As I understand it:
Paul C. Buff started a recording studio in the greater Los Angeles area in the early 60's, was involved in the recording of surf music, worked with Frank Zappa and at Art Laboe's Original Sound recording studio and developed Allison Research in CA.
He moved to Nashville and merged Allison Research with Valley People. Universal Audio has an interview with Doc Morgan which outlines some of the history.
http://www.uaudio.com/webzine/2008/april/index4.htmlNow PMI (of Joemeek, Studio Projects and Toft fame)owns Valley People and is looking to start releasing new products from the company.
The earlier products were more of what would now be called "character" units while the later generation products would have less of a "distinctive sound" and be more all around units. I currently have a mid-80s Valley people compressor which is a bit dark according to current standards but very musical. In the mid 80's I regularly used the Allison Research gates with large format analog tape. Don't know what I'd think of them now, but they worked fine then.
Hope this helps.
Galil