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What Is It?
Vokator is a highly flexible synthesizer/effects processor based on phase vocoder technology. It can function either as a stand-alone instrument or as a plug-in under Mac OS 9 or X, and Windows 98/ME/2000/XP. It offers a flexible voice architecture with free selection between external inputs or internal sources for both of the two signal paths. The internal signal sources include straight playback of a sound file or either of two synthesis methods from the built-in polyphonic synthesizer. There is also a complement of signal processing modules for the two inputs and the output, with dynamics, chorus, and a selection of effects algorithms that take full advantage of the phase vocoder architecture. This is no perfunctory "me too" software vocoder with a few bells and whistles - the designers have immersed themselves for some time in the technology and lore of vocoding and have emerged from their chrysalis with a gorgeous butterfly of an instrument.
Before you proceed you may want to brush up your knowledge on the history and basics of vocoding technology. You can do so by reading Richard's Vocoding 101 article here.
Installation and Documentation
Installation is as straightforward as for other Native Instruments products. A single Mac/Windows CD provides installers for the various OS versions. The process is a simple click-through sequence, plus the requisite entry of the serial number (Challenge/response authorization to be implemented in future updates). The last stage of installation is an optional on-line registration at the NI Web site - registration is highly recommended, as it give access to on-line support, future updates, and a user forum. Performing the installation in OS X left me with a stand-alone version of Vokator that runs under either OS 9 or X, as well as VST plug-in in both Carbon and Classic form. There is a VST instrument version and an effects version for each.
The manual is NI's usual polyglot paperback with 90+ pages per language. It's clear and well organized, with a decent index. Especially helpful is the section addressing specifics of working within various host applications such as Cubase SX, Nuendo, and Logic.
Voice/Processing Architecture
Basic vocoder design is built around two channels with two two inputs, for the carrier and program signals. Both of these can be fed by external signals, or in many analog designs the carrier signal is supplied by a built-in oscillator or polyphonic synthesizer. Some analog vocoders also allowed some manipulation of the frequency spectrum, particularly for emphasis of certain ranges. The Synthovox even allowed cross-patching of analysis and synthesis filter bands for special effects.
Vokator builds on these familiar features with a stack of its own. It offers three internal signal generator options: a file player that can be used in lieu of external input A and a synthesizer that can play either oscillators or a sample in lieu of input B. Management of the two channels is also flexible. Rather than being bound by a strict assignment of "carrier" and "program," Vokator simply designates the two channels as "A" and "B" and allows them to operate in any of five modes: A*B, B*A, Mix, A+B, and Group. "A*B" and "B*A" are just mirror images of each other, allowing either input to be the carrier or the program. This is a simple way to take advantage of the different playback systems built into the two channels. "Mix Mode" combines the signals from A*B and B*A with the direct signals from the sound generating modules, with level and pan control of each. This sonic richness comes at the price of a greater CPU load (my G4/800 PowerBook can register up to 60% CPU load). "A+B Mode" bypasses the vocoder functions entirely; it allows mixing of the two inputs, the file player, and the synthesizer as well as use of the output compressor and EQ. Finally "Group Mode" allows simulation of classic channel vocoder by combining frequency bands into anywhere from four to 32 groups. These may be "cross-patched" so that a given frequency band from the carrier signal can be used to control the amplitude function of any other band of the carrier. Group mode also provides some tweaking of its bands, with Smooth, Overlap, +/-, Bandwidth, and Frequency Offset allowing shaping of the filter characteristics (e.g. temporal "smear," frequency range, etc.).
