
From Downtown Music, 1971-1987: An Overview and Resource Guide, by Peter Cherches:
Jazz critic Gary Giddins denies that there is any style of music that one could call “loft jazz,” stating that “Loft jazz is any jazz played in a loft.” For practical purposes, however, one can identify certain elements that characterize a great deal of the music performed at the lofts in the ‘seventies. It was clearly music that fell outside the jazz mainstream, carrying forward the legacy of ‘sixties free jazz but informed by other strains. The musicians continued to eschew the popular-song harmonic foundation of bebop while often foregrounding the blues elements that were somewhat more subliminal in much of free jazz. Rhythmically, some of the music began to incorporate influences of funk, African and Afro-Caribbean music, alongside the more abstract free-jazz foundation.
Sam Rivers and his wife Beatrice ran THE NYC loft jazz hot spot in the ’70s at his Studio Rivbea on Bond Street. Hundreds of musicians hung and/or played at the lofts including not-so-obvious youngsters Joe Bowie of Defunkt, John Zorn and James Chance, “I did have a small trio or quartet that played in a few of those lofts. But, uh, I didn’t really see it going anywhere. I could just tell the jazz scene was not going to accept me.” Maybe it was the pompadour.

There’s a five LP set – Wildflowers: The New York Loft Jazz Sessions that collects one week’s worth of music from Sam River’s Studio Rivbea from nearly 100 musicians including; Ken McIntyre, Sunny Murray, David Ware, David Murray, Dave Burrell, Julius Hemphill, Anthony Braxton, Roscoe Mitchell, and Jimmy Lyons. Originally released on Douglas records in 1976 and re-released as a CD box set by Knitting Factory records.
I have Volume 1 on the way. In the mean time, check out this Sam Rivers ’74 release for some very cool and out-there free jazz big band funk from the height of the loft jazz era:

Sam Rivers
Crystals