Chords » F# 7th Suspended Fourth

Symbols:F#7sus, F#7sus4, F#9sus4, F#9sus
Scale Degree Formula:1-4-5-♭7
Interval Stack:P4 + M2 + m3
Notes:F#, B, C#, E
Hear this chord:▸ Guitar

Construction

Using the scale degree formula, we first start with the F# 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 1-4-5-♭7, 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 (F#), then move our first interval (P4), which brings us to our second note in the chord (B). 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:
F#1G♭2G#2A♭3Bb3B4C♭5C#5D#5D#6E♭7P4M2m3

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, 988, 989, ...
Intonation:In tune
C#
Frequencies (HZ):277, 554, 555, 1109, 1110, ...
Intonation:In tune
E
Frequencies (HZ):330, 659, 1295, 1319, ...
Intonation:Mixed — Sometimes flat, sharp, or in-tune. Cents off range from -31 to 0.
F#
Frequencies (HZ):185, 370, 740, 741, 1480, 1482, ...
Intonation:In tune

Significant harmonics

Harmonics with a prominent presence in the chord.

Lesser harmonics

Harmonics that are less prominent, but present nonetheless.
Bb
Frequencies (HZ):925, ...
Intonation:Flat — the lowest frequency sounded for this note is 14 cents flat.
D#
Frequencies (HZ):1235, ...
Intonation:Flat — the lowest frequency sounded for this note is 14 cents flat.
F
Frequencies (HZ):1386, ...
Intonation:Flat — the lowest frequency sounded for this note is 14 cents flat.
G#
Frequencies (HZ):832, ...
Intonation:In tune

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
7th Suspended SecondF#7sus2, E7sus2, B7sus2
Added 9thEadd9, Badd9, Aadd9
Dominant 7thF#7
Half-Diminished 7thC#m7(b5)
Major 2ndE2, B2, A2
Major 6thEM6, AM6
Major 7th Flat FifthGMaj7b5, CMaj7b5
Major Added 11thF#add11, Badd11
Minor 2ndEm2, Bm2
Minor 6thEm6
Minor 7thF#m7, C#m7
Minor Added 11thF#madd11, C#madd11, Bmadd11
Minor Added 9thEmadd9, Bmadd9
Minor Six-NineEm6/9
Six-NineE6/9, A6/9
Suspended FourthF#sus, Bsus
Suspended SecondEsus2, Bsus2

Associated Scales

This chord can be found in the following scales.

ScaleRoots
BluesC#, F#
Blues MajorE, B
Blues MinorC#, G#
DorianE, C#, B, F#
Dorian b5C#
Harmonic MajorB
Harmonic MinorB
Ionian #5D
LocrianD#, C#, Bb, G#
Locrian bb7Bb
Locrian ♮6C#
LydianE, D, A, G
Lydian #9G
Lydian Augmented #2G
Lydian b3E
MajorE, D, B, A
Major PentatonicE, A
MinorC#, B, G#, F#
Minor PentatonicC#, F#
MixolydianE, B, A, F#
Mixolydian b2F#
PhrygianD#, C#, G#, F#
Phrygian DominantF#
Phrygian b4D#
Super-Locrian bb7Bb
SuspendedB, F#
Ukrainian DorianE

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