Ab Locrian Mode: Notes, Chords and How to Play It

The Locrian mode has a reputation as the strange one in the family of modes, and that reputation is earned. It is dark, tense and restless, and it never quite lets you relax. That is exactly why it is worth learning: once you can hear and play it, you have a sound for unease, suspense and grinding heaviness that no other mode gives you. In this guide we will look at Ab Locrian, see where its notes come from, find out what gives it that uneasy flavour, and get it under your fingers on the guitar.

The notes of Ab Locrian

Here are the seven notes of Ab Locrian:

Ab, Bbb, Cb, Db, Ebb, Fb, Gb

If that looks like a wall of flats, don't worry. You haven't misread anything, and you don't need to panic about Bbb or Ebb. A flat sign (b) means lower the note by one fret. A double flat (bb) simply means lower it by two frets. So Bbb is just B lowered two frets. These spellings look odd on paper, but on the fretboard they are ordinary notes you already know how to play.

Musicians often use numbers to describe a scale, comparing each note to the major scale. Ab Locrian's formula is 1, b2, b3, 4, b5, b6, b7. In plain words: a root, a minor 2nd, a minor 3rd, a perfect 4th, a diminished (flattened) 5th, a minor 6th and a minor 7th. Almost everything is lowered, and that is a big part of why it sounds so dark.

How the step pattern builds the scale

Every scale is built from a pattern of steps. A half step (H) is the distance of one fret. A whole step (W) is two frets. Locrian's pattern is:

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

Start on Ab and follow it along one string:

• Ab, up a half step (1 fret) to Bbb
• Bbb, up a whole step (2 frets) to Cb
• Cb, up a whole step to Db
• Db, up a half step to Ebb
• Ebb, up a whole step to Fb
• Fb, up a whole step to Gb
• Gb, up a whole step back to Ab, an octave higher

Try this on a single string. It is a great way to see the shape of the mode, and you will notice that very first move is just one fret. That cramped half step right off the root is the first hint of tension.

Why it sounds so unsettled

The note that really defines Locrian is the flat 5th. In Ab Locrian, that is Ebb.

Here is why it matters. In most scales, the 5th is a rock-solid note. It is what makes a power chord sound strong and stable. Locrian lowers that 5th by a fret, and suddenly the foundation wobbles. The chord built on the root becomes diminished (a tight, tense chord made of stacked minor 3rds), so the home chord itself never feels at rest.

When you play, lean on Ebb against the Ab root and listen. You will hear a sour, hanging quality, like a question that never gets answered. That is the Locrian sound.

Where it comes from, and the spelling note

Every mode borrows its notes from a major scale, called its parent scale. Ab Locrian uses the same notes as Bbb major (Bbb, Cb, Db, Ebb, Fb, Gb, Ab), just starting and resolving on Ab instead. Bbb major has a key signature of 9 flats, which is more than any normal key signature can hold.

That is why Ab Locrian is called a theoretical key: writing it out properly needs double flats. In practice, musicians nearly always write it as G# Locrian (key signature 3 sharps) instead. It sounds exactly the same, and your fingers play exactly the same frets. So if you see G# Locrian in a book or chart, you are looking at the same sound with friendlier spelling. Nothing about your playing changes.

Chords from Ab Locrian

Build a chord on each note of the scale and you get this family:

• i°: Abdim (Ab-Cb-Ebb) / Abm7b5
• bII: Bbb (Bbb-Db-Fb) / Bbbmaj7
• biii: Cbm (Cb-Ebb-Gb) / Cbm7
• iv: Dbm (Db-Fb-Ab) / Dbm7
• bV: Ebb (Ebb-Gb-Bbb) / Ebbmaj7
• bVI: Fb (Fb-Ab-Cb) / Fb7
• bvii: Gbm (Gb-Bbb-Db) / Gbm7

The most Locrian move of all is going between the home chord and the chord just one fret above it: Abdim to Bbb. That half-step rub is the mode's signature.

A progression to jam over

Try looping this, two bars each:

Abm7b5 | Bbbmaj7 | Dbm7 | Abm7b5

Record it or play it slowly, then improvise using the notes of Ab Locrian. Keep coming back to Ab when the chord returns to Abm7b5, and lean on Ebb to bring out that dark edge. Don't expect it to sound resolved. It isn't supposed to.

Finding the root on the neck

On a standard-tuned 6-string guitar, your Ab root lives here:

• Low E (6th) string: frets 4 and 16
• A (5th) string: frets 11 and 23

Fret 4 on the low E string is a comfortable starting point. Put your finger there, then build the scale using the step pattern, moving across to the next strings as it feels natural. Always know where your root is. It is your anchor in a mode that is otherwise trying to pull you off balance.

For practice this week, spend five minutes a day just on the root and the flat 5th: play Ab at fret 4, then find Ebb and let the two ring together. Once that sound is in your ears, add the rest of the scale over the progression above. Go slowly, listen hard, and enjoy the tension. Locrian rewards players who stop fighting its restlessness and start using it.

For the bigger picture, read The Locrian Mode.