GLOSSARY - iReal Pro

[shin1ro]

A pianist (at least I would do it this way) would often voice a C7alt chord with the 3rd-7th tritone in the left hand (E and Bb) and the #9 and b13 in the right (D# and Ab), often with the root in the middle; it would look like E and Bb in the left hand and an Ab triad with the Eb on top in the right hand. The "formula" is: the dominant 7th tritone with the b13 triad on top.

Keith,
Thanks, you explain very well how C7alt is performed by human player in reality.

Gabz recipe says C7alt = 1 3 b5 7
(that is C E Gb Bb)

While in my observations of C7alt by 8-bar tests,
- piano, strings in Jazz Long Notes style
- guitar in Latin Brazil Bossa Acoustic style

iRP player's C7alt output notes vary frequently (not every time)
#1 C E Gb Bb Db (1 3 b5 b7 b9)
#2 C E G# Bb Db (1 3 #5 b7 b9)
#3 C E Gb Bb D# (1 3 b5 b7 #9)
#4 C E G# Bb D# (1 3 #5 b7 #9)
In Bossa guitar, root C is always omitted.
(actually #2 is not found on the piano)

I think it would be better the recipe to be updated,
reflecting the fact of what iRP player plays at C7alt.