mostly trying to explain to the novices...
The formula for Jimmy Stewart has changed so much over the last 3 years. Giving a standard definition, doesn't necessarily do it justice.
The jamming is not always linear. Some bands touch on the concept of non-linearity. Some do it with much greater depth and style than others. You've heard bands jam where someone starts up a riff, and everyone starts playing said riff. Simple stuff. Someone starts playing the outlying chords, somebody starts soloing. Voila! You're a jamband.
What UM does on a consistent basis, and with fluidity (which is where people get confused), is create a longer riff, that spans an entire measure, or longer. By doing this, you give the rest of the band more room to work with and create. And create they do. When no longer confined with a quick repeating riff to play off of, the other 5 members are able to create their own textures that build off the original riff. And, with each completion of the section, they go back to the top to repeat it (hence the non-linearity). Allowing for futher coloration and characterizing of that little piece of music. Then take it where it may. Sometimes modulating it through different keys or changing the tempo/dynamics of it. After they're done toying with said section, they just move along to the next section by holding out a chord (you'll see jake do this a lot. Like he's wiping off the table).
For the most part a Stewart is designed to have at least 2 separate sections. This is where it really starts to get fun. And where UM really distances themselves from the pack. The Bounceback jam. After leaving the first section (as discussed above) they'll move along to wherever they go next (usually playing off the last outlying chord of the previous section). Another sections is started, built upon, and repeated a few times. Now here's where the pure beauty of it all comes in. When they get to the end of this 2nd section, instead of going back to the top, you'll see Jake lean backwards. And instead of repeating section B again, they're now back at A. Playing it even tigheter and with more flair than they did their previous attempt 3 minutes before. Then another few runs through that, Jake leans back, and then they're back in section B, playing it, again, better than they had before. So what they do, is build 2 unique sections of music together, seperately.
Instant composition. That's the difference. They don't just improvise, they create unique pieces of music night in and night out.
And some of you wonder why UM fans can get frustrated when people say they don't know how to jam. Their methods are refined to a point well beyond anything most of us has heard.
the line between Stewart and JO has slowly erased (by our footsteps, by our footsteps...) or at the very least become very cloudy (you know like when you erase pencil with those shitty smooth erasers? like that). JO is more straightforward, no bounceback involved. Usually less signals involved.
Pony basslines: You've heard them. You know them. He's always trying to work new ones into jams as possible songwriting fodder. So if you hear him repeat something from a previous show, don't feel like you're getting slighted because he's not up there improvising as much as the others. They aren't chosen at random. And plus some of them are just such tight grooves that they're worth playing multiple times, just to see how different versions unfold.
written out stewarts: from time to time, the band will write out sets of chord changes, as well, a general idea of how they'll want to play said section (drum n' bass, ambient, uptempo...) Or on the even rarer occasion Jake might bring something to the table, maybe a section that he's been working on. Written out stewarts, you'll hear the band make changes during which there's no way any band could just decide to change sections like that. It's not *pure* improv. It's kind of like an outline for improv. Mostly for creativity and melody making, not soloing. To possibly take that section and turn it into a song in the future.
Bayliss vox -
all fans of improv love the feeling of living in the moment of the music. From time to time, BB will take a jam even farther and start spouting out lyrics (sometimes improv, others from his apparent 'lyric notebook', like passages he's working on putting into songs). When the band gets locked in, sometimes, he's just feeling it, and you really do truly get a full taste of instant music writing. 9/4/03 DBK that gave rise to Ocean Billy is your definitive source on this.
Stewarts > songs:
#5, Wife Soup, In the Kitchen, Ocean Billy, Bridgeless, Robot World.
The band goes back to listen to their jams/stewarts to see if there's any good material (of which there is plenty, but they're picky) to use as a section for a new song.
Signals: there are lots
step forward, back. (modulate up/down a minor third, I think)
neck of guitar up, down (modulate up/down a whole step).
wipe off (clean the slate)
lean back (my personal favorite, go to previous section).
hand over the head (return to the top of a jam, head of the song)
hand signals to denote chord/key to change to.
rub nipple (milk it. keep playing this section)
fist at eye level (hold this groove)
this list is by no means all inclusive...