I ran across this today:
The first subwoofer was developed during the 1970s by Ken Kreisel, current president of Miller & Kreisel Sound Corporation in Los Angeles. Kreisel's business partner, Jonas Miller, owned a high-end audio store in Los Angeles, and customers of some of the highest quality electrostatic speakers complained about a reduction of bass response in the electrostatics, compared to conventional loudspeakers; Kreisel's solution was to design a powered loudspeaker that would reproduce only those frequencies that were too low for the electrostatic speakers to convey and thereby fill in the missing sonic information.. Infinity's full range electrostatic speaker system of about the same time also used a subwoofer to cover the lower frequency range the electrostatic arrays did not handle adequately.
The first use of a subwoofer in a recording session was for mixing the Steely Dan album Pretzel Logic when recording engineer Roger Nichols arranged for Kreisel to bring a prototype of his subwoofer to Village Recorders. Further design modifications were made by Kreisel over the next ten years (and continuing to the present day), and in the 1970s and 1980s by engineer John P. D'Arcy; record producer Daniel Levitin served as a consultant and "golden ears" for the design of the crossover network (used to partition the frequency spectrum so that the subwoofer would not attempt to reproduce frequencies too high for its effective range, and so that the main speakers would not need to handle frequencies too low for their effective range).