Fee, Fi, Fo, FM: Explore the World of FM Synthesis
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Four Top FM Softsynths

The four software instruments described below all specialize in FM synthesis, but while they're popular, convenient, and good-sounding, they're not the only options. For example, the Alesis Fusion keyboard includes a full implementation of six-operator FM, and Yamaha offers an FM plug-in board (the PLG150-DX) for their Motif keyboards.

Ableton Operator ($149)

Operator is a basic four-operator, one-filter synth. It's available as an optional add-on for Ableton's popular Live music production software, and can be used only in Live, not in other hosts. Operator has other significant limitations, as well. Its ability to respond to real-time controllers arriving via MIDI is less than adequate, and it's the only synth in our roundup that provides fixed algorithms rather than letting you roll your own. Its envelopes can do loop playback, but they're ADSRs (attack-decay-sustain-release), and can't be programmed with extra segments.

The main advantages of Operator are that it has an excellent library of presets (many of them programmed by my colleague Francis Preve) and that it integrates well with Live. Live's handy device group feature, in which a plugin instrument is linked with plugin effects in a preset that can be recalled with a single click, works only with Ableton's own instruments, not with third-party software.

Figure 3. Ableton Operator has four operators (on the left), graphically editable ADSR envelopes (center), and a multimode filter (center right). The four colored boxes in the bottom gray rectangle on the right show the currently selected algorithm; modulators are in the top row, and the carrier is in the bottom row.

Image-Line Sytrus ($179)

It's a close call, because Octopus is excellent as well, but on balance, I feel Sytrus is the best instrument in this roundup. Unfortunately, it's not available for the Mac OS. Sytrus has six operators, three multimode filters, and effects (three highly programmable waveshapers, a rich multi-voice chorus, a full-featured reverb, EQ, and three delay lines). You can define up to 128 overtones in the waveform editor, which also includes parameters for things like tension and skew. Plucked-string synthesis is part of the package, as are ring modulation (RM) and a two-dimensional mousable control surface.

One of Sytrus's strengths is its generous complement of envelopes and LFOs (more than 50 of each). You can copy and paste envelopes, and the program includes numerous templates to aid programming. Sytrus's arpeggiator is versatile, though it's implemented in a way that makes it less than intuitive to program: the break points of looping envelopes can be defined as arpeggiator steps.

Figure 4. Image-Line Sytrus has dozens of envelopes and LFOs. After selecting an operator (top row), you choose the aspect of its operation that you want to control (PAN, VOL, MOD, etc.; second row) and then edit the envelope, LFO, keyboard scaling curve, velocity scaling, response to the two-dimensional X/Y controller, and so on. The matrix at the right routes signals from one operator to another, or to and from the filters.