Ultralocrian bb6 Mode on Guitar: Notes, Chords & Examples

  • May 21, 2026

The Ultralocrian bb6 mode is one of the darkest, most unstable sounds you can put under your fingers on guitar.

It has a tense, collapsed quality: diminished, chromatic, alien, and almost “wrong” in a useful way. If modes like Phrygian or Locrian sound dark, Ultralocrian bb6 sounds even more extreme.

This is not a casual campfire mode.

It works best for:

  • Progressive metal riffs
  • Fusion “outside” lines
  • Horror soundtrack textures
  • Diminished chord vamps
  • Tense transitions and modal modulation
  • Experimental songwriting

Because of its double-flat intervals, this mode is more advanced than common modes like Dorian or Mixolydian. But on guitar, it becomes very playable once you focus on the sound instead of getting stuck in the spelling.

Formula

The interval formula for C Ultralocrian bb6 is:

1 b2 b3 b4 b5 bb6 bb7

Using interval names:

P1 m2 m3 d4 d5 d6 d7

That gives the mode this highly compressed, diminished sound.

The most important color tones are:

  • b2 — immediate tension
  • b4 — enharmonically sounds like a major 3rd, but functions differently
  • b5 — diminished/tritone instability
  • bb6 — enharmonically sounds like a perfect 5th
  • bb7 — enharmonically sounds like a major 6th

This is why the mode can feel both diminished and strangely “split” between minor, dominant, and altered colors.

Notes in C

The correctly spelled notes in C Ultralocrian bb6 are:

C Db Eb Fb Gb Abb Bbb

For guitar players, the enharmonic pitch names are often easier to visualize:

C Db Eb E Gb G A

Important note:

  • Fb sounds like E
  • Abb sounds like G
  • Bbb sounds like A

So while the theoretical spelling is:

C Db Eb Fb Gb Abb Bbb

Your fretboard shape will look like:

C Db Eb E Gb G A

Both are useful. Use the formal spelling for theory and chord naming. Use the enharmonic notes for finding the mode quickly on guitar.

The Chord That Defines the Mode

The defining chord of C Ultralocrian bb6 is:

Cdim7

Spelled from the mode:

C Eb Gb Bbb

That gives you:

1 b3 b5 bb7

This chord captures the core personality of the mode because it contains the root, minor 3rd, diminished 5th, and diminished 7th. In other words, it gives you the fully diminished sound at the center of the mode.

A fuller modal chord would be:

Cdim7(b9, b11, bb13)

Using the mode tones:

C Eb Gb Bbb Db Fb Abb

But that is very dense and dissonant. For practical guitar use, start with Cdim7, then add color tones like Db, Fb/E, or Abb/G as melodic or riff notes.

A simple Cdim7 guitar voicing:

E|---x---
B|---4--- Eb
G|---2--- Bbb/A
D|---4--- Gb
A|---3--- C
E|---x---

This chord immediately gives you the tense, symmetrical, unstable sound that makes the mode useful.

Chord Progressions

Because C Ultralocrian bb6 is so unstable, it usually works better as a vamp, riff environment, or outside color than as a traditional functional chord progression.

Here are three practical progressions.

Progression 1: Diminished Tension Vamp

Roman numerals:

i°7 - bII° - i°7 - bIII°

Chords in C:

Cdim7 - Dbdim - Cdim7 - Ebdim

Mood:

This progression sounds claustrophobic, tense, and cinematic. The half-step movement from Cdim7 to Dbdim emphasizes the b2, which is one of the most aggressive notes in the mode.

Use this for:

  • Horror-style riffs
  • Dissonant prog interludes
  • Fusion outside vamps
  • Tension before resolving into C minor or another darker key

Progression 2: Diminished to bV Minor

Roman numerals:

i°7 - bVmin - bIII° - bII°

Chords in C:

Cdim7 - Gbm - Ebdim - Dbdim

Mood:

The Gbm chord is especially useful on guitar because it gives the progression a heavier, more riff-friendly center. The move from Cdim7 to Gbm highlights the diminished 5th relationship.

This can sound:

  • Mechanical
  • Dark
  • Progressive
  • Unsettled
  • Good for odd-meter metal riffs

Try palm-muting the roots and using the full chords as accents.

Progression 3: C Pedal Vamp

Roman numerals:

i°7 - bII°/1 - bVmin/1 - i°7(add b2)

Chords in C:

Cdim7 - Dbdim/C - Gbm/C - Cdim7(add Db)

Mood:

Keeping C in the bass makes the mode feel more centered. This is useful because the scale is naturally unstable and can easily sound like it has no home.

The pedal tone makes it feel more like a deliberate modal sound instead of random chromaticism.

Great for:

  • Progressive metal breakdowns
  • Ambient dissonant sections
  • Dark fusion vamps
  • Building tension before a resolution

Famous Songs and Guitarists Using C Ultralocrian bb6

There are no widely recognized guitar-based songs that are clearly and specifically written in C Ultralocrian bb6.

