This one's different. In the crowded world of plug-in virtual instruments, Steinberg's Plex joins the likes of Native Instruments' Absynth, Antares' Kantos,

This one's different. In the crowded world of plug-in virtual instruments, Steinberg's Plex joins the likes of Native Instruments' Absynth, Antares' Kantos, and Green Oak's Crystal in offering something that looks, feels, and sounds unique. Plex is the brainchild of Wolfgang Palm, inventor of the PPG Wave synthesizers in the 1980s. But Plex is not a software version of the Wave or any other vintage synth; instead, it offers a completely different algorithm, called Restructuring Synthesis, to analyze and resynthesize a library of sampled sounds. Plex's user interface is a bit unusual, but the layout is intuitive and can be mastered in short order. No demo version is available, though you can download audio examples from Steinberg's Web site.

Plex is a VST Instrument plug-in, and accordingly, performance will depend on your VST host software as well as your computer's processing speed. For this review, I tested Plex in Logic Platinum 5.3 and Cubase VST/32 5.1 on a Mac G4/800 PowerBook running Mac OS 9.2.2. The audio interface was an RME Multiface. I was able to achieve low latency along with low CPU usage in both hosts.


Restructuring Synthesis begins with a collection of 98 preanalyzed sounds ranging from acoustic-instrument samples to complex synthetic waveforms. The analysis process is not part of the Plex plug-in, and in any case, it's too complex to perform in real time; therefore, you can't use your own sounds in Plex. But because a Plex Preset combines components from three different sounds, you have 941,192 combinations with which to work (check out the EM Web site for MP3 examples of several Presets).

The analysis that Plex uses splits each sound into Top, Base, and Filter components. The Top and Base components are the upper- and lower-frequency spectra of the sound — much as it would sound through steep highpass and lowpass filters. The Filter component is a time-variant analysis of the sound's spectral evolution. You can think of the Filter component as a series of snapshots or frames of the sound's frequency spectrum as it evolves.

Plex's Filter component is probably the most difficult to grasp if you're coming from a typical subtractive-synthesis background. When you sweep through the frames of a Filter component, you don't usually get results similar to changing the cutoff frequency of a typical low-, high-, or bandpass synthesizer filter. It's more like moving through different settings of a multiband graphic equalizer. As you might imagine, some very unusual sounds result.

Plex's Sound Palette holds a maximum of 33 of Plex's 98 preanalyzed sounds (see Fig. 1, left). Right-clicking (Control-clicking on the Mac) a position in the Palette opens a menu from which you can select the sound for that position. The Palette contains icons for the Top (green), Base (red), and Filter (yellow) components. Dragging an icon to a position on the Palette selects the corresponding component of that sound. Thoughtfully, one of the provided sounds is silence, which, if you include it on the Palette, will allow you to audition the Top and Base components individually and without any filtering. The Sound Palette might seem superfluous because each Preset uses at most three sounds, but it allows you to quickly create variations of a Preset by simply moving the component icons around. The MP3 file ReZound is an example of what that can produce.


Each component (Top, Base, and Filter) has its own LFO and ADSR envelope generators. Those control the level of the Top and Base components in the mix. For the Filter component, they control the frame position and provide many alternatives beyond the original spectral evolution of the analyzed sound. The LFO and ADSR setups are a bit out of the ordinary and contribute a lot to Plex's uniqueness, so let's take a quick look at each.

Fig. 2 shows Plex's LFO controls. An LFO pattern always consists of 16 steps, each of which has a range of 16 values. The waveform buttons below the Wave display call up preset patterns, which you can then modify by clicking in the display. You can use the Smooth knob to smooth the transition between steps; smoothed is good for modulation effects, whereas unsmoothed is good for step-sequencing effects.

The LFOs can be free-running or synchronized to the host song's tempo. When free-running, the Speed knob's scale is logarithmic, with a range of 0 to 100. It would be useful to have it calibrated in milliseconds like the Delay knob, which sets a fade-in time of a maximum 11 seconds for the LFO. In a nice touch, you can link the LFOs by clicking the Master button; the settings of the Master LFO then apply to all three sound components.

Conspicuous in its absence is any provision to apply the Top and Base LFOs to pitch. Although a Pitch LFO is in the Global section, it does not offer the step-editing features of the individual LFOs, and it applies equally to both components. Except for octave transposition, there is no way to tune the Top and Base components separately — for example, to an interval of a fifth. Those both seem like severe limitations that would have been easy to avoid.

Fig. 3 shows Plex's ADSR controls. The first thing to notice is that two ADSR shapes are displayed. The blue one applies to the high end of the MIDI note range, and the gray one applies to the low end. The ADSR pattern morphs from the gray to the blue shape as you move from the low to the high end of a standard five-octave MIDI keyboard.

