I’m having a hard time “really” understanding the following slash chord:
Notes in order:
Ab Eb Gb - Db F Gb Bb
My logic is telling me it's a Gb maj7/13 / Ab, butI would like to give this chord a notation beginning with the root note "Ab". The best I came up with (so far) is Ab 7/9/11/13 (no3). I don't think this is correct. Can it be some kind of dominant sus chord (ex. 9sus4)At least it sounds like one. Dominant, sus, IV/V feel.
Is there a way to notate this chord NOT as a slash chord?
TL;DR: Ab13sus4
There are always quite a few different ways to notate a particular set of pitches as a chord symbol. And, yes, this can get fairly ambiguous once you have a large number of pitches. In the end, I think it is always important to: try to explain a chord in the simplest way possible; use some common-sense (so, if there is some easily discernible triadic element for instance, it would seem best to acknowledge it).
If you want exactly the same notes and same voicing every time, it is best to use actual notation on a stave. However, if you need to describe the pitches at any one point, for chord symbols above a part, or for analysis, for instance, you will just need to be as accurate as possible.
Personally, I like your Gb maj7/13/Ab idea. You can simplify this further: Gbmaj13 implies the major 7th and 9th (and you often miss out the 11th, which would be Cb, in a 13th chord). So this would mean Gbmaj13/Ab would work. However, I would be bothered by the fact that the root of the Gb chord is above the 13th (Eb), while this isn't incorrect, the Ab and Eb fifth at the bottom of the chord more strongly suggest some kind of Ab chord, than Gb chord (this is the common sense taking over, even if we end up with a longer chord description).
So, how about Ab13sus4? The 13th implies the 7th and 9th. Using tertian harmony, you don't really need to describe the Db as an 11th, as there is no 3rd. So it can be described as a sus4.
There are other ways to notate this chord. A couple of things to be aware of: if you ask for a 13th chord a player will often miss out the 11th, even though strict tertian harmony would suggest that a 13th implies an 11th; if you do ask for an 11th a player will usually miss out the major 3rd, as it creates a "nasty" minor 9th interval between the 3rd and 11th. So, I guess Ab13add11 would work okay. (Although I usually take an add11 to mean that you add an 11th without the 7th and 9th, here they are implied by the 13th anyway.)
For me, it is a very simple Eb minor/Ab, since in jazz performance the 7th and 9th of the minor chord are always available. This chord is a II/V7 which resolves most likely in a I, in this case Db.
Notes: (on the piano) Ab Eb Gb - Db F Gb Bb (in that order).
Gb Major 9 add 13/Ab.
Gb Major scale degrees 1,3,5,7,9 with added 13 lowest note being Ab.
From Gb Major scale: Gb, Bb, Db, F, Ab with added Eb, lowest note being Ab.
Gb being root is often doubled.
The notes of any chord can be played in any register as long as the slash note is the lowest.
