Jun Murakami has released a 4-operator FM software synthesizer modeled on the Yamaha TX81Z, a compact 1987 rack unit best known for originating the “Lately Bass” preset that shaped late-80s and 90s dance music.
Synth81Z was built the same way as Murakami’s earlier Synth-80: through exhaustive hardware measurement rather than a generic FM chip emulation.
The TX81Z’s sound is concentrated in a single FM chip, the YM2414 (better known as the OPZ), and its output stage. Being digital synths, Yamaha’s FM chips have been documented and emulated many times before. But once I focused on the TX81Z as a single instrument, it became clear that those implementations fell far short. And so, as with Synth-80, the development of Synth81Z began with exhaustive measurement of the hardware.
In the end, it matches the hardware in detail: the phase resolution of the operators and the rounding of the waveform tables, the fine detail of each of the eight waveforms, output levels that change with the algorithm, the timing of every envelope step, the response to the LFO, velocity and controllers, and the frequency response from the DAC through the output stage. Everything, “Lately Bass” included, was then pushed to the limit by ear against recordings of the real unit.
Synth81Z features
- Up to 32-voice polyphony (8/16/24/32), with 8 matching the original hardware and higher settings standing in for stacked chips.
- 8-part Performance mode with hardware-compatible layers and splits, plus continuous pan and an independent LFO per part.
- 5-slot effects rack with twelve effects inherited from Synth-80: four choruses, delay, phaser, flanger, EQ, compressor, distortion, reverb, and arpeggiator.
- Built-in editor and librarian, mirroring edits to a connected real TX81Z over MIDI, with SysEx send/receive, .syx/.mid import, and a bank builder.
- Single-screen interface showing every operator’s waveform, frequency, output level, envelope, and scaling at once, with click-for-hint parameter explanations in English or Japanese.
- MIDI Learn and DAW automation throughout, with polyphony set back to 8 reproducing the single-chip hardware behavior exactly.
- 360+ factory presets included, plus a free bonus patch set (46 voices/6 performances by Saif Sameer) bundled from version 1.0.0.
Synth81Z for Windows and macOS (VST3, AU, AAX and standalone) is available to purchase for the introductory price of $39 USD until October 31st, 2026 (regular $59 USD).
More information: Jun Murakami App Factory
