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Native Instruments Absynth

Stand-alone/Plug-in Software Synth For Mac By Paul Ward
Published December 2001


Released last year as a web‑only download from Rhizomatic, the ground‑breaking Absynth is now part of Native Instruments' product line, and can be used as a VST instrument plug‑in.

Native Instruments are one of the major players in the world of virtual instruments. From the innovative modular synthesis of Reaktor to B4's faithful rendering of classic Hammond growls, software from the NI stable rarely disappoints.

Absynth sees Native Instruments taking on technology that originally appeared during 2000 as a download‑only purchase written by software company Rhizomatic. The software took an interesting, novel approach to software synthesis, with its semi‑modular architecture, wave‑shaping capability, waveform drawing, and 68‑point envelopes. Rhizomatic have now joined forces with Native Instruments, where the designers will reportedly continue to refine and develop Absynth.

Absynth is a Macintosh‑only software synth that will run either as a stand‑alone application or as a plug‑in, being compliant with VST 2.0, MAS, DirectConnect and ASIO standards. During the course of this review, I tried Absynth as a stand‑alone application and as a VST 2.0 plug‑in under both Steinberg Cubase VST v5 and Emagic Logic Audio Platinum v4.7.3, and it performed happily with no discernible compatibility problems. Minimum system requirements amount to a Mac G3 300MHz, Mac OS 8.6 and 64Mb of RAM. For details of the review machine, see the 'Test Spec' box elsewhere in this review.

Installation is simplicity itself — you just tell the program which plug‑in standards you'd like to use, and the installation routine takes care of the rest. On first running, you'll be asked for the installation CD to be inserted and to enter your serial number, but that's as tough as it gets.

The audio buffer and sample playback rate may be set for the stand‑alone version of the program to optimise use with specific soundcards. Vector size determines the rate at which the LFOs and envelopes will update, and also the timing precision when using Absynth as a plug‑in. The trade‑off, as usual, is between performance and CPU load. Apple Sound Manager, ASIO, DirectConnect and MAS audio output are supported, as are both FreeMIDI and OMS for MIDI connectivity.

Absynth Engine

Absynth's Giger‑esque Patch editing window.Absynth's Giger‑esque Patch editing window.

When Absynth is invoked as a plug‑in, the so‑called Absynth Engine application automatically loads up in the background. Simple patch selection and the loading and saving of Banks can be undertaken from the host plug‑in window, but attempting to access any deeper editing features swaps control to Absynth Engine. If this sounds a little confusing, it does quickly becomes clear in use — although I would have preferred things to be self‑contained within the plug‑in itself. Unfortunately, this split way of working also means that the standard VST load and preset select menus don't work, which is somewhat irksome. Up to eight plug‑in instances of Absynth may be loaded at any one time, and a row of numbers at the top of the Absynth Engine control panel highlights the currently active instance.

All of the usual file‑handling options are provided (Save, Load, Save As...), with the ability to import/export individual Presets, or revert to the last saved version of a Bank. Absynth Engine permits only one Bank to be loaded at a time and this Bank is shared between the eight plug‑in instances.

The plug‑in window contains an on‑screen keyboard, with 'sprung' pitch‑bend control and key hold capability, and MIDI controller slider bars. The slider bars act as on‑screen controllers (transmitting MIDI data to the sequencer) and will also reflect external MIDI input. Movement of these sliders can also be recorded under standard VST plug‑in automation. A sustain feature will hold notes played over MIDI until the control is unlatched or a MIDI sustain message is received. Further controls allow the setting of velocity (for the on‑screen, virtual keyboard), polyphony, volume, panning, transposition and tuning, and a Panic button is provided to clear stuck notes or delay repeats. The Bank, selected Preset and MIDI slider settings are all stored along with the host sequencer's song data.

Clicking on one of the six editor buttons in the top right of the plug‑in window brings Absynth Engine to the fore and presents the chosen editor window. A navigation bar lists the Absynth edit windows: 'Main', 'Record' (available only when Absynth is used as a stand‑alone synth — see the 'Absynth As Audio Recorder' box elsewhere in this article), 'Patch', 'Wave', 'Env' (for envelope editing), 'LFO', 'MIDI' and 'Effect'.

Patch Window

The Wave editor.The Wave editor.

The Patch window (shown above) is where the fundamental structure of the Preset is constructed; here you turn on or off each of the 12 DSP modules (three oscillators, four filters, three modulators, one waveshaper and one effect) and set parameters pertaining to each module. 'Tubes' connecting the modules give an idea of the signal path, but there is no clear indication of the direction of signal flow, which could confuse newcomers. Each plug‑in instance creates its own stereo audio feeds into the host program — it is not possible to create extra audio outputs.