There are two built-in signal sources. File Player (AKA "Tape") is available as an alternative to Live input on Input A. As its name suggests it is a simple monophonic sound file player that can be set to loop continuously or can be triggered by MIDI notes. It always plays back at its default pitch, but its start and end times can be set anywhere within its overall length. Input B offers a choice between Osc Synth and Wave Synth. The former has two variable waveform oscillators, a multimode filter, and an amplitude envelope. The oscillators are efficient and flexible, with continuous control over waveshape and harmonic content. Oscillator 2 can be frequency modulated by Oscillator 1. Wave Synth is a straightforward sample player; it replaces Osc Synth's two oscillators with a single sample playback window and keeps the filter and envelope. It doesn't have the fancy features of most stand-alone samplers, but it does a good job within Vokator (if you need more, you can plug your fancy sampler into a live input). It does offer a variety of loop modes (forward, backward, forward<->backward, loop in release, etc.). One especially happening feature of both Osc and Wave Synth is the Morph feature. Five separate presets can be saved as a Morph set and you can interpolate between them using the Modulation Wheel (CC 01). Note that the function is "hard-coded" to the Mod wheel (and this makes CC 01 unavailable for other control functions). I personally don't find that to be a problem, since Morph is so powerful that I'm sure most users would rely on it extensively.
There are also several DSP effects that may be applied to the input and output stages. The output effects are straightforward spectral shaping (filtering) and a compressor. In contrast, the Input Modulation Effects are varied and exotic, and they are at work deep within the phase vocoder function of Vokator. Some of these algorithms produce effects that superficially resemble more prosaic processes such as phasing and filtering, but they are achieved with great precision and often novel results. "Deterioration" uses pseudo-random operations to produce "holes" in the spectrum. These density and duration of these holes is adjustable, producing effects that can resemble a cross between amplitude modulation and arpeggiation. "Time Sponge" dynamically alters the sense of time of the input signal. It can produce a range of stutter, freeze, and tremolo effects that are especially effective when dynamically varied. "Mini-Pulses" is a very severe gating effect with adjustable feedback that can produce sharp "chop" effects or more full-bodied pulsations.
Rather than the dozen or two individual frequency bands of an analog vocoder, a digital "phase vocoder" can have hundreds! Vokator provides up to 1024 bands. Not only does the much greater number of bands support a higher-resolution, more natural sound quality but by being in the digital domain it permits a wide range of resynthesis effects such as pitch shifting, time scaling, and formant manipulation...not to mention unlimited channels. This level of number crunching used to limit phase vocoding to non-realtime functions, but Vokator happily takes advantage of modern CPUs and runs in real time with moderate latency.
Programming Interface
Vokator has a programming interface consistent with other Native Instruments products, and especially similar to Kontakt in the way it gives the user the option to hide or display various functional components at a mouse-click. Most multi-value parameters are set with graphic rotary knobs or sliders; others are toggled between binary states with buttons or chosen from popup menus. Both the File Player and the Wave Synth have small waveform displays. File Player allows you to select a playback region from the file by clicking (Start point) or Control-clicking (End point) with the mouse. Curiously, the Wave Synth does not observe this convention. It allows setting of the Sample Start point with a graphic slider and the Loop Start and Loop Length points with rotary pots. The graphic knobs and sliders work fine, though I'm a particular fan of direct numeric entry and would have liked that option as well.
Both Osc Synth and Wave Synth have graphic displays for such parameters as oscillator waveforms, filters, and envelopes. Control over the shapes of these functions is offered in a compact interface, were individual sets of graphic sliders surround the function windows on their four sides. The oscillators in particular have a clever design, with waveforms continuously variable from sine to triangle to square to white noise, with a continuous symmetry control that similarly allows (e.g.) variation from triangle to sawtooth or square to narrow pulse wave.
One of the nice touches in the interface is the ready accessibility of libraries. You can maintain collections of presets, samples, and so on wherever you like on your computer system and specify search paths for each category. The libraries will then be available to a variety of popup menus interspersed throughout the user interface. Very handy!
Modulation and Control
Vokator has four types of built-in modulation sources: two Step Sequencers, four LFOs, two Voiced/Unvoiced Detectors, and two Envelope Followers. These can be assigned to virtually any parameter. Modulation assignment is quick and easy - simply click the "Assign" button associated with a particular modulation source and then click and drag over the parameter range to be set. Several parameters can be set at the same time. To de-assign the modulator or to assign to external MIDI sources, just Control-click (Right-click in Windows) on the parameter control to pop up a menu showing the various options. A "MIDI Learn" function makes external control assignment just as simple. We've already mentioned the Morph function, which provides single-controller performance of multiple simultaneous parameters. The two systems taken together are actually quite powerful: you can choose to make large gestures that control several parameters as a group, or you can tweak elements of the sound individually with separate controllers.
