discoDSP – OPL v3.2.0 for WiN

discoDSP OPL emulates Yamaha OPL chips, the FM synthesizer used in AdLib and Sound Blaster soundtracks in the late 80s and 90s. A classic two-operator FM synthesizer with all eight OPL3 waves and percussion mode, expanded to multi-operator patches based on eight YMF262 chips. 16x oversampling, over 11,000 instruments, SBI, WOPL, and TX81Z import.

Based on the YMF262 (OPL3). Classic patches use dual-operator channels, like those found in AdLib and Sound Blaster games, while multi-operator patches use dual-operator channel pairs. The eight-chip set (144 channels) allows for larger patches and unison chords.

Each operator has its own waveform, frequency multiplier, ADSR envelope, decay, key scaling, and velocity response. Eight waveforms for each operator: sine, half sine, absolute sine, quarter sine, alternating sine, camel sine, square, and logarithmic sawtooth. It’s the combination of waveforms that makes the OPL what it is, because sine alone isn’t enough.

Multi-operator mode allows for up to four modulators and four carriers per note. Choose from eight algorithms (FM, Additive, 3-Stack, 4-Stack, Two-Pair, Stack + Sine, 1-3, Three-Pair) or create your own using the Yamaha-style algorithm diagram: drag a modulator to connect it to others, click a wire to remove it, and click an operator to edit it. Each patch is compiled into chip channels with 2 and 4 operators. Multi-operator instruments are saved in the .sbix format, which other instruments still recognize as standard SBI.

The suite includes over 11,000 instruments: an SBI library sorted by category, 4-op and OPL3 banks created for computer games, General MIDI sets from classic game soundtracks, and Yamaha TX81Z voices. WOPL and WOPLX banks (OPL3 Bank Editor, libADLMIDI), OPLI instruments, and TX81Z, DX21, DX27, and DX100 sysex dumps are loaded without conversion, and levels are normalized so that 4-op patches correspond to 2-op ones. SBI presets (Creative Labs’ instrument format for Sound Blaster cards) are loaded via drag and drop.

Drums mode adds bass drum, snare drum, tom-tom, cymbal, and hi-hat, each assigned to specific operator slots and waveforms.

In AN1x-style unison, each note is layered with five detuned layers with a 32-step detune depth and stereo spacing, while pitch panning distributes notes across the stereo field based on pitch. The output features a master volume control from -48 to +12 dB and a Valve or Tape saturator that processes only peaks. MPE, sustain pedal, and sample-accurate MIDI are supported.

The emulation runs on a rewritten engine with our own developments. The chip itself is oversampled 16x, eliminating aliasing that occurs with FM synthesis at high modulation settings, while pitch, envelope sync, and key scaling are adjusted so that patches sound consistent across all settings. Offline reverb uses a linear-phase filter with the specified delay, ensuring rendering matches what you’ve heard. Inactive chips and channels are skipped, so CPU load depends on the audio being played.