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DelayDots Spectrum Worx

Modular Spectral Effects Plug-in [Windows]
Published August 2004
By Martin Walker

DelayDots Spectrum Worx

As well as more-or-less conventional vocoding and pitch-shifting, Delaydots' new VST plug-in offers effects so bizarre they almost defy description.

Back in SOS June 2002 I reviewed a suite of three Spektral PC plug-ins from Delaydots, so named because they all operated in the frequency domain. Although each one was simple in concept, I was so impressed by their ability to alter sounds in such radical and often unusual ways that I ended up creating a bank of presets for each one, which were subsequently bundled free with the package. Alexey Menshikov has spent the last year developing and extending his original Spektral ideas. The result is Spectrum Worx, and the most obvious change is that it's modular, with enough room for up to 16 modules to be placed in the virtual rack.

Modules are added to or removed from slots by right-clicking, and you can also bypass individual modules, which is very useful during sound creation, to see what effect each one is having on the final sound. It's also possible to click and drag modules into any other empty slot, and I found it useful to leave gaps between each module while developing new sounds, to make it easier to drop additional ones in later on. Presets can be loaded and saved using the familiar Windows dialogue windows, while an additional Preset Browser allows you to quickly audition any of the supplied presets with a double-click on your mouse.

Right-clicking anywhere over the main controls launches a further control menu with various settings such as the number of FFT (Fast Fourier Transform) bands from 128 to 2048, Window shape, and Overlap factor (all fundamental parameters for the Fast Fourier Transform analysis). Also available is the Debug Spectrum window — a simple spectrum analyser which helps to unravel what the presets are doing in the spectral domain.

Modules & Modes

Version 1.0 of Spectrum Worx is bundled with 45 modules, and more will be added in future versions. There are currently 18 in the Two-ins category, eight in the Phase Vocoder section, and a further 18 in the Effects category.

As their name suggests, the Two-ins modules require two inputs: the original sample and a modulation sample or side-chain signal. You can use the Load Sample button and the Sample Browser to choose a suitable sample, either from the supplied set in the Samples folder or any mono or stereo WAV or AIFF file, although I found you can also work without any sample loaded and still get a wide range of pleasing effects. The Info Bar shows the sample bank number, the sample name and its duration (up to eight banks are available, as chosen by the Sample Bank selector on right-hand side of the Info Bar), while underneath you can find the current preset name and any attached comments.

Modulation samples loop continuously in the default 'Sample stream on Load' mode, but when using obviously cyclic modulation samples such as a drum loop, the Trigger and Gate modes are more appropriate. To use these you set up a MIDI track, point its output at Spectrum Worx, and use a MIDI note message to either restart the loop on demand (Trigger mode) or start and stop it using MIDI Note On and Off commands (Gate mode). This lets you synchronise the modulation to your song.

Modules that require samples for modulation (such as the Vocoder in this preset) can synchronise their start time via the host application, using MIDI note commands. Spectrum Worx is also a 'skinnable' application — this is the Virus skin.Modules that require samples for modulation (such as the Vocoder in this preset) can synchronise their start time via the host application, using MIDI note commands. Spectrum Worx is also a 'skinnable' application — this is the Virus skin.

There are also four modes for the Spectrum Worx plug-in itself. The default and most often used is 'Stereo ext. 2+1 In 2 out', which takes stereo input and mono modulation signals and processes a stereo output from them. However, you can switch to 'Mono ext 1+1 in 2 out', which only processes the left channel of the input signal, for lower CPU overhead, while the 'Sidechain mono 2 in 2 out' mode abandons the internal sample bank, instead using the right-hand channel of your stereo input as a modulation signal, and 'Sidechain stereo 4 in 2 out' processes stereo signal and modulation signals in those hosts that support routing four inputs to a plug-in.

I suspect most users will stick with the default Stereo In plus Internal modulation mode, since switching to another mode entails restarting the plug-in and sometimes the host application as well, and the '4 in 2 out' mode may crash some hosts, including DirectXier and Wavelab. However, it is worth persevering with the side-chain options, as they can give quite different results from using a static sample, even with the same preset.

Around The Modules

Of the 18 Two-ins modules, the first batch are described as morphers, and even from the very first Blender module, most users will be in largely unfamiliar territory. It's described in the manual as performing 'a linear blend in the frequency domain of magnitudes and phases of Source to Target', and has just two controls for Magnitude and Phase. With a few tweaks and a suitable sample loaded into the bank you'll soon be producing a wide range of vocoder-like sounds. Morphine provides an 'adaptive spectral blend', while Turnupeer is another adaptive interpolation blend module specially recommended for pads or textures, and both provide results in the same ball park as Blender.

As we continue through the Two-ins we reach the strange metallic and reverb-like transformations of Uniform (an old favourite from the Spektral Morpher of the Spektral plug-ins). Pitch Trans provides more obvious results, with pitch-shifting of up to ±48 semitones, but beyond this point we enter the world of the operators, with Convolve, Math, Combine and Inserter, all of which manipulate the magnitudes and phases of the two signals in various ways and have a wide range of totally different-sounding 'operators' (modes or algorithms).

