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Mac Audio Column

Absynth v1.0
- Not just another software synthesizer -

by Armand ten Dam

Software synths are hip. Instead of spending a lot of money on another set of keys and knobs that you don't really need softsynths offer new sounds and new opportunities usually for a fraction of the cost of a traditional hardware synth. A CDROM player (or in this case just a modem) and some storage space on a harddisk is all that is required. General computers provide the computational power and PCI-audio cards provide the high quality D/A conversion.

To date much of the focus has been on recreating the past on a monitor screen. We see classical VCO-VCF-VCA configurations, knob-equipped synths operated by mouse clicks and drags in retro-designs. Absynth takes on a different approach. While we see well-known oscillator, filter and effects blocks from the outside; it is inside these modules that a whole new sonic world emerges. To give you a head start: think of something like Native Instruments' Reaktor meets MiniMoog halfway. When you first open Absynth the accessibility is obvious. No need to start reading the manual first. You will find familiar concepts like oscillators, lfo's and filters. When you listen to the preset bank though, you will notice that there is a lot more going on under the hood than is eminent at first. There is no need however to build your own algorithms or construct synthesizer modules from scratch. Sonically Absynth takes off where other software synthesizers have stopped. Just browse through the presets and be surprised. Absynth is capable of producing highly innovative sounds. With a large number of the sounds Absynth produces you may think: "How in the world did they put this together?" Although it is not, you might ask yourself whether Absynth is built around a sample playback engine. The sonic variety of Absynth is original and expansive. How is this all put together then?

Under the hood

The oscillator module is the soundgenerator in Absynth. An oscillator is the starting point of each of three sound generating channels in Absynth (in fact each is a complete synthesizer on its own). It operates in one of four modes single, double, FM or ringmodulation. In single mode the oscillator generates a single cycle waveform. Double mode gives you two oscillators (main and mod) in one block and thus a maximum total of six oscillators in a single patch. The main and mod oscillator each have their own waveform, pitch tracking, tuning and phase. In FM and ringmodulation modes the mod-oscillator is used for modulation of the main oscillator. A generous selection of built-in waveforms is available but Absynth also lets you create your own. You can either draw a waveform or build one from individual harmonics. For each of 64 harmonics you determine its amplitude and phase. From this Absynth calculates the resultant waveform. Technically speaking this offers you additive synthesis. Be aware however that since Absynth generates a single static waveform only, it is not as powerful as dedicated additive synthesizers like the Kawai K5 and K5000 series nor the Kurzweil 150 where individual harmonics have their amplitude modulated over time by an envelope generator.

Next in line are the filter blocks. Absynth's filters are multimode filters. They offer HPF and LPF filters at various slopes as well as band pass and notch filters. There are operating frequency, resonance controls and bandwidth and Q-parameters when applicable to the filter mode. Having passed through the filters the signal can be modulated in the mod-block. Currently this offers a ringmodulator only. It is very comparable to the ringmodulator in the oscillator block. This time however it operates on the filtered signal of that generated by the main and mod oscillators together. An Absynth patch consists of three of these oscillator filter mod lines. Absynth is in a league of its own when it comes to envelope generators. They are a far cry from the traditional four stage modulator (ADSR) that we once used to know. In Absynth you define up to 68 breakpoints per envelope. Envelopes are assigned to the amplitude of the oscillators, filter frequency or oscillator pitch. The envelopes cannot be synced to midi-tempo information but are scalable relative to BPM and beat divisions. This means that it easy to create (poly-) rhythmic structures tuned to a specific number of BPM by just applying the envelopes to oscillator volume. Each of the breakpoints operates in one of four modes: sustain, release, retrigger and loop. In fact the envelopes offer so many possibilities that when you start delving into the EG-module it may seem a bit daunting at first. Take a closer look at some of the pre-set patches that make you think that there is an arpeggiator on board (there isn't!). These offer a good starting point to learn more about the rhythmic possibilities of the envelopes. Built-in aides help you along the envelope path are copy/paste operations, gridlines and markers.

Other modulators in Absynth include three lfo's per patch and selectable midi-controllers. The lfo's have the same range of waveforms available for modulation as the oscillators use for sound generation. This includes your own carefully crafted waves. The lfo's are assignable to oscillator amplitude, pitch and balance, filter frequency, effect time and panning. Midi controllers operate on a similar set but also include the lfo's parameters as destinations. The one built-in limitation here is that the possible modulation destinations are hard-wired. I think that Absynth could do with user selectable modulation sources and destinations from a larger amount of synthesizer parameters for more flexible modulation routings.

absynth patch editor
Figure 1: Absynth patch editor

The three oscillator-filter-mod channels are fed into a waveshaper module, then filter and effect module. The waveshape module distorts the input signal by a waveform. The effect of this non-linear distortion ranges from a subtle warming (a la tube amplifiers) to a roughly ripped and clipped signal. Apply with care but do definitely try this at home. Both the waveshape and the filter module have the option to mix the three oscillator channels before doing their work or process each channel separately. The effect section is rather more creative than the often seen mix 'n match of reverbs, choruses and delays. The three delay based effect types are multicomb, multitap and pipe. The multicomb has six short delay lines that create resonator-type effects. The multitap delay runs the signal through three delays with a maximum delay time of ten seconds. The pipe is based on the physical model of running the signal through a pipe where the input position of the signal and the two output positions of the signal as well as the length of the pipe are being modulated by a midi-controller or lfo.

