As promised in a previous post, here is a great example of how to escape from the sometimes monotonous head/solo/head format. In this example of the song "Just You, Just Me", Chuck Redd (the vibes player) sets the pace by introducing a new melody halfway through the song. This is not something that you can do lightly, and there are a number of instructive things that Chuck did to make sure that this unusual technique would work. The following are three of these things extrapolated into general principles for making weird thing work.
1. Broadcast your intentions ahead of time
Chuck introduces the new melody ("Evidence" by Thelonious Monk) a chorus ahead of time by quoting it on the bridge at 3:26. This gives the musicians in the band a heads-up that something funky could be going on (although I still totally bungled the transition to the new melody). Of course there is nothing wrong with actually talking about an idea before you begin the song, but that is only if you think of it ahead of time and doing this can also take some of the fun element of surprise out of the music.
This is certainly not the first time I have brought up the importance of listening, but nowhere is it more obviously important than when something outside of the box is going on. If you are just playing on auto-pilot and you aren't engaged in what is going on in the music around you, you will totally miss any subtle hints that something strange is happening and will most likely make a mess of things. For example, notice how quickly everyone in the band picked up on the new melody. Even though I was shaky for a second, because I was listening I could find my way back by the second A section.
Another great example of listening is how Chuck picks up on the phrase from Nicki's solo (5:05) and turns it into a shout chorus!
3. Know what works and what doesn't
Chuck knew that "Evidence" fit well over "Just You, Just Me", and that it could easily be super-imposed for that reason. Knowing when this sort of thing will work and on what songs is a key component to pulling it off. Essentially, you can't move between melodies successfully in this fashion without a great deal of knowledge and experience.