VOPM VST GUI in FSThost VOPM in Carla Algorithm 0 Algorithm 1 Algorithm 2 Algorithm 3 Algorithm 4 Algorithm 5 Algorithm 6 Algorithm 7



VOPM is a Virtual OPM FM-style polyphonic synthesizer developed by Sam, and ported to linux by the Jucetice Team at An emulation of Yamaha's YM2151 OPM sound chip, VOPM has four operators (oscillators), and is ideal not only for chiptune-style music, but also for more complex sounds as well.

The first screenshot of VOPM above is the Windows VST version running in linux with Wine and FstHost, which allows the original GUI layout and permits .fps file saving and loading. The second screenshot is VOPM ported and loaded in the Carla host.

VOPM provides eight algorithms (click small screenshots above to view) for arranging the four operators, nominated C1, C2, M1 and M2. These can function as either carriers or modulators. M1 is also capable of self-modulation, and C2 can be used to produce pitched noise output.

All parameters in the original GUI can be displayed as Decimal values or Hex values (selector located under the preset import/export buttons), but the ported linux version displays in Hex mode only. TL is the maximum amplitude level, and AR indicates the Attack Rate (highest value is fastest rate). DL1 is the first decay level, and DR1 is the first decay rate. DR2 indicates the rate at which the sustained note should then return to zero. RR is the final release rate when the note is released. (The envelope shapes, shown in the original VST GUI, are not provided in the ported linux version.) MUL is the related operator's frequency multiplier. DT1 is fine detuning, and DT2 is coarse detuning. KS is the key follow parameter.

On the left side of the GUI, any operator can be omitted by clicking the respective OP-MSK button. If the noise button is clicked, C2 will produce noise rather than a sinewave. The NFRQ slider controls the noise signal frequency. The FL slider controls the feedback loop of M1 when in self-modulating mode. AMS and PMS control the depth of the amplitude and pitch modulation; the actual amount is set using the AMD and PMD sliders. The rate of the LFO for these is just to the right, labeled "FRQ."

NB: If you experience low audio levels, check to see that the TL value(s) of all sounding operators are set to *minimum* values.


A few patches of my own, in .fps format (for use with FstHost) : VOPMPatches01

A collection of rolling presets, (mine and others available online), converted to Carla's .carxs format: VOPM-CarlaPresets --Updated June 08, 2018.

Some patches and an unofficial programming manual are available at One-Synth-Challenge (OSC) HERE


VOPM source code at
VOPM source code at