Software mastering has never been short of Swiss army knives. What’s missing are tools built around how you actually work, by eye and by ear, without hopping between windows. That’s exactly the pitch of REISEI, the debut plug-in from ONRI Audio, made by a designer and mastering engineer based in Japan who first built it for his own sessions.
Everything on one screen
REISEI arranges six processing sections — compressor, saturator, EQ, dynamic EQ, stereo imaging and limiter — around a single analyser. Each module has its own on/off switch, and crucially the chain reorders freely: nothing forces you to saturate before you EQ, or to compress last. But the real design move is elsewhere: the analyser isn’t a readout, it’s the control surface. Every band, node and grip is manipulated directly on the spectrum. You don’t dial numbers while glancing at a curve nearby; you act on the curve itself.
One telling detail betrays genuine mastering culture: the UNITY control auto-compensates output level against input, so your before/after comparisons happen at matched loudness. That’s the basis of an honest judgement, and it’s too often skipped.
PARTIAL mode: an EQ that follows the note
What sets REISEI apart is its PARTIAL EQ mode, built on additive resynthesis. A conventional EQ works on a frequency band: dig “around 3 kHz” and everything passing through is affected, whatever note is playing. PARTIAL does something else. It locks onto a specific harmonic in the signal and follows it as pitch moves. Target the 5th harmonic of a vocal, a horn or a bass, and REISEI keeps it in its sights even as the melody shifts.
On that isolated harmonic you can then lift it, cut it, or flip it into anti-phase to cancel it outright. The process is described as strictly linear: by design it adds no distortion. This is a scalpel — the kind of thing that fixes a resonance “ringing” on one particular chord without touching the rest, where a classic dynamic EQ would still work by band, more bluntly.
The catch: macOS Apple Silicon, and nothing else
REISEI comes in VST3 and AU. It does, however, require macOS 14.0 or later and an Apple Silicon chip (M1 and up): no Intel build, no Windows. The launch licence is $299 until August 31st ($399 after), covers three machines and includes updates within the current version line; a full 14-day trial is on offer.
That hardware bar isn’t trivial. It shuts out a sizeable slice of studios still on Windows or Intel Macs — a deliberate bet on squeezing Apple’s silicon, but one that narrows the audience.
A tool for people who really master
REISEI belongs to a line of tools “for people who master by eye and ear”, set against the flood of dynamic EQs and resynthesis processors. It slots naturally into a well-stocked mastering chain: the Dangerous Music BAX EQ for broad strokes, the Softube Reference EQs for colour, and a firm grasp of digital gain staging and compression so you don’t turn this scalpel into a chainsaw.
Harmonic tracking with anti-phase cancellation is the kind of feature that, used well, solves in ten seconds a problem you might otherwise chase for an hour. Used badly, it sterilises a mix by smoothing out everything that vibrates. As ever in mastering, the tool doesn’t replace the ear, it arms it. We’ll see how PARTIAL holds up on dense, real-world material; on paper it’s one of the most interesting EQ ideas of the year. The product page is over at ONRI Audio.
