EbMaj7(#5)

Tannin

How does this make sense? Yes, I know jazz players use this term for the chord, but why?

Chords are named for their main notes in order:

* 1st: the main pat of the name (Eb or A). This is so important that even where there is no root played we still say something like "C#7 (no root)".
* 3rd: second in importance, this determines whether the chord is major or minor. We assume major unless otherwise stated, or where that is clearly implied another way (as discussed below).
* 5th: third in importance. We don't generally mention the 5th, we assume that it is perfect, but in those (moderately uncommon) instances where the 5th is not perfect, we name the chord "augmented" or "diminished". These terms also imply the appropriate 3rd - e.g., a diminished chord always has a flat 3rd and we don't need to say "C minor diminished", just "C diminished".
* 7th : last of the four main determinants of a chord name but always mentioned where present. We assume a minor (flat) 7th unless specified otherwise.
* Others: last of all, if there are any other notes we want to indicate, we add them on to the end of the chord name. Hence "D add 4" or "Cm6" or (where a 7th is present) "E9".

According to the standard rules of chord naming (which I think I've done reasonable justice to above) we can certainly have an "Eb augmented Major 7th". But Eb Major 7th #5? Give me a break! It's an augmented chord all day long. Why not call it that?

viz

I think they’re both pretty good names for it. The thing I would say is that it could depend on context. The aug chord thrives best as a dominant, but with the major 7, it’s pretty likely not to be one. So given that it’s likely a tonic chord, the maj7 #5 could be better. 

Actually it’s quite an unusual chord anyway! Is it part of 3rd mode of melodic minor? Or just an isolated chord you’re thinking about?

Tannin

I'm looking at it as the 3rd degree of the harmonic minor scale, Viz. So essentially what you guessed. 

viz

Ah OK, so yep I reckon #5 is acceptable. I also think that chord is very often used as a minor/major chord in 1st inversion (à la James Bond). So really a tonic chord. So that augmented or sharp 5 would really be the major 7th, and the chord would be called a CminMaj9 (no root) or something!

I do know what you mean though. I dislike many chord naming conventions, they can be so unmusical!

Brad

Tannin said:

How does this make sense? Yes, I know jazz players use this term for the chord, but why?

Because it is a major7 where the 5 has been raised a semitone  

Slightly less flippantly though (and I can only speak from my perspective), if I was given a chart with lots of chords on - say 2 chords per bar at a pretty fast tempo, I would certainly appreciate seeing Eb∆7#5 (or possibly better still G/Eb) as apposed to Eb Augmented Major 7th. Even reducing that down to Eb+∆7, from a visual perspective feels clunky and not particularly intuitive from my perspective.

You've got good grounds for calling it that, but for me Eb∆7#5 is much more descriptive, particularly in the heat of the moment. I just raise the 5th of any give ∆7 voicing I'm playing at a given moment, less mental gymnastics. That's my reasoning behind your question of "why?"

Tannin

Makes sense Brad. Thanks. (It still annoys me though. Why not call it what it is?)

Keefy

Tannin said:

Makes sense Brad. Thanks. (It still annoys me though. Why not call it what it is?)

I seem to recall that the practice of referring to an augmented fifth as ‘sharp’ originated with our friends across the pond. It doesn’t bother me because I know what they’re trying to say, bless ’em.

Brad

Tannin said:

Makes sense Brad. Thanks. (It still annoys me though. Why not call it what it is?)

Because it is that as much as it’s an Augmented∆7. As @viz ; said, I think it’s a thing of context mostly, and has just become commonplace. It’s often used as a substitute for a plain maj7 chord in order to create tension over what is a pretty “bland” sound . So it’d be easier think and say ∆7#5 rather than Augmented∆7 to replace a Maj7 chord. Also, the 5th is a note ripe for altering in Dominant chords, so I guess it’s a way of keeping as much consistency as possible across chord types?

I’d wager the other aspect is from an improv perspective where it’d probably be thought more as from Melodic rather than Harmonic minor. 

For Eb∆7#5 the to go to scale would be Lydian Augmented Eb F G A B C D (1 2 3 #4 #5 6 7).
The #4 is a safer note choice over a ∆7 type chord rather than the P4 of the Harmonic Minor mode (Major/Ionian#5?) Eb F G Ab B C D. Granted it completely works with the way you want prefer to name it as well. But if it’s a substitute for a plain old maj7 chord?

I dunno, just my take on it. 

 
Also as @Keefy ; says, it’s an Americanism and Americanisms tend to stick whether will like them or not