Fee, Fi, Fo, FM: Explore the World of FM Synthesis
Pages: 1, 2, 3, 4

LinPlug Octopus ($149)

The prize for most oscillators (eight) goes to Octopus (see Figure 5). This synth also has a sample playback oscillator, whose output can either be listened to or used as an FM modulator, plus two filters and a waveform designer with 32 overtones.

Rather than pair oscillators with envelopes in hardwired operators, Octopus defines its envelopes (up to 32 of them) in a separate part of the panel. A given envelope can be used to control the outputs of many oscillators at once. This makes for an efficient use of DSP resources, but makes Octopus a bit more difficult to program, even than other FM synths. Octopus has no LFOs; instead, looping envelopes are used for LFO-type control.

Also included in the feature set are chorus, delay, reverb, EQ, a pair of step sequencers, and the ability to load microtuning files. (A huge assortment of tunings is included.) In its 1.1 release, Octopus is not entirely free of bugs, but it also has a lot going for it.

Figure 5. LinPlug Octopus packs eight oscillators, each with adjustable feedback. (Click to enlarge.)

Native Instruments FM7 ($339)

The first software-based FM synth, FM7 is closely patterned on the venerable Yamaha DX7 in certain respects, from the controller input implementation to the panel graphics. FM7 is the oldest instrument in this roundup, and set the standard in the field with its multi-segment envelopes and the use of a freely configurable algorithm matrix. Only 32 preset waveforms are provided, and FM7 has one dual-filter module rather than two or three separate filters. A distortion "operator" is included; the only other effect is a delay line.

Like Sytrus, FM7 can load DX7 patches in a system-exclusive file format. Thousands of these patches are readily available online (though the quality of the free downloads is not uniformly good).

You can run FM7 as a standalone softsynth or as a VST effect plugin rather than as a synth. (Whether these capabilities justify the high price is for you to decide.) When it's operating as a plugin, the audio input can either be processed by its distortion and filters or used as a carrier or modulator. That's useful for producing a variety of metallic and distorted effects; the main limitation is that most VST effects can't receive MIDI note messages from the host. An important exception is Mackie Tracktion, which would be an excellent host for FM7 or any other plugin synth that has audio inputs for effect use, because it can route MIDI directly to effects.

Figure 6. The sliders and buttons on Native Instruments FM7 look a lot like those on a first-generation Yamaha DX7. You select operators with the buttons along the top. The graphic area on the right can be switched from the envelope-and-keyboard-tracking display (shown) to the algorithm matrix. (Click to enlarge.)

You Ought to Be on FM

FM synthesis is a complex subject. In this brief article we've only scratched the surface. The good news is, if you'd like to explore FM, you have more good software options than ever before. Today, a good FM synth is capable of both analog subtractive synthesis (similar to old-style Moog and ARP instruments) and a basic form of additive synthesis (building up a complex tone by stacking overtones manually). Thus, it's a worthy choice for almost any musical task, especially when you're looking for an extra helping of expression or sparkle.

More FM Goodness

ThMan's All Free VST Plugins Database has links to scads of FM softsynths, though most are Windows-only.

OPLX features links and information about the OPL FM chips that voice millions of cell phones and Sound Blasters.

Feeling handy? Here are directions for building a hardware FM synth based on OPL chips.

And for analog FM experimentation, there's the Zeroscillator from Cyndustries (at right).

—David Battino

Jim Aikin writes about music technology for a variety of publications and websites. His most recent books are Power Tools for Synthesizer Programming and Chords & Harmony.

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