With its oscillator modes and waveforms Absynth has a rich palette of sonic material to start working from. The elaborate envelope mechanism offers the tools to mould the material either rhythmically or evolvingly by applying many independent envelopes to various parameters. The waveshape and effect modules spice up the final dish. Think rich, digital, groovy and atmospheric. Installation and documentation

Absynth comes in an electronic downloadable (about 3 Mb) version only. The archive unpacks into a folder that contains the actual synth-application, a bank of factory presets and documentation. The documentation is based on a program called eDoc. This converts documents into electronic pages with a clickable index. You don't need to worry about eDoc; its engine is incorporated in the documentation. I guess pdf documentation would have made it even more accessible and portable, but that is just a minor quibble. There is a reference manual, quick start and readme files that should get you going easily.

Absynth requires any PowerMac that runs at 100MHz or faster, at least MacOs 8 and 16 MB RAM or more. I tested Absynth on a PowerMac 8600 upgraded with an XLR8 G3/450 card, running MacOS 8.6 and plenty of RAM. To get Absynth running is as simple as unstuffing the archive and double clicking the application. For sound output it uses Apple's Sound Manager. If you have an audio-card installed that comes with a Sound Manager driver you can use that of course and take advantage of the higher quality D/A conversion. In my setup I have a MOTU 2408 and it worked flawlessly with Absynth. The little CPU performance indicator in Absynth averaged somewhere between and 10 and 30 percent. Never was CPU performance a problem. Carefully setting the audio-buffer size meant that latency was hardly noticeable. Midi operation requires that you have OMS installed. OMS does not come with the package so you will have to get that from elsewhere ( All in all if you have OMS and a midi-keyboard already in place things couldn't be easier with Absynth open the application and start playing. If for some reason you don't have access to OMS you can always play Absynth via the on-screen keyboard. This allows you to control the patch with midi-controllers, pitch bend, aftertouch and velocity.

User Interface

The Patch Edit window contains the basic modules (oscillator filter mod- waveshaper) that make up an Absynth Patch. These modules are incorporated in the signal path by switching them on. This requires a single mouse-click and the module will light up nicely. A separate Navigator window gives you access to editing windows for waveforms, envelopes, lfo's, midi-controller assignments and the effect section. Editing parameters is done numerically by click-dragging the mouse up or down. While some people prefer to turn on-screen-virtual knobs, I quite like the method that Absynth offers. Editing values is implemented separately for all digits of parameter values. This allows you to set coarse values first before fine tuning a patch. The one thing that I would like to see differently is in the organization of the modulation paths. They are now hidden in three different modules: the envelope module, the lfo module and the controller window. It is not easy to get an overview of the modulators of a certain parameter. Keeping a lot of windows open is the solution I guess.

It even gets better...

Rhizomatic software gives you the opportunity to try Absynth before you buy. The demo-version of Absynth is available as a free download at their website ( The demo version differs from the full version in the following ways:

    [1] the only presets bank you can load is the factory presets bank

    [2] saving edited or your own patches is disabled.

Note though that you can explore all of Absynth's sonic capabilities and that you can even capture performances as audio files (stereo AIFF) and use these creations as samples in an audio sequencer. You owe it to yourself to go, get and play with it. The price of US$150 is very reasonable for this capable synthesizer. In the time I have worked with the demo version and during the writing of this review the technical support provided by Rhizomatic was always very prompt and helpful.


With a version 1.0 there is bound to be a wishlist. On mine are import and export of user created waveforms and those available in generic formats like AIFF and WAV, fine tuning some user interface issues, synchronization to midi-tempo and maybe a wider range of freely selectable parameters as modulation destinations. Also Absynth's audio output can be routed through Sound Manager only. Support for ASIO devices (pretty much a standard to drive third party audio hardware these days) would be welcome. Note that the stability of Absynth is excellent as of now. The program hasn't crashed on me once.


Absynth is nothing short of an excellent debut in the software synthesizer market. It comes with decent documentation and is very reliable. Most important though is that is very easy to operate and gets high marks for originality and sound quality. I conclude with some straightforward advice: download and play!
Armand ten Dam

[For info on Audio Apps support for the G4's velocity engine (and in some cases dual processor support), see the Audio section of the FAQ-Mike]

Note: Thad Brown's been busy with other things and I'm glad this column has gotten him some much deserved recognition in the audio world. (See below for links to Thad's 60 issues of the Audio column here). I welcome any reader submissions on the subject of Mac audio. If you have an article or commentary to submit, please contact me. Thanks!-Mike

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