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Lexicon Vortex

Audio Morphing Effects Processor By Paul White
Published June 1994

Lexicon's new Vortex effects processor takes the concept of video morphing and applies it to audio effects. Paul White takes it for a spin.

Vortex: it sounds as though it could be a toilet cleaner or maybe a Dr Who nemesis, but in reality, it's an attempt by Lexicon to give standard delay and modulation effects a new twist, by adding a high degree of performance control. Vortex is designed primarily for live performance, with performance control applied by means of footswitches, foot pedals, and the envelope of the sound being treated. There's no MIDI and, compared with most dedicated effects units, a limited degree of programmability. What makes the Vortex stand out from other units offering dynamic performance control is its morphing ability, whereby one effects patch becomes another over a period of time. This isn't the same as crossfading, because the effects parameters actually change, causing the first effect to turn into the second. Depending on the effects at either end of the morph, the intermediate stages can either be subtle and gliding, or — as is sometimes the case — two seemingly mild effects can pass through a transition phase of overmodulated hell that sounds not unlike an endangered sea creature trying to escape from a washing machine during the maximum spin cycle!

Morph For Your Money

The Vortex is based around two banks of 16 presets, though a further two banks of user modified effects may be set up and stored. Each effects comprises modulation and delay elements, and all share a common set of 16 parameters, selected by means of a rotary switch. Where morphing is required, it occurs between the selected effect in Bank A and its similarly numbered counterpart in Bank B. This means that when working with the presets, you are limited to morphing between the effects pairs provided, although in the user banks you can either store copies of the presets in different positions (to permit new morph combinations), or edit the presets by varying any of the 16 available parameters. The rate at which a Bank A sound morphs to a Bank B sound (and vice versa) can be set by the user up to a maximum of 10 seconds, and values can be set for the A‑B morph independent of those assigned to the B‑A morph.

Morphing can be initiated by means of a front panel button or from a footswitch, though there's more to performance control than morphing. Several of the effects include a degree of envelope sensitivity, allowing playing intensity to control such things as modulation rate or echo intensity. Additionally, if you're capable of playing with each foot on a different pedal, a standard volume pedal may be used to vary one of the effects parameters in real time. Any of the echo or delay‑based effects can be set up by means of a tap‑tempo button on the front panel, making it very easy to synchronise the tempo of the delays to the music being played.

Into The Vortex

The Vortex shares the same shallow 1U rack case as the Lexicon Alex and JamMan, drawing its power from an external PSU. The rear of the unit has unbalanced jacks to accommodate stereo inputs and outputs, and four further jacks for foot controls. Jack A/B is connected to a relay switch, allowing external devices, such as guitar amp channel switching, to be changed from the Vortex front panel or from the A/B footswitch. A double footswitch unit is included with the Vortex, as is a stereo jack lead, and switch control is provided over A/B morphing, Tap, Bypass and Step. Two double footswitches are necessary if simultaneous access to all these is required, and adhesive labels are provided so that the footswitches can be identified. A further stereo jack accepts the input from an optional volume pedal, to provide real‑time control over the selected parameter.

The signal path of the Vortex allows for true stereo processing, where each channel of the input is processed via a different route, and this is the best option for use with stereo keyboards. With guitars and other mono instruments, only the right input should be used. The dry/effect mix is stored as part of an effects program, which means it's easiest to use the Vortex in line with the signal to be processed, rather than via an effects send/return loop. Of course, the dry signal can be turned down and the unit fed from an effects send, but then the dry mix has to be set manually from the mixer, and will vary from effect to effect.

Two seemingly mild effects can pass through a transition phase of overmodulated hell that sounds not unlike an endangered sea creature trying to escape from a washing machine during the maximum spin cycle!

As with the other processors in the series, the front panel of the Vortex is disarmingly simple, kicking off with an input level control and a very simple level meter comprising green 'signal present' and red 'overload' LEDs. The Pedal/Tap button is used to directly enter the tempo of a delay effect; the delay time is then either the time between button presses or a sub‑division of that time if your choice exceeds the maximum delay time available. The delay time may also be tapped in via a footswitch, and if a volume pedal is connected, the Pedal/Tap button assigns pedal control to any selected parameter, except Echo 1 and Echo 2 delay times.