The Step Sequencers can have from 2 to 32 steps and can run freely or in sync with a host application's tempo. They can control any of Vokator's modulatable parameters. The four identical LFOs have a frequency range of 0.1Hz to 12Hz (not fast enough!) and a selection of sine, square, sawtooth up, sawtooth down, triangle, and random waveforms. The can run freely or in sync. The envelope followers and voiced/unvoiced detectors are hard-assigned to the two inputs. The followers offer Depth and Sensitivity adjustments and the detectors offer Threshold and Smoothness.
One more built-in control goody is the Integrated Keyboard Module that is part of the Osc and Wave Synth. This can function as a substitute for an external MIDI keyboard, but it has the added feature of the Chord Memory module. This allows saving of 12 different chord presets that can be recalled manually, under MIDI control, or via the module's own sequencer.
How Does It Sound?
I'm confident in saying that Vokator is the best-sounding real-time vocoder I've ever heard. It's also the most versatile, which is another way of saying that you can get it to "sound" a whole bunch of different ways. These ways can range from gorgeously ethereal to nastily industrial to downright lounge-cheesy, and because of its comprehensive architecture it can be treated as an effects processor and as a performance instrument in its own right. The base line for all of this is well-designed DSP code that provides high resolution and glitchless real-time control. It also helps that Native Instruments have packaged a varied and interesting set of samples and presets with it. A quick run through the demo presets will give you a decent overview. He are just a few:
"A chord talk" plays a looping vocal sample on Input A and uses Osc Synth on Input B with the B*A vocoder mode and 512 bands. The synthesizer is controlled by a Chord Memory sequence playing a progression of minor seventh chords with a suave organ timbre. The effect is a familiar "talking organ" sound but with much higher resolution than your father's Korg. In contrast, "Classic vocoder" constrains the vocoder to 32 bands (in Group mode) and uses a plain sawtooth. The effect is as its name suggests, rather flat and robotic (but without that nasty "electro-kazoo" quality). "Spec techno 1" is a whole 'nother animal, using A*B mode with a drum loop on Input A and a heavily LFO-modulated Osc Synth on Input B to produce an industrial dance beat. "Dirty ole piano" is still another approach, using A+B with Live input on Input A and a piano sample, with arpeggiator, on Input B. The main event in this example is the use of Morph, which not only allows dynamic interpolation among five filter settings but also slides the sample loop's start and end points back and forth as you wiggle the mod wheel. Stunning!
Technical Problems and Support
Everything ran smoothly under Mac OS 9 in both stand-alone and VST plug-in modes, but when I first tried Vokator in OS X on my G4/500 I experienced severe glitching. This sounded like the signal was being modulated by a pulse wave, and after trying a few things without success I decided to report the problem through NI's on-line tech support. A response was waiting for me the next morning, informing me that it's a known problem with a fix on the way. To quote: "This is caused [by] the envelope generator that is re-triggered for each step of the 'chord memory' sequencer."
After noticing a few other weirdness, and acknowledging that my desktop Mac hasn't been above reproach of late I decided to try Vokator under OS X on my PowerBook G4/800. I did NOT experience any glitching at all, so I'm inclined to say not to worry.
On the basis of the quick response and past experience with other product questions I give high marks to Native Instruments' tech support. I've had timely and helpful support through both telephone and Web site. I've even got to know members of their support staff face to face, and I can attest to their expertise (and to their enthusiasm for NI products).
Summary
Vokator is the best real-time software vocoder yet to appear, and it is at home on both PC and Mac. It has a well-designed and flexible built-in synthesizer and a range of effects algorithms that are beyond the usual. For those seeking a retro sound, it does a credible simulation of classic analog channel vocoders. For those looking ahead it offers advanced spectral-shaping features that defy simple classification. It inhabits an interesting realm between effects processor and playable instrument, and because of the nature of vocoding it can assimilate the sonic characteristics and behaviors of whatever sounds one feeds into it. This makes it adaptable to practically any genre of music.
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