A theory engine proposed chords without playing a note

The tool moment

Scaler arrived in 2018 as a MIDI-effect plugin built around music theory rather than sampled performance. Its retailer's own product page, live by 15 March 2018, describes it as “a unique and inspirational MIDI effect that makes finding chords and progressions intuitive and fun,” built around “note detection, scale selection and chord suggestions.” Rather than generating a performance from a sampled instrument, Scaler analyzed a played or MIDI-detected key and scale and proposed chords and voicings a songwriter could audition and drag directly into a session.

What the documents show

The 2018 page states Scaler “can determine what key and scale you're in and suggest chords that match your music, or it can inspire a tune from scratch by providing a set of initial chords in an unexplored key,” drawing on “1,728 scales and modes including genre and artist presets.” Once a scale is set, the page states, Scaler “lays out basic diatonic chords for you to audition” with “dozens of chord variations and voicings to try out,” and lets a user “drag chords and progressions from anywhere in the plugin out to your DAW.” This is the retailer's own product description, written to sell the plugin, not an independent test of how accurately its scale detection performs against a real, noisy MIDI input. The developer has since released further versions; the current developer site shows the product at “Scaler 3,” a later generation than the one this page describes.

What stays with the musician

Scaler proposes chords that fit a detected or chosen scale; it does not decide which of those chords, or which unexpected chord outside the suggested set, actually serves the song, and the vendor's own copy does not claim its suggestions fit every genre without a human editing decision. A songwriter still auditions the harmonic function of each voicing, chooses how far to deviate from the diatonic suggestions for effect, and edits the dragged-in MIDI once it sits inside the arrangement alongside other parts.

Judge it by listening

The product page describes what Scaler proposes, not how any resulting progression will sound in context. A reader can listen for whether a Scaler-suggested progression still serves the song's mood once it sits under a vocal or lead line, and check whether relying on the diatonic chord list produces a progression indistinguishable from other tracks built the same way. This is an editorial listening check, not a method the vendor documents.

• Does the detected key and scale actually match the intended harmony, or just the notes played so far?
• Would the song benefit from a chord outside Scaler's suggested diatonic set?
• Once dragged into the DAW, does the suggested voicing still fit the rest of the arrangement?

Scaler's pitch was theory as a shortcut rather than a shortcut around theory: a songwriter still decides what a proposed chord is for, even when the plugin does the work of finding chords that will not clash.