Fb Locrian Mode: Notes, Chords and How to Play It
Fb Locrian is the darkest, most restless of the seven modes, and in this key it also comes with some of the strangest-looking spelling you'll ever see. Don't let that scare you off. Underneath the double flats is a sound you can play right now, starting on your open low E string, and learning it will teach you a lot about how tension works in music. Let's get it under your fingers.
The Notes of Fb Locrian
A mode is a scale that uses the same notes as a major scale but starts and finishes on a different note, which gives it a completely different mood. Fb Locrian has seven notes:
Fb, Gbb, Abb, Bbb, Cbb, Dbb, Ebb
The symbol "bb" is a double flat. A flat lowers a note by one fret, and a double flat lowers it by two frets. So Gbb is the note G pushed down two frets.
These are exactly the same notes as the Gbb major scale (Gbb, Abb, Bbb, Cbb, Dbb, Ebb, Fb). The only difference is where you treat "home". In Fb Locrian, everything starts on Fb and tries to settle back on Fb.
A friendly word about the spelling
If this looks like a typo, you're in good company. Fb Locrian is what musicians call a theoretical key. Written out properly, its parent scale needs a key signature of 13 flats, which is far more than any real piece of sheet music would use. So in practice, players write it as E Locrian, which has a key signature of just 1 flat and sounds exactly the same. Fb and E are the same pitch on your guitar. You're not learning a weird extra scale; you're learning E Locrian with a different name tag. Knowing both spellings simply helps you understand the theory behind it.
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
Starting on Fb, here's how it plays out:
- Fb up a half step gives Gbb
- Gbb up a whole step gives Abb
- Abb up a whole step gives Bbb
- Bbb up a half step gives Cbb
- Cbb up a whole step gives Dbb
- Dbb up a whole step gives Ebb
- Ebb up a whole step brings you back to Fb
A great way to feel this is to play it all on one string. Start on the open low E string (that's your Fb) and follow the pattern up the neck: 1 fret, 2 frets, 2 frets, 1 fret, 2, 2, 2. You'll land on the 12th fret, Fb again, an octave higher.
The formula describes each note by its distance from the root: 1, b2, b3, 4, b5, b6, b7. That's a minor 2nd, minor 3rd, perfect 4th, diminished 5th, minor 6th and minor 7th above the root.
Why It Sounds So Unsettled
Locrian's personality comes from one note: the flat 5th. In Fb Locrian, that's Cbb.
In most scales, the 5th is a rock-solid note. It's what makes a power chord sound strong and stable. Locrian lowers that 5th by a fret, and suddenly the floor drops out. The chord built on the root becomes diminished, a tense, slightly eerie sound that never quite feels finished.
The other ingredient is the flat 2nd, Gbb, sitting just one fret above the root. That tight, grinding half step gives Locrian its dark, almost menacing edge. You'll hear this kind of sound in heavier styles of rock and metal, where riffs lean on that half-step rub against a low open string.
What to listen for: play your open low E (Fb), then the note six frets up on the same string (Cbb). Hear how uneasy that gap is? That's the heart of Locrian.
Chords From Fb Locrian
If you stack notes from the scale in thirds, skipping every other note, you get these chords:
- i°: Fbdim (Fb-Abb-Cbb) / Fbm7b5
- bII: Gbb (Gbb-Bbb-Dbb) / Gbbmaj7
- biii: Abbm (Abb-Cbb-Ebb) / Abbm7
- iv: Bbbm (Bbb-Dbb-Fb) / Bbbm7
- bV: Cbb (Cbb-Ebb-Gbb) / Cbbmaj7
- bVI: Dbb (Dbb-Fb-Abb) / Dbb7
- bvii: Ebbm (Ebb-Gbb-Bbb) / Ebbm7
Notice the home chord, Fbdim, is diminished. That's why Locrian is rarely used for whole songs: there's no comfortable place to land.
A simple progression to jam over
The most Locrian-sounding move is going between the home chord and the chord one half step above it:
Fbm7b5 to Gbbmaj7, two bars each, over and over.
That half-step shift captures the mode perfectly. For a little more variety, try Fbdim - Gbb - Fbdim - Ebbm. Record it or loop it, then improvise over the top using the scale, and keep coming back to Fb and Cbb to hear the tension.
Finding the Root on the Neck
On a standard-tuned 6-string guitar, your root note Fb lives here:
- Low E (6th) string: frets 0, 12 and 24
- A (5th) string: frets 7 and 19
The open low E string is your best friend for this mode. You can let it ring as a drone, a constant low note underneath, while you play the scale above it. That makes the flat 2nd and flat 5th jump right out, so you really hear the mode's colour rather than just running notes.
For a second position, use the 7th fret of the A string as your anchor and build the scale around it.
Your Practice Plan
Spend five minutes today with the open low E ringing. Play the scale slowly up one string, saying the note names as you go. Then loop that Fbm7b5 to Gbbmaj7 change and make up short phrases that end on Cbb, then on Fb, and notice how differently each one feels. Keep it slow, keep it dark, and enjoy how strange it sounds. That strangeness is exactly the point.
For the bigger picture, read The Locrian Mode.