Originally Published: Monday, 2 October 2000 Author: Alex Young
Published to: enhance_articles_multimedia/Audio Articles Page: 1/1 - [Printable]

Software-Based Synthesizers for Linux

Alex takes you on another romp through Linux as a multimedia tool, and introduces you to the super-cool and ultra-addictive world of soft synthsizers. Whether you're a Devo fan or you rave to the strains of Orbital, this one's for you!

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To most people's surprise, electronic instruments have been around since early pioneering work in the 1880s. Hermann Ludwig Ferdinand von Helmholtz (1821-1894), a German physicist and mathematician, built an electronically controlled instrument using electromagnetically vibrating metal tines and glass resonating spheres to create relatively complex sounds [1]. Electronic instruments, however, became more useful with the advent of vacuum tube technology in the 1960s and then later with integrated circuits. Now most of us have powerful enough home computers to emulate these instruments - creating virtual machines that can simulate complex waveforms and produce new timbre for compositions.

The first software-based synthesizer (softsynth) I tested was ARTS (Analog RealTime Synthesizer). This application is very different than what I expected, and somewhat reminiscent of Buzz. The basic concept behind ARTS is that complicated audio constructs can be built up from very simple modules. Each module is an entity which can be connected to other modules, forming a stream of sound and "position" signals which flow through each processor. I found the concept analogous to creating a flow diagram (or even an entity relationship diagram), then executing the diagram and observing the output. The finished collection of connected modules is dubbed (in the ARTS jargon) a structure, which can be named for reference and then published to the ARTS server.

The ARTS server is actually a daemon which provides the backbone to ARTS. By using this system, ARTS can dynamically create structures as they are needed. The example in the documentation shows how a midi event could be used to trigger a bass drum structure. This simple example highlights the inherent modular structure that runs throughout ARTS: incredibly complex musical constructs can be built from many small structures (or modules at a more atomic level) interacting.

After initially struggling to setup the package (I didn't have KDE installed, so I used the statically linked binary), I launched the ARTS server and the ARTS builder. The builder allows the user to take the role of a 'sound architect,' assembling the modules as previously described. At first the package was a little tough to get to grips with; indeed, the learning curve is quite steep. However, following the tutorial, which can be found in the online documentation, gave me initial results that spurred on more experimentation.
The Ultramaster Juno 6 is an attempt to simulate the Roland Juno-6 analog synthesizer. This program emulates subtractive synthesis, which is an important concept in synthesizer technology whereby a raw waveform is selected and frequencies are carved away to produce a useful sound. If, for example, you wanted to create a wind instrument, a squarewave is the most appropriate waveform due to its hollow sounding quality. Other important tools to understand when using an analog synth (or in this case, a virtual-analog synth) are LFOs (Low Frequency Oscillators) and VCFs (Voltage Controlled Filters). The LFO is usually used to modulate other signals, and the VCF is used to reduce or emphasise specific harmonics created by the VCOs (Voltage Controlled Oscillator). By using these simple tools (waveform selection, modulation and filtering), one can remove and accentuate certain frequencies and also increase or decrease the rate of modulation, thereby subtractively synthesizing an instrument (or creating a new timbre).

The interface to the Juno 6 is excellent; it is basically a close graphical representation of a real Juno. You can interact via the keyboard, mouse or from a midi instrument. The program creates excellent sounds, which I personally would sample and sequence with a dedicated sequencing package, although you may prefer triggering Juno 6 via midi.

According to Ultramaster.com, the two authors of Juno 6 have quit their jobs to focus on professional Linux audio software development, and their first commercial venture is the RS101 which is available as an RPM or compressed tar file. Although this package costs $65, it is excellent. It combines synthesizers, sample players, effects and a sequencer with an excellent GUI to form a package that I highly recommend. There are also mp3s on the site that show off some of the program's capabilities. It didn't take very long at all to start creating my own loops with effects, and the program seemed as addictive as Rebirth!

SpiralSynth is the next softsynth I tested, featuring three oscillators and envelopes, an LFO, a global envelope, two mixers, delay and routing controls. It can also save your meticulously sculpted sounds and record live output (played via the keyboard). Unfortunately, this program is currently early in development, and while it creates exceptionally high quality sounds, its MIDI support is not yet fully functional - although a basic MIDI interface exists. In addition, it is monophonic, but the author wants polyphony in the near future.

I truly enjoyed playing with SpiralSynth, and after at least an hour of trying to mimic the French band Air, I went on to look at BEAST/BSE (the Bedeviled Audio System and the Bedeviled Sound Engine).

BEAST/BSE is an ambitious project to create an audio system that supports multiple song and sample formats as well as software synthesis. When I tested the application, it was evident that it is still in early development; however, I did manage to create some simple sounds with it. The GUI is lacking in areas, and I found it unresponsive at times, but the project does have exciting goals, so either keep your eye on it or help in development!

The final package I tested is gsynth, a modular synthesizer that uses GTK+. Again, this program is in a very early development, featuring only two modules: a TB303 and Octave. While the TB303 does sound like a simple Roland TB303 emulator, the way the package abstracts the creation of music doesn't seem as conceptually sound as ARTS. However, if the interface is improved slightly, and more modules are added, then the program could be a very useful tool. The sequencer implementation is reminiscent of SoundTracker, so it should be instantly accessible to many trackers out there, but unfortunately as far as software synthesis goes, the package is severely lacking.

If you need a new source for sounds and want the power and reliability of Linux, download and play with some of these programs. Although they have their serious applications, they also provide a little escapism for Orbital (or your favorite electronic musicians) wannabes. However, please note that I cannot be held responsible for their addictive nature!

References: [1] http://www.obsolete.com/120_years/intro.html

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