VocalsMixing

Vocal Harmony That Stays In Key

Most harmonizer plugins move the pitch by a fixed interval, which is why the third goes wrong on half the chords. Scale locked harmony does not.

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By Nolvra

A Fixed Third Is Wrong Half The Time

The most common complaint about harmony plugins is short and accurate: they just change the pitch by a fixed amount. Ask for a third above and you get four semitones above, on every note, for the whole song. In a major scale a third is four semitones on some degrees and three on others, so a fixed shift is right where it happens to fit and wrong everywhere else, and the wrong ones do not read as harmony. They read as a mistake on the same word every chorus. Everything below follows from that one interval being variable.

What In Key Means For A Harmony Voice

Staying in key means the plugin decides a note rather than an offset. The decision needs two things: a set of notes the song is using, and a rule that every generated voice is snapped into that set before you hear it. Producers usually call that rule a scale gate. A gate applied to the lead alone is only half the job, because the harmony voices are separate decisions and a stack of three can drift out of the scale while the lead sits perfectly inside it.

Three Ways A Plugin Picks The Harmony Note

  • Fixed interval is the fastest to set and needs no key information at all, which is exactly why it fails: the interval it was given only fits some of the degrees you sing over.
  • MIDI guided harmony is exact and never wrong, because you played the notes yourself, but you have to write the part and rewrite it whenever the chords underneath it change.
  • Scale locked harmony asks for a root and a scale, then quantises every generated voice into that set, so the third is four semitones on one degree and three on the next without you touching it.
  • Chord following is scale locking with better evidence: the plugin listens to the track on a sidechain and snaps to the notes of the chord that is actually playing rather than the wider scale.
  • The three are not rivals, they are a priority order, and a plugin worth using tells you which one it is currently obeying instead of leaving you to guess.
  • A voice generated from a pitch you never sang still needs a source: PRISM PRO works from the pitch it hears rather than from a part you enter.

Setting A Stack That Holds

Get The Key Right Before Anything Else

Every method above is only as good as the key you feed it, and a wrong root makes scale locking confidently wrong instead of randomly wrong. If the song came from a loop or a sample you did not make, work the key out first and set it explicitly rather than trusting the first guess.

Give The Plugin The Best Evidence You Have

A chord track on a sidechain beats a scale, and a scale beats nothing. With a chord locked, a generated line lands on a chord tone 95.5 percent of the time, against 36.3 percent for a fixed note. If the plugin cannot name a key from what it has heard, the correct behaviour is to say so and quantise nothing, because a wrong lock is worse than no lock.

Start With One Voice Under The Lead

A third below thickens without competing for the melody. Two voices already read as an arrangement choice, three read as a section. In PRISM PRO the three voices are a third down, a third up and an octave down, each on its own switch behind a HARMONY master switch, and a fresh instance opens with the harmony off, so the first voice you switch on is a choice you make rather than one you inherit.

Set The Balance Before The Reverb

Harmony that sits level with the lead turns the phrase into a chord and takes the words with it. Push the lead in front first, then place the stack, then send both to the same space so they read as one performance. Where that sits in the chain matters as much as the interval does.

What The Gate Is Worth In Numbers

Scale locking is easy to claim and easy to measure, so here is the measurement. With key and scale set, out of scale decisions in the engine go from 12.1 percent to zero. Across all three harmony voices, out of scale notes measure zero as well, because the voices pass the same gate as the lead rather than a looser one of their own. The lead stays 8 to 17 dB in front of the stack, which is the difference between harmony that supports a line and harmony that argues with it.

That is the half of PRISM PRO people notice second. The first half is the talkbox itself, and both halves share one decision layer, so the note the lead commits to and the notes the harmony commits to come from the same source, in the same order, in the same key. If you want to hear it against your own vocals, the trial runs seven days and takes no card. It opens the plugins, and the sample packs stay closed while it runs.

Harmony That Cannot Fall Out Of The Song

PRISM PRO runs up to three harmony voices through the same scale gate as the lead, so the stack lands in your key. Seven day trial, no card, plugins only.

See PRISM PRO

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