Josef Anton Hofmann (July 22, 1924 – November 12, 2010)^[1][2] was a London-born American audio engineer and speaker-system designer. He is known for Hofmann's Iron Law, and was a son of pianist Josef Hofmann.^[2]

Hofmann was born in London in 1924, grew up in Philadelphia and Los Angeles, and graduated from Fairfax High School of Los Angeles in 1942.^[3] He studied at the California Institute of Technology and the University of Pennsylvania and worked on the Manhattan Project as a member of the United States Army.^[3] After World War II, Hofmann attended Harvard University, ultimately earning a doctorate there in 1953.^[3] Hofmann went on to have a 35-year career as an audio engineer, including work at Acoustic Research, KLH, and Advent Corporation, all in Cambridge, Massachusetts.^[3] Hofmann was the "H" of KLH, which he co-founded with Henry Kloss and Malcolm S. Low.^[4]

Hofmann and his wife, who were married in 1951, had three children. Hofmann died from lung cancer in 2010 in Waltham, Massachusetts.^[3]

Hofmann theorized that when woofers are mounted in speaker enclosures, the designer would have to accept that there are three trade-offs. Hofmann argued that the designer had "...three parameters that cannot all be had at the same time. They are low-bass reproduction, small (enclosure) size, and high (output) sensitivity." Hofmann stated that designers could pick two of these three parameters, but in doing so, it would compromise the third parameter.^[5]

For example, a designer who wants good, deep low-frequency sound and high sensitivity can obtain these goals, but they will have to use a large speaker enclosure. Similarly, if a designer is forced by space constraints to use a very small cabinet, and they aim to get good, deep low-frequency sound, the sensitivity will be compromised (i.e., a small cabinet with deep bass would need a very powerful amplifier).