Some Important Points About Extensions, Suspensions & Alterations
Firstly, it doesn’t matter where the extension is placed in any voicing, it can be above or below the b7. It is still an extension.
Take the Herbie Hancock Minor Voicing for example, the 11th is right in the middle of the voicing.
The extension, suspension, or alteration can be above, or below the b7 and that won’t change anything.
It’s the presence of the tones that defines the chord quality, not how they are laid out or arrangement. ie. voiced.
That’s what makes harmony so fun in my opinion… because you have lots of creative freedom to voice and arrange the tones of the chord.
Another Important Point…
An important rule to remember is that if the 7th is in the chord, the 2, 4 & 6 are referred to as the 9, 11, & 13.
An exception is the a 69 chord which contains the major 6th and the 9th.
Now onto Sus Chords - also known as Suspended Chords:
Sus chords are slightly different, a sus chord is dominant in nature because of the b7.
Generally, the 4th - also called the suspended 4th - will replace the 3rd.
The possible sus chords for C7 are:
C7sus - which contains the root, 4th and 7th
C9sus - which contains the root, 4th, 7th and 9th
C13sus - which contains the root, 4th, 7th, 9th and 13.
Sometimes you may see C7sus4 - but the 4 is not always added, I don’t add it personally, but some musicians do.
Also remember that when you see “C7sus” or “C7sus4” on a lead sheet, you are not limited to the just the b7th, you should experiment with the 9 and the 13, see how they sound to your ears and add them at your discretion. Remember these tones don’t need to be voiced above the b7… thay can be anywhere!
Temporary Stepping Stones
The nice things with Sus chords is that you can play them for virtually any dominant chord you come across. In effect, it’s a reharmonisation.
I like to look at it as a ’temporary stepping stone’ between the ii-7 and the V7 chord.
I use that device a lot in my solo piano playing. It’s very Bill-Evans-esque
Generally, The 3rd is replaced by the 4th:
A final note on sus chords, there are some voicings where you can have the 3rd in a sus chord, I play one in this tutorial for the G7 in bar 4: https://www.pianogroove.com/jazz-piano-lessons/easy-to-love-tutorial-cole-porter/ - one thing that makes this voicing work is that the Major 3 and the suspended 4th are voiced an octave apart, this removes some of the dissonance from playing them right next to each other.
Because it’s a sus chord. If you raised the 4th to the #11, it would no longer be a sus chord.
A sus chord must have the natural 4 and b7 for it to be a sus chord.
The 4th is a suspension which gives a very bright, floating, unresolved quality.
The 4th naturally wants to resolve down to the 3rd, to then create a dominant 7 chord.
Regarding the #11:
If you were playing a dominant 7 chord, it would contain the major 3 and b7, and in that case it would be more common to raise the 4th to get the #11.
Otherwise, you have a half step interval between the 3 and the 4 which is dissonant.
Also, understand that the #11 is an alteration. This is like an enhancement, or ‘garnish’ to the basic dominant sound of R-3-b7. Along with the other alterations (b9 #9 and #5) which can be added in at the discretion of the musician.
Alterations won’t always work, and sometimes just the plain old dominant 7th shell (Root maj3 and b7) will sound just fine.
The #11 is a beautiful tone to use, but also very rich, and so you certainly wouldn’t want to include it in every dominant 7 chord you play. Variety is key.