So I've been listening to Phish a lot lately, including some of their live albums, and they jam a lot. Yet the structure of the jam feels kind of orchestrated as they all switch progressions, dynamics and finish off the jam at the same time. How do they keep track of those changes?

Also, from my understanding, for some jazz songs, you play the main melody, then everyone solos over a certain number of choruses, then they end the song. In a case like that, how does everyone keep track of where they are in the chorus? Do they just count the measures?
Yeah, you answered it yourself! You got to count measures. And what Phish is doing is also realated to this. After X measures switch prog, then after Y measures do this and end it.
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There's really a few different levels, when you refer to 'jamming'. I mean, if you're playing a song and have decided to extend part of it, then the progression wont spontaneously change unless you've given a nod or something. But when it's just a loose jam, it can go on for 20 minutes without having any real structure. Co-ordination as a band I suppose just comes from watching each other, everyone has their own way of communicating.

Jazz is, of course, not in the same rulebook as rock or metal, so like the above message says the length of each part of it is already known, its just the way its played that is free.
Last edited by voodoochild23 at Jun 25, 2009,
All of these answers are good.

But also keep in mind that the caliber of the musician, combined with the amount of time they have been playing together and what not has a lot to do with this as well.

I saw a jazz combo play a few months ago. These guys have been playing together (the same guys) for 41 years. On stage, they are pretty much telepathic. Once you play with a group of people long enough you get to a point where you can almost predict what the other members are going to do. It is all part of being a tight little group.
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Ah, cool guys. Thanks.

When jams go on for 20+ minutes, isn't it a bit of a brain workout to both count measures and think about what you are improvising as well? After doing a bit of searching, I found that there are also musical signals. Like if the guitarist plays a certain melody over the progression, it means that the progression will change at the end of the next measure, or something like that. That seems a lot easier than counting large numbers of measures
A good drummer will set you up so you don't need to pay as much attention when you count.

Counting is also easier if you know the form of the song. I'll take Satin Doll as an example (http://www.youtube.com/watch?v=SDDCzb3dv_Y): The form is AABA.

It has the 8 bar "A" section. It is repeated for the next 8 bars. Then it goes to the 8 bar "B" section, and repeats back to the 8 bar "A" section. AABA. After that the musicians solo over the chords of the song, still keeping to the AABA format.

Keep the form of it in your head. The rhythm section will make the same changes and give ques as to where the song is. A drummer can do things likes rolls, fills, or a big crash to signify the bridge, the top, or a new phrase. The guitar, bass and piano will play the changes. You can use those to know where you are (afterall the changes in the B section are different than the A section).

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Yeah a lot of their songs go through intricate composed sections (many up to 15+ min) followed by vamps at the end where they jam. They do use signals at times during jams, and all have really good ears & have worked on improvising together a whole lot. Here's a lesson given by their guitarist that goes over some of the improvisation exercises they would do which will help shed some light http://allegedartist.wordpress.com/2009/06/16/random-find-3-trey-anastasio-guitar-clinic/ There's a link on that site that goes over some of Trey's playing style as well