PLUG-IN FOLDER

Virtos Noise Wizard

Formats: PC DirectX

Virtos is a new name to me, but judging by this first plug-in offering they will soon be better known. Their Noise Wizard is a collection of five DirectX plug-ins designed to remove unwanted background noises from your audio, filter out unwanted frequencies, restore missing ones and enhance stereo imaging, and runs on Windows 95, 98, ME, NT, 2000 and XP.

Noise removal is taken care of by a Declicker and a Denoiser. The former has Threshold and Max Click Size (duration) controls in the upper half of the window, and Threshold and Level controls for the optional Decrackler beneath, and removed both clicks and crackles very effectively from my range of test files. A Residual tick box lets you audition just what's being removed, which makes control setup much easier.

Denoiser offers three different ways of reducing static background noise such as hum and hiss: Noise Print, User Profile and Noise Analysis, each with a spectrum analysis window and three rotary controls. Gain Floor sets the maximum suppression level, while the Attack and Release Time fine-tune the dynamics. If you have a short section with no signal except for the background noise, you can capture a Noise Print using its Learn button, and then use this as a blueprint to remove noise from the whole file. You can determine the amount of noise reduction applied using the Level slider.

If there's no suitable section of isolated noise, User Profile lets you draw your own noise print using the mouse and a click and draggable graphic interface. This is easier than it sounds, especially with the Residual box ticked so that you just hear the extracted noise. Even easier is the Noise Analysis page, which automatically calculates a noise profile in real time. You just start playback and a graph of detected noise appears, along with a graph showing the level of noise being removed. A Freeze button lets you stop further real-time analysis if you're happy with the current results. Overall, I found the Denoiser capable of some very effective noise reduction, with minimal 'chirping' side-effects; the Noise Print option seemed most effective where it could be used.

Filter Toolbox contains a phase-linear filter whose response can be determined by clicking and dragging points on a line (see screen shot above), a Band-pass Filter section with Lower and Upper frequencies, and three notch filters with user-definable Centre frequencies. These all work well, although each control covers the entire audio range, making fine adjustments extremely tricky unless you grab the control and drag in a huge circle, and since the notches are rather wide, hums are better removed using Denoiser.

Band Extrapolation synthesizes and restores missing frequencies at both ends of the spectrum. The High Frequency section adds odd harmonics above the user-defined cutoff frequency (adjustable from 1kHz to half the sample rate), while the Low Frequency section adds odd harmonics to frequencies up to its cutoff (30Hz to 250Hz). You can then mix together the new low and high bands with the dry signal using three sliders. This plug-in provides a wide range of sounds from subtle to extreme, although sadly the harmonics aren't in phase with the direct signal, so you get a dip in the frequency response where the two cross over.

The final plug-in is Stereo Processor, which allows you to send variable amounts in and out of phase of both the left and right input signals to either output channel, adjust the phase offset between them by up to ±0.18ms, and use the Stereo Broadening control to cancel out the central image and spread the stereo effect. It's good for tweaking mixes where the stereo image has gone out of whack, or which have little stereo information, and for special effects.

Although I have a few reservations about Filter Toolbox and Band Extrapolation, they certainly produce useful results, as does Stereo Processor, but for me the highlights of the Noise Wizard suite are the denoising tools, which

work extremely well. Wavelab 4.0 has recently been released with high-quality bundled DeClicker, DeNoiser, and Spectralizer plug-ins, but for any musician without these, Virtos' Noise Wizard bundle is good value, and should help clean up your audio very nicely. Martin Walker

Noise Wizard bundle $119; plug-ins also available individually.
www.virtos-audio.com

Emagic EVOC20

Formats: Mac & PC Logic Instrument

Emagic's EVOC20 vocoder is a virtual instrument plug-in, or more correctly, a suite of three plug-ins, designed specifically for use within Logic Audio 5.0 and up, with authorisation via the XS Key. All three instruments are based around 20-band vocoder filter banks, two being true vocoders while the third utilises both filter banks to create special effects.

For those unfamiliar with the operation of vocoders, they can be thought of as devices for transferring the frequency spectrum of one sound source (the analysis input) to a second signal (synthesis input). They achieve this by continuously measuring the level of the analysis input across multiple frequency bands (in this case up to 20) and then using that information to control the levels of a second set of filters through which the synthesis signal is passed. The result is that the frequency spectrum of the analysis input is superimposed upon the synthesis input, giving rise to the famous 'talking synth' sound. However, the process isn't limited to vocals — you can experiment with any sound sources, including percussion. As with all Logic's plug-ins, any parameters can be automated.

The first of the three plug-ins is EVOC20 PS, which functions as a classic vocoder and includes a polyphonic synth for use as the synthesis input source. The synth, which provides up to 16-voice polyphony, can be played in real time via MIDI (or from a MIDI track) while the analysis input can be any audio track (selected via the Side-Chain flip menu in the plug-in window). Because the plug-in includes a synth section, it is used via an Instrument object rather than as an insert effect. Like hardware vocoders, EVOC20 PS (and TO) include a voiced/unvoiced detector to identify 'fricative' unpitched vocal sounds such as s, t and th. Noise is fed into the synthesis signal whenever these unvoiced sounds are detected in the analysis signal, resulting in better speech intelligibility.

