Some of this discussion on swing can get very technical. This is because I'm at a point now where I'm becoming conscious of what it takes to play jazz at a pro level.
This is a continuation of the journey to improve articulation and swing and part 3 of the thought process.
The more I think about the "swung eighth" position that I illustrated rhythmically in part 1, the more ideas are popping into my head.
How exactly do the masters line up their eighth notes so it fits that position of landing the offbeat on the 3 of the triplet (what I've been calling the sweet spot)? I discussed the Erskine vocalized "Uh" as the subdivision mechanism but's really hard to apply at a fast tempo, especially on the first note.
So on to further analysis. Here in this recording, I was playing with my teacher on two pianos. I just extracted his portion of the solo so I can analyze his groove. Very relaxed feel here. This is a very simple version of ATTYA so it's easy to understand. Rhythm section is iRealBook from an Iphone.
I know that I'm right that of the offbeat eighth lands on the 3 of a triplet (a triplet representing two eighths), it will swing even if the eighths are played straight. That was already proven by the sequenced recordings in part 2. But now here is a real player playing straight eighths and it swings.
I think I figured it out. He's playing the first eighth as a dotted eighth (so slightly longer) and then the rest of the eighths are played straight. That's how you make straight eighths swing. I was playing with one of the phrases over and over and I can feel the difference in each note length.
That's my theory at the moment. Listen to the recording. I sense that the first eighth, especially starting from a rest is longer. A dotted eighth would be an exact match rhythmically.
This is a mind boggling discovery if true because it give a precise way of getting a groove. So the rest is just how even you can play your eighths (like Classical).