This is an obscure synthetic mode, and it is not commonly labeled in popular music analysis. You may hear similar sounds in music that uses:

  • Diminished scales
  • Altered dominant sounds
  • Hungarian major/minor colors
  • Chromatic metal riffs
  • Outside fusion lines

Artists commonly associated with related “outside” or synthetic sounds include:

  • Allan Holdsworth
  • Shawn Lane
  • John McLaughlin
  • Marty Friedman
  • Ron Jarzombek
  • Meshuggah-style progressive metal writers

However, it would be inaccurate to claim these players are specifically using C Ultralocrian bb6 unless a particular transcription or analysis confirms it.

A better way to think of this mode is:

C Ultralocrian bb6 is a powerful source of diminished, altered, and chromatic tension for original riffs and solos.

Use it as a creative tool rather than trying to copy a famous song.

Guitar Fretboard Shape

Here is a practical C Ultralocrian bb6 shape starting around the 8th fret.

The pitch names on the fretboard are the enharmonic versions:

C Db Eb E Gb G A
e|-----------------------------11-12-14-15-17-|
B|-----------------------13-14----------------|
G|----------------11-12-14--------------------|
D|---------10-11-13-14------------------------|
A|---9-10-12----------------------------------|
E|-8-9-11-12----------------------------------|

Remember, the theoretically correct spelling is:

C Db Eb Fb Gb Abb Bbb

But on guitar, you will physically play:

C Db Eb E Gb G A

Start slowly and listen to the half-step clusters. This mode is not about smooth major-scale comfort. It is about tension, pressure, and release.

Why Guitarists Love This Mode

Emotional Flavor

C Ultralocrian bb6 sounds dark, unstable, and dangerous.

It does not have the familiar sadness of Aeolian or the exotic darkness of Phrygian. Instead, it feels more abstract and dissonant.

The emotional character is closer to:

  • Horror
  • Anxiety
  • Suspense
  • Mechanical aggression
  • Alien landscapes
  • “Something is about to break” tension

That makes it very useful for modern progressive writing.

Riff Potential

This mode is excellent for riffs because it contains several tight, aggressive intervals:

C to Db = b2
C to Gb = b5
C to Bbb/A = bb7
Gb to G = chromatic crunch
Eb to E/Fb = chromatic crunch

Those half-step and tritone relationships are perfect for heavy guitar.

Try building riffs around:

  • C to Db
  • C to Gb
  • Eb to E
  • Gb to G
  • Cdim7 arpeggios
  • Pedal-tone C riffs

For metal, use the scale in small fragments rather than running it up and down like an exercise.

Soloing Applications

C Ultralocrian bb6 works well over:

  • Cdim7
  • Cdim7(b9)
  • Diminished vamps
  • Dark chromatic pedal tones
  • Outside lines resolving into C minor, Db, or Gbm

A useful strategy is to play short phrases from the mode, then resolve to a more stable sound.

For example:

C Ultralocrian bb6 phrase -> resolve to C minor

or:

C Ultralocrian bb6 phrase -> resolve to Db major/minor color

The mode is very tense, so resolution is your friend.

Genres Where It Works Well

C Ultralocrian bb6 fits especially well in:

  • Progressive metal
  • Technical death metal
  • Fusion
  • Experimental rock
  • Horror scoring
  • Dark ambient guitar music
  • Avant-garde jazz
  • Cinematic instrumental music

It is probably not the first choice for blues, pop, country, or classic rock unless you want a deliberately strange passing color.

Tips for Practicing

1. Practice Over a C Drone

Start with a low C drone.

You can use:

  • A looper pedal
  • A synth drone
  • A sustained bass note
  • A clean guitar loop
  • A DAW instrument

Play the mode slowly over the drone and listen to each interval.

Focus especially on:

Db = b2
Fb/E = b4
Gb = b5
Abb/G = bb6
Bbb/A = bb7

Do not rush. The goal is to hear the tension clearly.

2. Use Simple Chord Vamps

Try these vamps:

Cdim7 - Dbdim
Cdim7 - Gbm
C pedal bass with Cdim7 fragments

Keep the harmony minimal. This mode does not need busy chord changes. Too many chords can make the sound confusing.

3. Improvise With Small Fragments

Instead of playing the full scale immediately, create two- or three-note cells.

Examples:

C - Db - Eb
C - Gb - G
Eb - E - Gb
A - C - Db

Repeat them rhythmically. Move them through different strings. Add bends, slides, and palm-muted accents.

This will make the mode sound musical instead of like a theory exercise.

4. Target the Defining Intervals

When soloing, aim for the tones that give the mode its identity:

  • b2 for sharp tension
  • b5 for diminished darkness
  • bb7 for the diminished seventh sound
  • b4 and bb6 for the strange enharmonic colors

A good target phrase is:

C - Eb - Gb - A

That outlines Cdim7.

Then add color:

C - Db - Eb - E - Gb

That brings out the more unusual modal flavor.

Try This Mode in SLModes

Want to explore C Ultralocrian bb6 more deeply?

Try it in SLModes.

SLModes helps you experiment with modes using:

  • Interactive chords
  • Guitar fretboard layouts
  • Modal modulation tools
  • Scale and chord relationships
  • Negative harmony exploration

For a mode this advanced, visual tools make a big difference. You can hear the chord colors, map the notes across the neck, and test how C Ultralocrian bb6 moves into other modal sounds.

Open SLModes, choose C Ultralocrian bb6, and start building dark riffs, diminished vamps, and outside fusion lines.