Jim Dickson, a key architect of the ’60s folk-rock sound and the original manager of the Byrds, died of unknown causes April 19 in Costa Mesa, Calif. He was 80.Born in Los Angeles, Dickson worked as a record producer in the early ’60s, cutting proto-folk-rock sides by singer-songwriter Hamilton Camp, progressive bluegrass units the Dillards and the Hillmen (which included future Byrds member Chris Hillman) and singer-songwriter David Crosby. He took up management of Hillman and Crosby’s fledgling new band, which was styling itself as an L.A. equivalent of the Beatles. Employing free studio time cadged by Dickson, then a staff producer at World Pacific Studios, the group cut early tracks as the Beefeaters and the Jet Set. In 1964, Dickson received an acetate of the unreleased Bob Dylan song “Mr. Tambourine Man” from the singer-songwriter’s publisher. His charges, a quintet now known as the Byrds, recorded it for Columbia Records (employing backup studio musicians), and it became the band’s breakthrough No. 1 single. Dickson and management partner Eddie Tickner handled the Byrds, who became the preeminent folk-rock band of the era, through a bitter split in June 1967. The pair subsequently worked with the Flying Burrito Brothers, a country-rock unit including Hillman, Byrds drummer Michael Clarke and latter-day Byrds member Gram Parsons. Dickson produced the group’s A&M albums “Burrito Deluxe,” “The Flying Burrito Brothers” and the live “Last of the Red Hot Burritos,” and is credited with helming some of Parsons’ post-Burritos solo recordings. In 1972, Dickson helped ex-Byrd Gene Clark re-record and remix his 1967 album “Gene Clark with the Gosdin Brothers.” Dickson later moved to Hawaii, where he became a competitive sailor.