You can edit the ADSR settings by dragging on the numbered handles in the graphic display or by using the sliders below the display. For each setting, the left slider controls the low envelope and the right slider controls the high one. Having separate ADSR settings allows you, for example, to make the Base component's level increase while the Top component's decreases as you move up the keyboard. Because the Top component of most sounds tends to be quite buzzy in the upper registers, that feature is very handy. (Transposing it down a couple of octaves would be another alternative.) You can edit the curve of the attack, decay, and release segments by dragging between handles, but unfortunately, the same shape is applied to both the high and low envelopes.

The ADSR section contains several other important settings. You can set the effect of MIDI Velocity on the envelope amount and attack time. For the Top and Base components, you can also set the sample-playback start position as well as the effect of Velocity on that position. You can transpose the Top and Base components up or down two octaves, but (as I mentioned previously) you can't tune them separately. Finally, you can set an offset for the frame position in the Filter component, which, together with the Amount control, allows you to restrict the Filter motion to a narrow range of frames. With the amount set to zero, the high and low Offset settings provide a form of filter key-tracking.

The final set of Plex controls is in the Global section (see Fig. 4). They are the Pitch LFO settings mentioned earlier, Pan controls (including randomization on a per-note basis), MIDI Modulation-Wheel Destinations (which includes most LFO, ADSR, and effects parameters), and settings for a feedback delay line that has short (flange and phase) and long (echoes as long as 2 seconds) delay modes. All Plex controls can be assigned to MIDI Control Change messages. The current assignments are shown on the Plex back panel, which you can access by clicking the Steinberg logo, and the assignments can be customized by editing a separate file with a text editor.


Plex's preset memory is organized in three levels: Banks, Instruments, and Groups. Groups hold 16 Presets each, and four Groups make up an Instrument. Instruments are held in Plex's active memory, meaning all their Presets are directly accessible from Plex's front panel, and individual Preset elements can be moved from Instrument to Instrument. Banks are disk files holding eight Instruments each. Therefore, a Bank potentially holds 512 Presets, though not all Presets need be filled.

On the right side of Fig. 1, you'll see Plex's Preset-selector section. Group A of the first Instrument of the factory bank is shown, with its 16 Presets displayed by name in the curved column below the Group-select buttons. Each Preset includes its own Sound Palette with whatever sounds the author has chosen to include. The most obvious modification of any Preset is to move the Sound-Palette icons around. That preserves the Preset's ADSR and LFO settings (and therefore any dynamics and motion programmed into the Preset) while changing its timbral character.

The narrow column to the right of the one containing the Preset names contains a single entry that refers to a Preset by Group and number. Clicking in that column is Plex's other quick-change programming feature; it applies everything except the Sound-Palette settings of the Preset in the clicked position to the currently selected Preset. Think of it as the converse of moving the Sound-Palette icons around; the timbral elements remain the same, whereas the dynamics and motion change. Those two features — swapping Sound-Palette components and swapping everything else — make creating new Presets a breeze even if you never touch the individual ADSR, LFO, and Global settings.

Plex comes with a nearly full factory Bank containing Presets by Wolfgang Palm and others by well-known German sound designers Hubertus Maas and Peter Gorges. The Presets in the first Instrument provide a good introduction to Plex's range of sounds. Group D of that Instrument contains a handy selection of Presets from which to start your own exploration of Plex's Sound Palette. The last two Instruments of the factory Bank are also useful for that — each Preset uses the Top, Base, and Filter components of the same sound with the ADSR set to replicate the natural evolution of the sound and with no LFO applied.

Factory Instrument 2, called Rhythm City, offers just about every variation on LFO and delay-generated rhythm you can imagine. The emphasis is on combined pads or bass sounds with percussion. You can get a lot of mileage from those Presets by swapping their settings, thereby applying the rhythm of one Preset to the sounds of another. The MP3 file RhythMorph is an example of that process.

The remaining four Instruments contain demo sounds from each of the sound designers. Apparently, their goal is to illustrate the use of different combinations of Sound-Palette components in the standard sound categories — basses, pads, piano-like, synth, vocal, and so on. The Presets in those Instruments offer a great starting point for building Presets in their category by moving the component icons around.

Plex's unique synthesis architecture makes it a very attractive buy. At $249, it is definitely at the high end of the price spectrum for plug-in synths, but you won't find exactly these sounds anywhere else. The interface is especially well designed for modifying existing Presets. Building your own from scratch is also not difficult once you've grasped what Plex is all about. The Plex manual and factory Preset Bank are all you really need to get a handle on this synth. A trip to Steinberg's Web site for a listen to the Plex demo songs is certainly in order.

Minimum System Requirements

Plex 1.0

MAC: G4/400; 180 MB RAM; OS 9.1/X; VST-compatible host

PC: Pentium III/600; 180 MB RAM; Windows 98/2000/ME/XP; VST-compatible host


Plex 1.0 (Mac/Win)
software synthesizer


PROS: Unique synthesis architecture. Large factory palette of preanalyzed sounds. Convenient Preset-transformation features.

CONS: Sound sources can't be tuned separately. Limited pitch-LFO settings.


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