Jerry, you must've had some plan with that piece, it's bloody amazing, a terrific piece. Very Poulenc-ish in places and a curious smorgasbord of styles as you both start riffing off each other. Curiously, it sounds very European too in places.
Yes, I improvise. It's a necessary pre-composition starting point for me as much as it is a part of actual composition too. The way I see it is that improvising is working with raw materials and acting like a search tool, hunting out, and chasing down ideas, whilst actual composition is the imposition of order and will in an effort to refine and hone. Applying technique at the compositional stage for me, is all about teasing out any nascent material within an idea and a way of creating homogeneity in an extended piece.
Improvising can also take place mentally for me and stretches of musical phrase can be parsed in real time and as quickly discarded or improved upon. Improvising can also be done on the manuscript. I find it sometimes useful to work out long form in a graphic way on manuscript, plotting key moments and even rhythm, without the need for notes as such - a kind of route map. This is particularly useful when the sound-world of the piece has been worked out and has been mentally absorbed. One can quickly plot scenarios and gauge their efficacy in relation to the material and how one can proceed with it.
Finally, improvising with technique is essential to me too. A lot of people do not understand the connection between technique and the finished work. The underpinning provided and the creative challenge presented by self-imposed (self-designed) parameters, is what distinguishes a great piece from most imv. The limitations ironically freeing the creative spirit by challenging it to overcome are an essential driver and mechanism for writing music that is unified and inevitable in its expression. These limitations are of course continually re-assessed during progress and are flexible enough to be altered should an unexpected musical twist occur.
This all sounds very cold, but in reality it is not. One is ultimately always swayed by the pull of the music and that is the final arbiter.
Nope, just pure improv; I turned on the recorder and we played for about 30 minutes. I did however take the best of what we did and assembled them into little "vignettes" to give it at least a little bit of cohesion. I don't think of doing that as composition, but rather just a little bit of editing.
I know another composer, John McGinn, who also does what you described, where he works out ideas in notation, primarily rhythmic, but not putting any actual pitches in until later. I've never been able to work like that, but that's what makes composition so unique, each person has their own method to the madness. Improv also for me is about the raw, spontaneous musical impulse, unrefined, uncensored, without the critical mind intervening until composition begins. That's why it's so important to me. Wasn't it Stravinsky who said we shouldn't have contempt for the fingers, or something like that? I think he meant that sometimes the hands have an innate musical wisdom all their own and there's a certain almost child-like freedom in just moving around the keyboard (or whatever instrument you improvise on) and seeing where things go. All the accidents happen in improv, but the decisions happen in composition, or something like that..