The control section covers synthesis, side-chain analysis, formant filter, modulation, voiced/unvoiced detection and output settings. Mono and legato modes can be used with the synth section, which is based on a dual-oscillator voice structure offering multiple waveforms plus FM capability. There's also a traditional envelope shaper and resonant filter, though the vocoder often works most effectively with a harmonically rich signal, which means leaving the synth filter open or sharpening up the sound using resonance. A chorus ensemble effect can be applied to the synth sound to create a richer end result.

When the analysis signal is being processed, the attack and release time of the envelope followers can be varied, while a Freeze button holds the current analysis settings. Though using more filter bands provides better articulation, it is possible to use fewer bands (down to a minimum of five) to create special lo-fi effects. There's also a master 'pass-band' control on all three models with a range of 75Hz to 8kHz, which band-limits the signal fed into the filter section so you could, for example, trim away all the low frequencies to get a telephone effect or use it less radically to remove excessive deep bass or high end. This control doesn't appear to be modulatable in a direct way, though like all the other parameters, it can be automated.

Few hardware vocoders offer more than this, but EVOC20 PS adds the ability to shift and stretch the formants, which is accomplished by changing the synthesis filter band positions relative to the analysis filter bank. The shift may be modulated using a sine or triangle-wave LFO with its intensity controlled manually or from the keyboard mod wheel. There's also a resonance control that applies to the vocoder filter bands and a stereo width function where the bands are panned progressively according to their frequency or where alternate bands are panned hard left and right.

Offering something slightly different, EVOC20 TO replaces PS's synth section with an oscillato

This plug-in is used as an effect insert rather than as a virtual instrument. Other than that, the main operational differences between the PS and TO plug-ins relate to the synthesis section, which in TO's case can provide either a simple sawtooth wave or a two-oscillator FM sound. Pitch quantisation (with scale selection and variable correction speed) can be applied to the tracked input to create vocal effects not entirely unlike the over-Auto-Tuned effect used on Cher's 'Believe' single, though more obviously electronic-sounding. Formant shifting and stretching is similar to that available on the EVOC20 PS plug-in.

EVOC20 TO can vocode the input with itself or with its tracking oscillator. Vocoding a vocal signal with itself and then turning up the noise added during unvoiced sounds produces a curious lisping effect while using the oscillator provides more of a conventional vocoded sound, but following the pitch of the original rather than that of a separate synth part. I found the oscillator to be extremely fussy as to what kind of sound it would track happily — when fed with Susan Vega's unaccompanied 'Tom's Diner' it yodelled and bubbled like a wounded yak being lowered into boiling mud (you must have done it as a kid!). Nevertheless, on the right material, this effect can work well, and the ability to select a pitch and scale for the oscillator pitch quantisation helps avoid musically unpleasant surprises.

The third plug-in, EVOC20 FB, comprises two formant filter banks with individual level control over each frequency band. Formant Stretch and Format Shift parameters allow the band spacing and frequency offset to be modified, and it's also possible to crossfade between the two filter banks to produce some creative dynamic timbral shifts. This plug-in is used as an effect insert rather than as a virtual instrument and may be inserted following a normal virtual instrument to further modify its sound. Frequency bands can be adjusted individually or new curves can be 'drawn' on screen. Similar filter band parameters are available as to the previous plug-ins, including stereo synthesis, but in addition, overdrive and gain boost may be added. With static filter settings, the effect is not unlike that created by a graphic equaliser, but because the filter stretch and shift can be modulated, and two totally different filter band settings can be cross-faded under LFO control, the shifting timbres that can be created are actually very useful, especially for modifying bland pad parts.

EVOC20 PS produces the most familiar vocoder effects, and because of the way the synth section is designed, the quality of articulation is actually very good. Rather than being a general-purpose polysynth section, this one seems fine-tuned to produce the raspy kind of sounds needed to act as vocal excitation signals, so when they hit the filter bank, the clarity of speech is far better than you'd get using a generic pad sound. Using filter resonance in both the synth and filter bank sections can improve the vocal clarity further, while modulating the filter bank frequency produces a nice timbral shift as though the vocal source is morphing from male to female and back again. Stretching the formants can make the lower sounds even deeper and the higher ones higher, or you can go the other way and bunch the filter bands together for a more restricted effect. The stereo spread control is effective in giving the sound source width, and on the whole, I found this plug-in the simplest and most effective in the majority of applications.

EVOC20 FB is an effect rather than a vocoder and utilises both filter banks for processing, rather than one for analysing and the other for processing. It's much like having two graphic equalisers where you can draw in the EQ curves using the mouse or you can set individual faders. Using modulation to sweep between one filter bank and the other generates trippy phasing sounds and adds timbral movement that works nicely on both vocal and instrument sounds. Adding boost and distortion as well as formant shift (which is also capable of being modulated) adds to the fun. While the effects you can create this way are not exactly radical, they are musically relevant, which is what actually matters — ideal for psychedelic revival music!

As a package, EVOC20 delivers all the classic vocoder effects in a simple-to-use, good-sounding format, but then goes further to provide width and offset modulation, tracking oscillators and versatile filter banks into the bargain. As a standard vocoder, it stands comparison with the best around, and I think the designers have got the balance of flexibility versus complexity exactly right. Vocoding may be an old effect, but EVOC20 truly gives it a new lease of life. Paul White

£149 including VAT.
Sound Technology
+44 (0)1462 480000.
+44 (0)1462 480800.
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www.soundtech.co.uk
www.emagic.de