There are few instrumental arrangements as loaded as the saxophone quartet. A piano trio might be classic jazz, but it's been so many other things that it's easily opened. But the sax quartet - Duke Ellington wrote for them, ROVA and WSQ made them into variable bands, it means something.

And while the flexibility of the sax has made it a key instrument in recent waves of minimalist improv (see John Butcher's remarkable The Geometry of Sound (Emanem, 2007) for some remarkable pushing of new technique), the sax quartet has, perhaps, been too hot a thing to touch. (James Fei's group worked in the vocabulary but was more formalized than the 41 minutes of open improvisation here.) While the saxophone affords percussive, woody, metallic and breathy voices, it is still a monophonic instrument (forced overtones still being tied to the note played). So while Baron and Guionnet (on altos) and Denzler and Rives (on soprano) take full advantage of their horns, some surprising things emerge in the course of their playing, chief among them being harmony. It might not be the harmony of a triad with an added seventh, but the most electric moments of this disc occur not when there's a smear of sound and interjections, but when there are four distinctive voices contributing to a single idea. At those moments the quartet truly forges something new.