been designed this way.For instance, the wonderfully grungy drum and bass pattern of Program13 has the sequence rows assigned to Noise Level, Resonance, OscillatorAll Frequency, and Filter Split, while the bell-like Program 14 has rowsassigned to Oscillator All Frequency, Pan, Oscillator All Pulse Width,and Ring Mod Amplitude Amount Osc 3->4

The overall tempo and "swing" of the sequenceis set in the master parameter row by BPM (30 to 250) and Clock Div (Halfnote to 64th note with half swing, full swing, and triplet timing forthe quarter, eighth, and sixteenth notes). The sequence can also be drivenby external MIDI clock (Evolver can also send MIDI clock). There are severalways that the sequencer and the envelopes can be set to interact withincoming MIDI notes and external audio inputs. In addition to functioningindependently from each other, the sequencer can be gated and transposedby MIDI note input or by an external signal. This can be done with thesequencer in free-running mode or it can be reset each time it receivesinput. Input notes can also be interpreted in a variety of ways, suchas Low note priority, High note priority with re-triggered envelopes,Last note priority, etc.

DOCUMENTATION AND TECHNICAL SUPPORT

The 53-page manual is clear and comprehensive, witha number of useful tips and suggestions interspersed. After brief QuickStart and Basic Operation FAQs sections the bulk of the document is organizedas a reference manual, listing Main Parameters and Program Parameters,Sequencer functions, and technical data on MIDI messages and the instrument'ssystem exclusive data format. The latter has already proved useful toseveral customers who have created software editing interfaces for thePC and Mac.

Since I foolishly skipped over the introductory materialand wasted some time puzzling out what had been clearly explained, I recommendthat after a new user has had an initial playtime she or he give the doca read-through. While this instrument is cleanly designed and its parametersare well organized, there are so many options that those new to modularsynthesis can get a bit lost.

Support issues are handled by Dave Smith personallyvia e-mail. He has a reputation for being friendly, helpful, and quickto respond, so I sent in a query about my little problem with Key enable.My message went out at 3:32 PM PDT. Dave's response was sent at 7:42 AMPDT the next morning. It was friendly and helpful, and the man is obviouslyan early bird.

The DSI Web site also has a technical support sectionwith a FAQ, troubleshooting tips, and a download page that at this writingcontains sys-ex files of the factory programs, the Evolver manual in PDF,Sound Diver adaptations for PC and Mac, and other useful software. Thereis even a standalone editor for the Macintosh, made with Max.

SUMMARY AND CONCLUSION

Evolver is a wonderfully designed and amazing-soundingmonophonic synthesizer that combines the sonic characteristics of analogoscillators, filters, and VCAs with the precision and flexibility of digitalsignal processing and control. Its 4-track step sequencer gives plentyof control flexibility to allow the instrument to work standalone, butit works well under MIDI control and also responds to audio input. Thereis a wealth of pre-programmed factory patches to give the newcomer hoursof immediate gratification and a hands-on education in modular synthesisand control. Those who are already well-grounded in these areas will findplenty to work with. I loved this instrument at first sight/sound andthat love grows with every tweak of a knob. I intend to keep it.

Scoreboard (0-10 rating)

• Sound 10
• Interface 8
• Construction 10
• Innovation 8
• Overall Value 9