MVB Tuner

Free pure & just intonation tuner and chord drone

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Tap to add notes · double-tap to set the root · slide the keyboard for more octaves.

Strobe tuner

Bands stand still in tune · drift right = sharp · left = flat

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±0¢
Start the microphone and play a note.

A free pure intonation tuner and drone

MVB Tuner is a browser-based just intonation tuner and chord drone for band, orchestra, choir and jazz musicians. Play any chord on the keyboard or tone wheel and it identifies the chord, marks the root in purple, and tunes every other note to its pure ratio above that root. Flip the Equal / Pure switch to hear exactly how far each note moves.

How to use it

  1. Tap notes on the keyboard (slide it for all 88 keys) or the chromatic tone wheel. The drone starts on its own.
  2. Read the chord name and the cents offset on each note, for example E −13.7¢ in a C major chord.
  3. Double-tap any key to make it the root and move the whole chord there.
  4. Start the microphone and play your note. The strobe tuner bands stand still when you are in tune; in Pure mode they freeze on the just pitch, not the tempered one.

Just intonation cents chart

How far each pure interval sits from equal temperament, measured from the chord root:

IntervalRatioCents vs. equal
Unison1/10
Minor 2nd16/15+11.7
Major 2nd9/8+3.9
Minor 3rd6/5+15.6
Major 3rd5/4−13.7
Perfect 4th4/3−2.0
Tritone45/32−9.8
Perfect 5th3/2+2.0
Minor 6th8/5+13.7
Major 6th5/3−15.6
Harmonic 7th7/4−31.2
Minor 7th9/5+17.6
Major 7th15/8−11.7
Octave2/10

Equal temperament vs. pure intonation

Equal temperament divides the octave into twelve identical half steps so a keyboard can play in every key. The cost is that thirds and sixths beat noticeably. Ensembles that sustain chords, such as wind bands, brass and saxophone sections, string quartets and choirs, adjust toward pure intervals so chords lock and ring. Practicing against a just-intonation drone trains your ear to hear and place those adjustments.

Frequently asked questions

What is pure intonation?

Pure (or just) intonation tunes each note of a chord to a simple whole-number frequency ratio above the root, such as 3:2 for the fifth and 5:4 for the major third. The chord then rings without beats, unlike equal temperament, where every half step is exactly 100 cents and most intervals are slightly out of tune.

How many cents should I lower a major third?

A just major third (5:4) is 13.7 cents lower than an equal-tempered major third. A minor third (6:5) is 15.6 cents higher, and a pure fifth (3:2) is only about 2 cents higher.

How does the tuner know which note is the root?

Every time you add or remove a note, MVB Tuner analyzes the pitch set and names the chord, from simple triads up to chords like C13♯11♭9 or G13sus♭9. The root turns purple and stays at equal-tempered pitch; every other note is retuned relative to it.

Should the dominant seventh be tuned with 7/4?

The 7/4 harmonic seventh (31.2 cents flat of equal temperament) is the most consonant seventh and is the default here. Switch to 9/5 (17.6 cents sharp) for a brighter, more conventional minor seventh.

Is MVB Tuner an alternative to Tonal Energy Tuner?

It covers the two features many ensemble musicians use most in Tonal Energy, the tuner and the just-intonation drone, and adds automatic chord-root detection. It runs free in any modern browser on iPhone, Android, Mac and PC. MVB Tuner is an independent project and is not affiliated with Tonal Energy.

Does it work offline and on my phone?

Yes. Open it once and you can add it to your home screen; it then loads without a connection. The microphone tuner needs permission in your browser.