Chords » C# Minor 9th Flat Fifth

Symbols:C#m9b5
Scale Degree Formula:1-♭3-♭5-♭7-9
Interval Stack:m3 + m3 + M3 + M3
Notes:C#, E, G, B, D#
Hear this chord:▸ Guitar

Construction

Using the scale degree formula, we first start with the C# major scale, and number each note in the scale starting from 1 - these are the scale degrees. Next, we use the scale degree formula, in this case 1-♭3-♭5-♭7-9, to select notes from our enumerated scale. When a chord requires notes that are not in the scale, this is indicated with a flat (♭) or a sharp (#) along with the scale degree; a ♭3, for instance, would be one half-step down from the 3rd scale degree.
Alternatively, we can use the interval stack to construct our chord. With this approach, we first start with the lowest note of the chord (C#), then move our first interval (m3), which brings us to our second note in the chord (E). We repeatedly apply each of the remaining intervals in the stack to get the full list of notes for our chord.
The diagram below shows how both the scale degree formula and interval stack methods result in the same selection of notes:
C#1D♭2D#2E♭3F3F#4G♭5G#5A#5Bb6B♭7C7C#8D♭9D#9m3m3M3M3

Frequencies and Harmonics

On acoustic instruments (such as guitar or piano), a single played note will result in more than a single sounded frequency. There's a lot of complexity here, but at its simplest, the fundamental (eg: A4 = 440Hz) will sound, as well as a number of harmonies, which are multiples of that frequency.
The graph below presents a simplied representation of the sounds and relative amplitudes that are sounded when this chord is played. The exact instrument, and even how the chord is played, can vary things dramatically, but this can give you an understanding of certain sounds you may hear when playing a chord.
Each fundamental and its harmonies are given a different color. The height of the bar represents the amplitude (volume) of the frequency, and the position (left-to-right) represents the frequency of the sound (further to the right means higher). Finally, the grid-lines represent notes in 12-tone-equal-temperment (notes used in traditional western music).
frequencyamplitudeC2C3C4C5C6C7
From these frequencies, we can determine harmonics that sound when we play the notes of a chord. These harmonies are listed below, along with the frequencies contributing to each. It's worth noting that these frequencies won't all be the same for higher harmonies, and some harmonies will be flat, sharp (or both).

Primary chord notes

These 'harmonics' are the primary notes of the chord.
B
Frequencies (HZ):247, 494, 494, 970, 980, 988, 989, ...
Intonation:Mixed — Sometimes flat, sharp, or in-tune. Cents off range from -31 to 2.
C#
Frequencies (HZ):139, 277, 554, 1109, ...
Intonation:In tune
D#
Frequencies (HZ):311, 622, 1235, 1245, 1247, ...
Intonation:Mixed — Sometimes flat, sharp, or in-tune. Cents off range from -14 to 4.
E
Frequencies (HZ):165, 330, 659, 1319, ...
Intonation:In tune
G
Frequencies (HZ):196, 392, 784, ...
Intonation:In tune

Significant harmonics

Harmonics with a prominent presence in the chord.
D
Frequencies (HZ):588, 1154, 1176, ...
Intonation:Mixed — Sometimes flat, sharp, or in-tune. Cents off range from -31 to 2.
F#
Frequencies (HZ):741, 1482, 1483, ...
Intonation:Mixed — Sometimes flat, sharp, or in-tune. Cents off range from 2 to 4.
G#
Frequencies (HZ):416, 824, 832, ...
Intonation:Mixed — Sometimes flat, sharp, or in-tune. Cents off range from -14 to 2.

Lesser harmonics

Harmonics that are less prominent, but present nonetheless.
Bb
Frequencies (HZ):933, ...
Intonation:In tune
F
Frequencies (HZ):693, 1372, 1386, ...
Intonation:Flat — the lowest frequency sounded for this note is 31 cents flat.

Similar Chords

The following chords are similar to this chord and may be a suitable replacement in certain scenarios.

Chord TypeChords
7th Suspended Four Flat 9thF#7sus4b9
Dominant 7th Flat 9thD#7b9
Dominant 7th Flat Five Flat 9thD#7b5b9
Dominant 7th Flat Nine Flat ThirteenthD#7b9b13
Dominant 7th Flat ThirteenthD#7b13
Dominant 7th Sharp FifthD#7#5
Dominant 7th Sharp Five Flat 9thD#7#5b9
Dominant 7th Sharp Five Sharp 9thD#7#5#9
Dominant 9thA9
Dominant 9th Flat FifthC#9b5, A9b5
Dominant 9th Sharp FifthD#9#5, B9#5
Half-Diminished 7thC#m7(b5)
Minor 6thEm6
Minor 9thC#m9
Minor Major 7thEmM7
Minor Major 9thEmMaj9
Minor Six-NineEm6/9

Associated Scales

This chord can be found in the following scales.

ScaleRoots
Dorian b5C#
Harmonic MajorB
Harmonic MinorG#
Ionian #5B
Locrian bb7Bb
Locrian ♮6Bb
Lydian #9E
Lydian Augmented #2G
Lydian b3E
Mixolydian b2F#
Phrygian DominantD#
Phrygian b4D#
Super-Locrian bb7G
Ukrainian DorianC#

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