Vocoder1 is a basic and easily understood vocoder with a single Brightness control, but then we're plunged back into the unworldly whimsy of such modules as Shapeless (frequency shaper), Vaxateer, Burrito and Ethereal (described as three compositional tools), Tai and Coloripher (spectral interpolation tools), Pitch Follower (a familiar name, but it's still a very unusual effect in Spectrum Worx), and Denoiser. Most are very difficult to describe, not least because a slight control movement often changes the sound completely, and I suggest you download the demo version to hear them in action for yourself.


Many of the controls provide hugely different results as they are altered, so thankfully MIDI automation is available within those host applications that support it, to take advantage of this flexibility. Since there are 16 possible slots and up to five controls to each one, Delaydots have implemented a scheme of 80 parameters labeled 'Slot XX cc YY' where Slot XX can vary from 0 to 15, and cc YY can vary from 0 to 4.

You can also directly assign any MIDI controller number to any parameter by right-clicking on it and using the Assign CC function (which also helpfully displays its Slot and CC number), so you can automate Spectrum Worx from a hardware controller for real-time manipulation. The system worked well for me in Cubase SX, and further multiplies the creative possibilities.

Phase Vocoding & Effects

The eight modules in the Phase Vocoder section use short portions of the original sample to create the FFT, converting phase to frequency and back again, with various options for such things as pitch-shifting and spectral exaggeration along the way. Some work best with the Phase Vocode A module at the start of the chain to transform phase to 'true' frequency and leave magnitudes untouched, and then the Phase Vocode B module at the end to transform frequencies back to phase before further treatment, but there are no real rules. In general I found this group provided more predictable (but still radical) results, and I particularly enjoyed the two highly experimental Hideki Takuramu modules with their Warp and Hold controls, which perform pitch transformations and sample-and-hold effects respectively.

The Effects are perhaps easier to understand, comprising among others pitch-shifting, spectral gating, filtering, smoothing and sharpening, and band-pass filtering with an envelope follower (a simpler version of the Extractor from the original Spektral plug-ins). Transient Extractor attempts to extract the pitch and noise components of incoming sounds with a threshold control, while Slew Limiter provides weird metallic enveloping once you pull its limit control down below about -50dB.

Other offerings include various spectrum modifiers — Shifter shifts the spectrum left or right on demand, Mirror reflects the spectrum relative to the chosen filter frequency, Randomiser chops the spectrum up into chunks and interchanges them a number of times, Quantiser is similar to graphic pixellation but in the spectral domain, Wobble is LFO-controller ring modulation, and Waka's Swappah selects three bands from the spectrum and swaps them around.

Spectrum Worx's Phase Vocoder module options may be more familiar than some of its other effects, but there's still plenty of potential for weirdness.Spectrum Worx's Phase Vocoder module options may be more familiar than some of its other effects, but there's still plenty of potential for weirdness.

In Use

As you've probably gathered, explaining what each module does is somewhat difficult, and even when you can, the audio results can still be highly unpredictable. There are plenty of mathematical explanations included in the manual for those who are interested, but once you start chaining modules together the strangeness and charm multiplies still further. Although it's helpful to open the Debug Spectrum Window to see what's happening in the spectral domain, this is only really instructive with single modules, and even then not very often!

Thankfully you really don't need to understand what each module does, or to try to guess how they will interact — the fun is in exploring for yourself and seeing what happens. To give you an idea of the possibilities, using a straightforward acoustic drum loop input signal and nothing in the sample bank I managed to create springs, robotic voices, metallic coughs, elastic twangs, chimes and ringing tones, toy pipes, drone rhythms and futuristic wasps, as well as unearthly sci-fi backdrops that bore little relation to the source material. This unpredictability is what appealed to me about the original Spektral plug-ins, but this time round, the permutations are infinitely more complex, and while I once again enjoyed myself, it can also be frustrating, since it's very easy to end up with either an unmusical noise or total silence during the creative process.

For this reason, Spectrum Worx is shipped with over 100 factory presets, including a number of Basic patches containing only one (or occasionally two) modules, which are intended to illustrate some of the results you can achieve with particular modules. Some of the other examples in the Complex Effects folder such as drum machines and more advanced vocoders employ anything up to six modules, but I'm not convinced that 16 slots will ever be needed, so perhaps Alexey should consider a half-size 'compact' option with just eight slots.

As you might expect from previous Delaydots offerings, the presets contain dozens of distortion possibilities from the ridiculous to the sublime, but there's also radical pitch-shifting, vocoding that runs from from ethereal choirs to wicked droids, whippy envelope-following filters, flangers that can turn your head inside out, sample-and-hold reverbs, through to electronic drums and even loop-driven drum machines.

Final Thoughts

One obvious competitor to Spectrum Worx is Izotope's Spectron, which also processes in the spectral domain and is exactly the same price, but which has a far more elegant graphic interface, is easier to use, and has a good set of additional spectral delay and pan options. On the other hand, Spectrum Worx offers much more extreme sonic possibilities, is also far more versatile, and generally incurs lower CPU overheads — most presets took about 6 percent of my P4 2.8GHz processor.

Those into total sonic destruction will love Spectrum Worx, but it's also capable of subtlety if you're careful and patient. For those who want instant results there are a wide variety of presets already available, and no doubt more to come from inveterate sonic explorers. Although the interface is simple in concept, and the results amazingly versatile, the majority of the modules can't be described as particularly user-friendly, and may prove impenetrable to some. However, for those who persevere the rewards may be sounds that you've never heard anywhere else before.

Published August 2004