A simple 16‑way rotary control is used to select a parameter for editing from the list surrounding the Value knob to the right of the display. The Clear button allows user memory pairs, or register pairs, as Lexicon call them, to be cleared, so that they are not included in the chain of patches accessible from the Step footswitch. This is a useful feature for live use, where a chain can be set up to be stepped through for the required effects only.

The Store function enables revised effects to be stored in any of the user locations. The system used is simple, if a little unconventional: set up an effect, press and hold the Store button, select a suitable user memory, and then release the Store button.

The display window shows two digits in the range 1‑64, and also includes status LEDs, to show whether effect A or B, or a parameter value is being viewed. When a pedal is being used, the pedal position shows up as a change of value in the display window. If the decimal point is lit, it means the current effect has been edited and not stored. The A/B switch moves you between Effects bank A or B, while the Register/Preset button selects user or preset effects. Finally, there is the effects selection knob, which is used to access the current preset or user effect. The 16 preset effect titles are printed around the switch, and a description of the individual effects is provided in the sidebar.

In Use

Most of the preset effects are pretty standard when heard in isolation, and fall into the categories of stereo echo, chorus, flange and similar effects. Some of the algorithms also include an element of detuning, but on the whole, most of the effects sound very familiar. Having said that, the effect algorithms are quite complex and it is possible to program a whole range of quite sophisticated effects, though the convoluted routing within the algorithms usually means that you don't always know what to expect when you change a parameter.

Having footpedal control over a selected effects parameter is useful, as is the envelope following function, but the morphing aspect of the Vortex has the most creative potential and, I feel, is also the least well implemented. Having to push a footswitch every time you want to create a morph is very tedious, especially as the included footswitch is one of the least tactile I've ever encountered — the only way I could tell whether I'd hit it was to listen for the click of the internal A/B relay. A vast improvement would have been the option of triggering a morph from the attack of a note or chord, or of pedal control over morphing (rather than just over one effect parameter). Better still, some form of simple MIDI trigger would have made the unit far more useful in the MIDI studio.

Leaving aside my criticisms of the operating system, it's time to comment on the subjective nature of the effects available. The delays and choruses are warm and musical, while the rotary speaker simulation winds up and down in speed as you morph, pretty much like the real thing. Having said that, I found the preset pairs nearly all produced very insipid morphs, and in the context of a mix, it was sometimes hard to tell that the effect had been changed at all. In most cases, the delay pattern changes a little or the modulation intensity increases, but that's about all. Of course, when you come to select your own effect pairs and edit a few parameters, you can arrange to move between two very different effects, but as mentioned earlier, the results are sometimes quite different to what you might expect. If you find the interim stages too off‑the‑wall, you can change the morph rate, or the effects at either end, but the only reliable way to find out what you're going to get is to try it and see.


As a performance effect, the Vortex is a really good idea, though I feel it has been hamstrung by the need to make it fit into the same box as the rest of the Lexicon low‑cost range, with the same controls and the same selling price. It's particularly unfortunate that no MIDI facility was included to either trigger or control the morphs using MIDI controller information.

Good points are that the morphing can be supplemented by real‑time pedal control (albeit of only one selected parameter), and that there is envelope control over some effects parameters. Most of the effects are musically useful, whether for setting up a Shadows‑style echo or an Andy Summers‑style chorus, and only the dubious 'Bleen' resists all attempts to find anything useful for it to do. I don't think the Vortex breaks any new ground as an effects unit, other than in its approach, though the unusually complex algorithms enable you to come up with a few fresh variations on what might otherwise be considered overused effects. If Lexicon take the concept further, maybe we'll see more sophisticated morphing processors turning up over the next year or two.

If you do a lot of live playing and don't mind tap‑dancing on pedals, then the Vortex will probably suit you down to the ground, but in the studio, I think there's already too much to concentrate on. Check it out and let me know what you think.