Each of Absynth's three discrete 'channels' consists of an oscillator, a filter and a modulator. An option for the three channel balance sliders in the Patch window forces them to automatically adjust when any one of them is moved to produce a total output gain of 0dB. This is a very thoughtful inclusion which makes balancing between the channels much easier, and ensures that the synth's audio output is always optimised. Each oscillator is capable of generating waveforms in one of four modes: 'Single', 'Double', 'FM', or 'Ring Mod'. 'Single' is the simplest oscillator mode, where a solitary waveform is produced which can then be passed on to subsequent modules. 'Double' creates two waveforms with the ability to individually adjust balance, waveform, tuning and phase for each wave (interestingly, according to NI, utilising a single oscillator in Double mode is more processor‑efficient than two oscillators in Single mode). As you might expect, 'FM' provides a two‑oscillator implementation of FM synthesis. It's worth noting that the oscillators are of a single‑cycle nature (that is, they will not play samples).

Waveforms are chosen from a 'Wave Popup' menu, where you're offered a series of factory presets (including all the most common waveforms, with useful variants) and up to eight user‑generated waveforms. User waveforms cannot be swapped between Presets, but NI say that they do intend to implement a method of allowing users to build waveform libraries in a future release.

Oscillator frequency may be adjusted in one of four modes: by semitone note transposition, frequency ratio, frequency in Hertz, or by MIDI note number. Strangely, if you elect to use Hertz or note numbers, you forgo the ability to use LFOs or pitch‑bend on that oscillator, although envelope modulation is still available. This seems an odd restriction, and caught me out during editing. The phase of each oscillator is switchable, and a Phase Offset control is provided, which is particularly useful in FM voicing.

Absynth offers a good selection of filters, including six, 12, and 24dB‑per‑octave low‑pass, six and 12dB‑per‑octave high‑pass, band‑pass, notch and comb types, with variable resonance where appropriate. Interestingly, you can also switch the filter between mono/poly allocation, which makes it possible to emulate some old synths that shared a single filter across all voices.

The Modulator module currently has only one mode — ring modulation. Its controls are similar to those found in the oscillator module. Balance between the input and modulated signal is variable.

The 'Waveshaper' module takes an input waveform and uses its own waveform to distort it. Input and output volumes are adjustable, which is important, as the results of wave‑shaping are sensitive to the amplitude of the input. This is a powerful tool, not least of which because the distorting waveform can be drawn in the wave editor (of which more in a moment). The module will function in either mono or poly modes (one for each voice). I found the results to be strangely alluring, particularly in poly mode where I found I could easily achieve tones reminiscent of old guitar synths.

Wave Editor

The Envelope editing window.The Envelope editing window.

The Wave editor is where much of Absynth's strength lies. Two editing modes are provided. In 'Waveform' mode you have the ability to 'draw' a waveform in the time domain; in basic terms, the more squiggly the waveform you draw, the more high‑frequency content it will exhibit. In 'Spectrum' mode you have access to the amplitude and phase of the first 64 harmonics of the waveform (although Absynth retains all harmonics above these 64, you can't edit them). These two edit modes may be combined, providing a fine degree of control over your waveforms. It's possible to load another waveform from the factory or user presets to act as a starting point.

Drawing a new waveform is a simple click and wobble of the mouse away. Curve‑ and line‑drawing tools are available and may be combined in the drawing of a single waveform. Once drawn, the waveform may be mistreated by a number of shaping tools and processes, including the adjustment of both amplitude and offset around the zero point. By choosing the 'stretch' tool and setting left and right delimiters, you can 'warp' the amplitude of the waveform. Waveform drawing and mangling may all be undertaken glitch‑free while simultaneously playing the result, which is a very creative experience.

As if this wasn't enough, a number of mathematical transformation algorithms may also be applied, including normalisation, DC offset, phase inversion/offset, reverse, 'Fractalise', filter and FM. A second waveform can be mixed in, with variable balance, phase invert/offset and frequency ratio. 'Fractalise' is worthy of special note; it allows a gradual brightening of waveform material by applying harmonically‑related repetition within the waveform (anyone who has seen a fractal‑generated picture will have an inkling of what is going on here). Whether you understand the theory or not is largely irrelevant, since experimentation is the key and it is hard to come up with genuinely useless material. On the downside, Absynth's sole level of Undo could be restrictive in the heat of experimentation.

Waveform editing in Spectrum mode is a somewhat simpler affair, allowing drawing of single or multiple harmonics with the mouse. Both the amplitude and phase of each harmonic are available for click‑and‑drag editing. Transformation tools include the ability to invert the phase of the harmonics, or apply an overall harmonic shift.

