Improvising over static sus4 chords

In my last post I explained the structure of suspended fourth (sus4) chords. Now I would like to say a few words about improvising over these chords. By 'static', I mean sus4 chords that do not resolve to another chord (usually a fifth below). These static chords are used in a modal way with no need to resolve. As I mentioned in my last post, a great example for such static sus4 chords is Herbie Hancock's composition Maiden Voyage.

I would like to focus on pentatonic scales because they sound great over suspended chords, and most guitar players already know them. As you probably know, the most common pentatonic scales are the minor and the major pentatonic scales:

A minor pentatonic scale: a - c - d - e - g
C major pentatonic scale: c - d - e - g - a

These two scales are of course identical, they just have different roots. Let's have a look at the notes of a 7sus4 chord with added tensions 9 and 13, e.g. with root D:

D13sus4 = Am9/D = d - g - a - c - e - b

(If you have trouble understanding this, just check my previous post).

If you compare these notes to the notes of the A minor pentatonic scale, you'll notice that the scale contains all chords tones except for the 'b'. That makes this scale is a great choice for improvising over a D13sus4 chord (and over all other D7sus4 chords with or without added tensions). If you want to use a scale that also contains the 'b' (which is the '13' of the chord), then you'll have to exchange this note for another chord tone if you want to stick to pentatonic scales (because they only contain five notes, whereas the D13sus4 chord has six notes). The E minor pentatonic scale adds the 'b' at the expense of the 'c':

E minor pentatonic scale: e - g - a - b - d

Listen to the next two sound samples to hear how those two scales sound over a D13sus4 chord:

A minor pentatonic scale over D13sus4:

E minor pentatonic scale over D13sus4:

I hope you agree that they both sound good.
Let's summarize: if you want to play pentatonic lines over a suspended fourth chord (e.g. D7sus4, D9sus4, D13sus4), use a minor pentatonic scale with the root either a perfect fourth below or a major second above the root of the chord. Over a D7sus4, this gives A minor and E minor pentatonic, respectively.

I'd recommend to you to use this pentatonic approach to improvise over Maiden Voyage by Herbie Hancock. The song starts with 4 bars of D13sus4 (Am9/D) followed by 4 bars of F13sus4 (Cm9/F). These 8 bars are then repeated. For a start, just use these 16 bars for playing some pentatonic lines. So what are the scales? As mentioned before, over D13sus4 you can use either the A minor or the E minor pentatonic scale. Over F13sus4 you use the C minor or the G minor pentatonic scale. Enjoy!

Sus4 Chords

I decided to write a few lines about sus4 (suspended fourth) chords because I found that students can get quite confused about them, especially because of the large number of different symbols that are used for these chords in lead sheets.

In sus4 chords, the third of a (major or minor) triad is replaced by the fourth scale tone, i.e. by the note which is a perfect fourth above the root note. OK, here's an example: in a Dsus4 chord, the third of the chord (either F# in a D major triad, or F in a D minor triad) is replaced by a G, which is a perfect fourth above the root D: Dsus4 = d - g - a
Many of you guitar players have probably discovered this chord: XX0233

OK, that was simple, and there is usually not much confusion about such basic sus4 chords. However, it gets a bit more complicated when tensions are added, e.g. D7sus4, D9sus4 or D13sus4. (There is no D11sus4 for because the 11 and the 4 are the same notes.) These chords sound really nice because of their open character. They can either function as dominant chords resolving to a tonic chord, such as in the progression D7sus4 - Gmaj7, or they can be used as static chords with no need to resolve. Check out Herbie Hancock's Maiden Voyage for an example of static sus4 chords.

Let's now take a closer look at sus4 chords with added tensions:

D7sus4   = d - g - a - c
D9sus4   = d - g - a - c - e
D13sus4 = d - g - a - c - e - b

Looking at the chord notes of D9sus4, it turns out that the notes above the root note 'd' spell out an inversion of an Am7 chord: a - c - e - g. So an D9sus4 is equal to an Am7/D (Am7 over D as bass note). Sometimes the note 'a' is omitted, which gives a C/D chord (C major triad over D). For D13sus4 we get an extra note 'b', and the notes above the root spell out an Am9 chord: a - c - e - g - b. So we get D13sus4 = Am9/D, or - if the 'a' is left out - we get Cmaj7/D.

To sum up, we get the following equivalent chord symbols:
D9sus4   = Am7/D ≈ C/D
D13sus4 = Am9/D ≈ Cmaj7/D

These chords can be used interchangeably and they all have the same open sounding character. Here are some useful voicings for these chords:

D9sus4: X 5 5 5 5 5; 10 X 10 9 8 X; X X 12 12 13 12; X 5 X 5 5 3; 10 X 10 12 10 12
D13sus4: X 5 5 5 5 7; 10 X 10 12 12 12

And of course, if you play with a bass or keyboard player, you don't necessarily need to play the root on the guitar, so can use any voicing of C, Cmaj7, Am7 or Am9 to get the right sound. Have fun experimenting with these chords!

In the next post I talk about an easy way to improvise over these chords.