FM synthesis is such a versatile way to provide a wide timbral palette that many analog-style synths — hardware and software — offer a little FM (frequency modulation) on the side.
Sytrus' Algorithm/Route matrix (grid on right) routes operators.
But genuine FM instruments are more unusual. Image-Line Sytrus, which was originally available only as an option for FL Studio, has now been released as a VSTi/DXi soft synth, making it a worthy competitor for players such as Ableton and Native Instruments.
UNDER THE SKIN
Sytrus' sound engine starts with six-operator FM, programmed in a knob matrix that lets any operator (FM-speak for “oscillator”) modulate any other. Individual knobs in the 9×9 matrix can be muted with a right-click for ease in programming. These knobs can't be automated, but both operator output level and modulation input level can be.
Calling Sytrus an FM synth is a gross oversimplification. Three multimode resonant filters, each with its own waveshaper, can be arranged in series or parallel, and operators can feed filters in any type of mix. Thus, Sytrus can function as three-layered, two-oscillator analog subtractive synths within a single patch, producing warm string pads you'll never hear from a Yamaha DX7.
Each operator's waveform can be custom-designed using a basic additive synthesis interface with amplitude control over each overtone. In addition, any operator can be switched to a Karplus-Strong plucked-string algorithm. Sytrus' envelope generators — more than 50 of them — can be given an unlimited number of segments and can sync to the host clock. Each envelope segment can have its own curvature. The LFOs are just as numerous, as are keyboard and velocity response mappings.
The effects page has a chorus, three delay lines and a reverb. A Unison mode, EQ and a “mouseable” X/Y modulation window deepen the feature set. There's also a comment field for adding notes on individual presets, but this didn't work well in Cubase SX3 because of Cubase's tendency to respond to QWERTY key commands. It worked in other hosts I tried.
INTO THE SQUEEZER
I've used Sytrus 1 quite a bit in FL Studio, and I've found its sounds to be rich and appealing. Although FL Studio can operate as a VSTi or ReWire client, being able to use Sytrus as a VSTi plug-in is more convenient. However, saving and loading programs and banks is more awkward in Sytrus VSTi than in FL Studio for reasons that would be too tedious to explain. Program handling is manageable using the host's save .fxb/ .fxp commands. Sytrus will load original Yamaha DX/TX programs in .syx format. Such files are readily available online, giving Sytrus a vast (though variable-quality) sound library.
Version 2.02 adds MIDI Learn for the externally controllable parameters. Even so, Sytrus is not set up as well as some synths are for real-time expressive control from a keyboard. Few of the factory patches add vibrato in response to the mod wheel, and setting up this routing is awkward. Velocity-to-amplitude response in Sytrus' original version couldn't be shut off, but thanks to the new Unlink Velocity switch, I was able to set up no-velocity organ patches and inverted-velocity crossfades. (This switch is global, unfortunately — a bug reportedly fixed in Version 2.0.6.) There's no velocity control over envelope segment times, and as I actually play the keyboard, I miss this feature.
The arpeggiator is implemented in an eccentric way. Looping envelopes are used, with each envelope breakpoint being given an arpeggiator step value (which can be previous, same or next). How to set up arpeggiating envelopes is poorly documented. The factory patches show that Sytrus can run three simultaneous arpeggios at different tempos or perform a complex octave transposition pattern in response to a simple chord on the keyboard, but it took me awhile to figure out how these effects were programmed. Fortunately, Image-Line provides arpeggiator-type envelope templates. You can also save and load your envelopes.
Despite these problems, I used Sytrus 2 on several projects and was very pleased with the results. After launching Cubase and choosing a beat in Spectrasonics Stylus RMX, I added three instances of Sytrus: one playing a fat synth bass, another a trance lead and a third doing a Eurodance syncopated riff that was built into the patch. The bass wasn't cutting through enough, so I edited the waveshaper curve to add a little more buzz. Then I switched to Ableton Live and used four instances of Sytrus to create a funky riff with bass, clavinet (love that plucked-string algorithm!), arpeggiated pad and lead. There are lots of automatable parameters, as well as fine sound quality and reasonable CPU usage — no complaints here.
SYTRUS ISN'T A LEMON
There's no shortage of fine soft synths on the market, but Sytrus ($179, or free with SL Studio XXL, a $349 download) ranks high on my list, thanks to its extremely versatile voicing options. It's not as easy to program as some synths: Even for FM experts, the user interface takes some getting used to. But it's a great value and deserves to stand out in a crowded field.
Image-Line, 32 92-81-15-33, www.sytrus.com.
Jim Aikin is the author of Power Tools for Synthesizer Programming (Backbeat Books). He hangs out at