The Leslie speaker spins its sound, and Hammond tried to block it
Donald Leslie bought a Hammond organ in 1937 and hated how flat it sounded at home. His fix was a speaker cabinet with spinning parts that mimicked the scattered voice of a pipe organ. Laurens Hammond refused to sell it, even redesigning his organs to shut it out. Leslie sold it anyway.
Leslie was a radio repair engineer at a Los Angeles department store that sold Hammonds. The instrument that had impressed him in a big showroom sounded dull in his living room. Pipe organs, he reasoned, sound rich partly because each pipe sits in a different place, so he tried moving the speaker. After testing many combinations, he settled on splitting the signal between a rotating drum for bass and a rotating horn for treble.
Hammond was unimpressed by an outsider improving his design and changed the organ's connection to make it Leslie-proof; Leslie simply worked around it. From 1941 he built the cabinets under names such as Vibratone and Hollywood Speakers, answered Hammond's slogan with his own, Pipe Voice of the Electric Organ, and eventually held nearly 50 patents. He made them fit Wurlitzer, Conn and Baldwin organs too, and admitted he never liked Hammonds. Radio exposure and jazz organists made the sound famous.
Inside, an amplifier feeds a crossover that splits bass from treble. Players flip between two speeds, a slow chorale and a fast tremolo, often mid-phrase, and the swoop of the rotors speeding up or slowing down is part of the appeal. The horn always turns a little faster than the drum. The best-known model, the 122, stands 41 inches high with a 40 watt tube amplifier; players later prized the growl of those tubes when overdriven, which is why the later solid-state Pro Line cabinets, though louder and sturdier, are less admired.
Ownership wandered: CBS bought the company in 1965, Hammond finally acquired it in 1980, and Suzuki has made Leslies since 1992. Meanwhile boxes such as the Uni-Vibe have tried to fake the effect electronically.
Source: Leslie speaker
