A Lydian Mode on the Keyboard: Four Black Keys and One Bright Note

Play an A major chord, then add a D# on top and hold it. Something lifts. The music stops sitting on the ground and starts hovering, as if gravity has been switched off for a moment. That one raised note is the whole personality of A Lydian, a scale that sounds bright like major but never quite settles down. It is the sound of wide skies and slow camera pans, and once you can hear that D# you will recognise it everywhere.

Seven keys, mostly black

Here are the notes of A Lydian: A, B, C#, D#, E, F#, G#. On a piano, that is three white keys (A, B and E) and four black keys (C#, D#, F# and G#). Your hand spends most of its time up on the raised black keys, which gives the scale a pleasantly compact, curved feel under the fingers.

A whole step means skipping one key, black or white, so you land two keys away. A half step is the smallest move in Western music, from one key to the very next one with nothing in between. The pattern for Lydian is:

W - W - W - H - W - W - H

Start on A and follow it. A to B is a whole step. B to C# is a whole step (you skip C). C# to D# is a whole step. Then comes the first half step: D# to E, black key straight to its white neighbour. E to F# and F# to G# are whole steps, and G# to A closes the scale with the second half step.

Notice what is missing. The piano's two natural white-to-white half steps, B to C and E to F, are both avoided. C and F have been lifted to C# and F#. Both half steps in A Lydian run from a black key up to a white one, D# to E and G# to A, and those two little slides pull upward. That upward lean is part of why the scale feels like it is rising.

Why D# and not Eb

You might wonder why the fourth note is called D# when the same piano key could be called Eb. It is a fair question, and the answer is simple. A scale uses each letter name exactly once: A, B, C, D, E, F, G, each with whatever sharp or flat it needs. If we called it Eb, we would have two E's (Eb and E) and no D at all, which makes the scale very hard to read on paper.

Also, D# tells you exactly what the note is doing. It is the fourth note of the scale, raised. In theory terms that is the augmented 4th, written #4 in the formula: 1, 2, 3, #4, 5, 6, 7. Compare it with plain A major, which has a D natural. Everything else is identical. Change one note, D up to D#, and A major becomes A Lydian.

A borrowed key signature

A key signature is the set of sharps or flats written at the start of a piece of music so you don't have to mark them on every note. A Lydian has no signature of its own. It borrows from E major, which uses four sharps: F#, C#, G# and D#.

That is because A Lydian contains exactly the same seven notes as E major (E, F#, G#, A, B, C#, D#). The difference is where home is. In E major, everything resolves to E. In A Lydian, the music circles back to A and treats A as the place of rest. Same keys on the piano, different centre of gravity. Musicians call E major the parent scale of A Lydian.

The chords, and the one that gives it away

Stack every other note of the scale and you get these chords:

• I: A (A-C#-E) / Amaj7
• II: B (B-D#-F#) / B7
• iii: C#m (C#-E-G#) / C#m7
• #iv°: D#dim (D#-F#-A) / D#m7b5
• V: E (E-G#-B) / Emaj7
• vi: F#m (F#-A-C#) / F#m7
• vii: G#m (G#-B-D#) / G#m7

Look at the second chord. In an ordinary major key, the chord on the second note is minor. Here it is B major, because it contains that D#. Moving from A to B and back is the signature Lydian move. Two major chords a whole step apart, neither one quite asking to resolve to the other.

On piano, try this: left hand plays A, right hand plays an A major triad. Then keep the left hand on A and move the right hand up to a B major triad (B-D#-F#). Go back and forth slowly. Over that steady A in the bass, the B chord sounds like Amaj7 with a raised fourth floating above it, which is the entire mood of the scale in two shapes.

For a fuller loop, try Amaj7 - B - G#m7 - Amaj7. The G#m7 adds a touch of shade before the return home.

How a melody behaves

Sing or play up the scale and you will feel the D# want to slide up a half step to E. That pull is useful, but be careful with it. If your melody keeps resolving D# to E and resting there, the ear may decide E is home and you will drift into E major.

To keep the Lydian colour, let the D# linger and then return to C# or step down toward A. Land phrases on A, C# or E, the notes of the home chord. Use D# as a bright, suspended colour, held over an A in the bass, rather than as a note that has to go somewhere. Singers often find that a long held D# over an A drone gives an almost weightless feeling.

This is why Lydian turns up so often in film and television music, where composers want wonder or a sense of lift without sadness. The famous theme from The Simpsons is a well-known Lydian melody, written in a different key but built on the same raised fourth.

For guitarists

Your A roots sit at the open A (5th) string, plus frets 12 and 24 on that string, and at frets 5 and 17 on the low E (6th) string. A good start is to let the open A string ring as a drone and play the scale on the higher strings above it, leaning on D# to hear the lift. Then move to the 5th fret of the low E string and play the A-to-B chord vamp there.

Something to try today

Hold an A low on the piano with the sustain pedal down. With your right hand, play only C#, D# and E, very slowly, in any order. Stop on the D# and let it ring for four full seconds over the A. That hovering moment, bright but unresolved, is the sound you are learning to write with.

For the bigger picture, read The Lydian Mode.