The Envelope Editor

The Controller assignment window.The Controller assignment window.

Absynth features 68‑point multi‑stage envelope generators. Each breakpoint has a set of three parameters — time, amplitude and slope. Time and amplitude may be edited by their parameter boxes, or more simply by simply dragging breakpoints left, right, up, or down in the envelope editing window. 'Slope' determines the rate of change from the previous breakpoint to this one by a steeper, or shallower curve. The window is a joy to use, allowing the simultaneous viewing of multiple envelopes one above the other in lanes; it's not dissimilar to editing controller events in a sequencer. In fact, the similarity to a sequencer is not merely cosmetic, since it allows multiple rhythmic envelopes to be created with reference to one another on the lanes. This provides access to some of Absynth's most exciting features. Full marks to the programmers for the interface — when editing on hardware synths with multi‑point envelopes, my patience has usually worn out by the time I've reached the fourth breakpoint! I tried dropping a few Absynth‑generated loops into Recycle and from there into Reason's loop player, and the results were inspirational. Many of the factory presets also show off these capabilities, with whole rhythm loops and burbling sequences emanating from a single key‑press. Envelope modulation may be applied to each oscillator's amplitude, pitch, and ring modulation, and also to the master filter frequency.

The envelope editing window can be turned into a grid for accurate placement of breakpoints, and events will 'snap' to the grid if you hold down the Control key when dragging. The lock/slide option determines whether the timing of breakpoints after the one being moved will be shifted or remain at absolute positions, and you can designate any breakpoint the sustain/release point.

There are four different envelope modes, which determine how note triggering will be handled. 'Sustain' mode is closest to the behaviour of a conventional ADSR; the release phase is initiated as soon as a key is released. 'Release' mode differs only in not having a sustain phase. 'Loop' mode repeats a specified loop within the envelope, crossing one or more breakpoints, until a key is released. Finally, 'Retrigger' mode forces the envelope to be retriggered at a user‑defined tempo.

LFOs & MIDI Control

LFOs can be edited from this window. As with the main oscillator waveforms, you have a choice of preset and eight user waveforms.LFOs can be edited from this window. As with the main oscillator waveforms, you have a choice of preset and eight user waveforms.

Three LFOs are available, each capable of modulating several parameters simultaneously. As with the oscillators, a choice of waveforms is offered from factory presets, or up to eight user waves, which may be created in the Wave editor. Rate, phase and depth are adjustable, and the LFO will optionally retrigger on receipt of a non‑zero value from a user‑selectable MIDI controller number. LFO destinations include oscillator pitch, amplitude, FM index/balance, filter frequency, effect time and effect pan. LFO depth, rate and sample‑and‑hold rate can be controlled by MIDI controller messages.

Absynth features a sophisticated set of MIDI controller options. Separately selectable continuous controllers are set to modulate FM index/balance (individually for each oscillator), filter frequency (for each filter), effect time, pan and volume. Velocity is assignable to amplitude, FM index/balance for each oscillator, and frequency for each filter. Note scaling can be applied to oscillator amplitude, FM index/balance and filter frequency, and a note scaling curve editor screen allows the precise drawing of complex scaling curves.


Absynth offers three effects. This is the Multicomb delay window.Absynth offers three effects. This is the Multicomb delay window.

Three effects are currently provided; 'Multicomb', 'Pipe' and 'Multitap'. 'Multicomb' features up to six independent delay lines, each one offering delays from a single sample to 740 milliseconds in length with feedback, low‑pass filter and pan. Delay times can be modulated by LFO or MIDI controllers.

'Pipe' implements a simple pipe‑modelling algorithm, simulating a resonating driver at one end of the pipe and stereo outputs somewhere along the pipe's length. Pipe length and output positions may be modulated by LFO or MIDI controller messages, and helpful graphics ensure that the positions of inputs and outputs are clear.

Lastly, 'Multitap' consists of a single delay line with up to 10 seconds delay and three tap points. The first tap has variable feedback control. Delay time on each tap may be modulated by LFO or controller messages.


I did notice one or two rough edges as I worked with Absynth. I had trouble trying to select the waveshaper module as an envelope modulation destination — when you select the envelope destinations, the waveshaper is in the list, but it's always greyed out. The Master filter has to be in a specific mode, or it is also greyed out, but the waveshaper responded to nothing I could find. During editing, I also came across one aspect of Absynth's operation that annoyed me. I went to the on‑screen keyboard to set a note droning in the expectation that I could begin editing. As soon as I tried to switch modules in the patch window in or out, however, the droning note would be cut off. Although this is, perhaps, understandable, it is a shame. Moving parameter values, fortunately, did not cause the same problem.

