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Rudolph Van Gelder (November 2, 1924 - August 25, 2016) was an American recording engineer who specialized in jazz. Regarded as the most important recording engineer of jazz by some observers, Van Gelder recorded several thousand jazz sessions, including many recognized as classics, in a career which spanned more than half a century. Van Gelder recorded many of the great names in the genre, including John Coltrane, Miles Davis, Thelonious Monk, Sonny Rollins, Art Blakey, Joe Henderson, Freddie Hubbard, Wayne Shorter, and Horace Silver, among many others. He worked with many record companies but was most closely associated with Blue Note Records.

Van Gelder was born in Jersey City, New Jersey. His parents, Louis Van Gelder and the former Sarah Cohen, ran a women's clothing store in Passaic. His interest in microphones and electronics can be traced to a youthful enthusiasm for amateur radio. A longtime jazz fan (his uncle, for whom Rudy was named, had been the drummer for Ted Lewis's band in the mid-1930s), Van Gelder took lessons on the trumpet. Van Gelder trained as an optometrist at the Pennsylvania College of Optometry, in Philadelphia, because he did not think he could earn a living as a recording engineer. From 1943, after graduating, Van Gelder had an optometry practice in Teaneck, New Jersey, and recorded local musicians in the evenings who wanted 78-rpm recordings of their work. He became a full-time recording engineer in 1959. From 1946, Van Gelder recorded in his parents' house in Hackensack, New Jersey, in which a control room was built adjacent to the living room, which served as the musicians' performing area. The dry acoustics of this working space were partly responsible for Van Gelder's inimitable recording aesthetic.  "When I first started, I was interested in improving the quality of the playback equipment I had," Van Gelder commented in 2005; "I never was really happy with what I heard. I always assumed the records made by the big companies sounded better than what I could reproduce. So that's how I got interested in the process. I acquired everything I could to play back audio: speakers, turntables, amplifiers". One of Van Gelder's friends, the baritone saxophonist Gil Melle, introduced him to Alfred Lion, a producer for Blue Note Records, in 1953.  Within a few years Van Gelder was in demand by many other independent labels based around New York City, such as Prestige Records. Bob Weinstock, owner of Prestige, recalled in 1999, "Rudy was very much an asset. His rates were fair and he didn't waste time. When you arrived at his studio he was prepared. His equipment was always ahead of its time and he was a genius when it came to recording". According to a JazzTimes article in August 2016, "jazz lore has formed the brands into a yin and yang of sorts: The Blue Note albums involved more original music, with rehearsal and the stringent, consistent oversight of Lion; Weinstock was more nonchalant, organizing what were essentially blowing sessions for some of the best musicians in jazz history". Van Gelder said in 2012, "Alfred was rigid about how he wanted Blue Note records to sound. But Bob Weinstock of Prestige was more easygoing, so I'd experiment on his dates and use what I learned on the Blue Note sessions". He also worked for Savoy Records in this period, among others. "To accommodate everyone, I assigned different days of the week to different labels".  In the 1950s Van Gelder also performed engineering and mastering for the classical label Vox Records. Thelonious Monk composed and recorded a tribute to Van Gelder entitled "Hackensack".
Rudy Van Gelder