Those Morphing Effects In Full

  • REFLEXION: A detuned stereo echo effect, where the amount of detuning is controlled by the signal envelope. In the Bank B version, the envelope detuning effect is more moderate, and the echo rhythms are different.
  • ATMOSPHERE: A combination of stereo echo and vibrato, where the envelope controls the vibrato speed. The Bank B version uses a different algorithm, which combines tuned resonators with echoes and modulation. Envelope increases the modulation rate as the input signal increases in level.
  • ORBITS: This pair of patches provides fast and slow rotary speaker/chorus sounds, where the morph rate sets the wind‑up and wind‑down time of the rotary effect. The pedal isn't used in the preset, but an edited patch could have the pedal assigned to rotor speed.
  • CENTRIFUGE: A combined echo and rotary speaker patch, where the signal envelope affects modulation rate and resonance. The Bank B version uses the same algorithms, but with different parameters — the louder the input signal, the slower the modulation rate.
  • AEROSOL: Modulation followed by echo with feedback from two different taps, which means that the echoes get more complex as they decay. The Bank B version uses a slightly different signal path, where Envelope controls the feedback level so that loud signals have only a single repeat.
  • MOSAIC: A complex mix of echo followed by pan and modulation, then more pan. Envelope decreases the panning rate, while in the Bank B counterpart, a series combination of two multi‑vibrato and echo modules is used. Here the envelope of the input decreases modulation depth.
  • MAZE: Here a mono input is panned into two echo modules routed left and right, and also via a stereo modulator block. Envelope decreases the panning speed. In the Bank B version, the effects are used in parallel with envelope detuning. This gives note attacks a hint of flanging.
  • DUO: Feedback echo in one channel with two vibrato blocks in the other. Envelope increases the effects level. The Bank B version creates a stereo vibrato treatment from one input and a stereo delay from the other, with envelope increasing the vibrato rates.
  • DEJA VU: Echo, pan and stereo glide combine with panning; Envelope decreases the delay level. The same arrangement is used in Bank B, except that here Envelope decreases the input feedback mix, making the echoes repeat for longer on quieter sounds.
  • CHOIR: This effect introduces the Haas effect block (which may just be pre‑delay) followed by multi‑chorus and two helpings of echo. Envelope decreases the chorus depth. In the Bank B department, the same blocks are used, but in a different order, with Envelope still decreasing the chorus depth.
  • SHIMMER: A cross‑resonance modulator feeds a stereo tremolo, which in turn feeds two echo blocks panned left and right; Envelope increases the tremolo rate. The Bank B version uses a resonator instead of the cross‑modulator, and Envelope is used to increase the modulation speed and decrease the resonator tuning.
  • SWEEP: Stereo glide combined with stereo echo produces a dynamic detuning effect with echo. Envelope decreases the glide depth. In Bank B, the stereo glide block is replaced by a multi‑vibrato block, and Envelope decreases the vibrato depth.
  • SHADOW: Despite the complex mix of stereo echoes, top‑cut filters and X‑Res modulation, what we have here is a Shadows tape echo simulation, where envelope decreases both the echo feedback and the echo output level. Bank B is similar sounding, although it uses a totally different algorithm fed via a low‑pass filter, where Envelope raises the cutoff frequency.

v CYCLOID: A stereo echo treatment where the tone of the signals feeding the echo blocks is continually varied. Envelope raises the filter cutoff frequency. The Bank B version places the filter block after the delays, and Envelope is used to increase the speed of the filter modulation.

  • BLEEN: What can I say? A resonator, followed by amplitude modulation, followed by echo and pan. This has a nasty ring modulator tone about it, where Envelope increases the modulation rate and shifts the resonator tuning downwards. Version B sounds just about as evil, with Envelope controlling detune. The best thing about this patch is the name.
  • FRACTAL: More echo, pan and glide, which creates a novel stereo effect. Envelope decreases the feedback, so loud signals increase the amount of input signal in the mix, while softer signals create more feedback. The same algorithm is used for both A and B versions, but with different parameters.

Effects Parameters

  • Echo 2
  • Echo 1
  • Envelope
  • Morph A/B
  • Echo FX Level
  • Mod FX Level
  • Output
  • Mix
  • Resonance 2
  • Depth 2
  • Rate 1
  • Resonance 1
  • Depth 1
  • Rate 1
  • Feedback 2
  • Feedback 1


  • Simple to use.
  • Friendly Tape Tempo delay facility.
  • Unique morphing concept.
  • Real‑time control via pedal and sound envelope.


  • Clumsy control over morphing.
  • No MIDI real‑time morphing control.
  • Dreadful footswitch.


An novel and individual live effects unit that feels a little out of place in the studio. Best suited to the gigging player who also records, and who doesn't want to be bothered with MIDI control.