I'd also have to say that I didn't find Absynth's HR Giger‑esque user interface either aesthetically appealing, or graphically intuitive. A glance at the patch window, for instance, gives little instant feedback to the parameter values within the patch. Sorry, guys — cute, swirly boxes around squared‑off numeric parameter value fields do not a sexy interface make! Rather than meters, knobs, dials and sliders, the designers seem to have contented themselves with numeric data input, and this felt like too much of a backward step to me, although it does mean that parameters can be set to three decimal places. To ease input of such values, each parameter is given coarse and fine editing buttons (and extra‑fine in some instances).

Nor was I particularly comfortable with Absynth Engine firing up in the background when I used Absynth as a plug‑in — it seemed 'untidy', particularly as it meant that I couldn't use standard host‑controlled load or save functions. It gave me the nagging impression of a capable stand‑alone synth that had been brought to market with something of an underdeveloped plug‑in implementation. Maybe that's unfair, but putting Absynth up against an older VST instrument, such as Pro 52, I had to wonder why it wasn't that simple.

Finally, I found the manual a bit confusing, feeling that it failed to guide the user in any logical manner. The description of the menus, for instance, wades straight in without even considering whether you are running Absynth as a stand‑alone application or as a plug‑in. Maybe this would be obvious to an experienced user, but I think a newcomer would find the information here scrappy and hard to follow. This is not typical of Native Instruments, and I'd urge them to take another look at their documentation.


This product represents a genuine alternative in a now‑crowded world of software synths, where emulation of old synthesis values seems to have had something of a stranglehold. The quirkiness of Absynth's wave‑shaping and pipe modelling effects demonstrate that someone has thought about delivering a new slant on an old theme, and I find that laudable. The sounds that can be coaxed from Absynth are worth the effort of getting to know it, but it does require a little thought to get the best out of it, and this means that it will not appeal to everyone. If you are usually content to call up factory patches, I don't doubt a whole batch of Absynth presets will be available on the web, but with this synth, taking that approach would be a bit like buying a Ferrari and hiring someone to drive it for you.

Absynth can generate the weird, wild and wonderful, or it can be tamed into sounding like a more conventional me‑too software synth. The sound quality is extremely good, and many of the evolving, shifting sounds are reminiscent of PPGs, Wavestations and the like. OK, so I have a few bones to pick, but don't be put off the things that really matter. This is an inspirational tool that will please experimenters. The software appears stable, performs well and features some innovative, powerful sound‑shaping tools that allowed me to explore sonic realms I've never visited before. If such experimentation appeals to you, I can happily recommend it.

Absynth As Audio Recorder

When being used as a stand‑alone application, Absynth features a simple audio recorder. Recording is to RAM, so the maximum available time is limited by the amount of memory you have allocated to Absynth. Both stereo and mono recording is supported, and multiple overdubs are permitted in a traditional sound‑on‑sound style, with the option to balance the level of existing audio against that of new material. The results can be saved as AIFF files. None of this is earth‑shattering in concept, but it does offer a useful method of sample creation whilst keeping the creative juices flowing.

Taking The Strain?

Absynth's Processor requirements seemed reasonably modest. Running four plug‑in instances with complex loops did make the audio stutter from time to time, and adding a fifth plug‑in caused more severe choking. It must be remembered that this was all happening on a minimum‑specification processor, and at no time did Absynth actually crash.

Test Spec

Native Instruments Absynth v1.2.3.

  • 300MHz Mac G3 with 512Mb of RAM running Mac OS 9.1.
  • Steinberg Cubase v5.
  • Emagic Logic v4.7.3.


  • Unique sounds.
  • Powerful wave‑drawing and unusual sound‑shaping capabilities.
  • Extremely flexible envelopes with inspired envelope editing window.
  • Stand‑alone 'sound‑on‑sound' record facility for loop creation.


  • Plug‑in implementation not as slick as on other NI offerings.
  • Might hold less appeal for those who just want 'wash‑and‑go' sounds.
  • Absynth's user interface features a considerable amount of numeric parameter data, rather than more intuitive knobs and sliders.
  • The manual could be improved.


Absynth is likely to prove more appealing to the experimentally minded than those of you looking for a quick source of 'bread‑and‑butter' sounds. Some of its sound‑sculpting tools are inspirational, but producing results requires patience. Nevertheless, it can go far beyond what more conventional software synths can achieve. If you like to go beyond using presets and get programming, it's recommended.