Dolphin didn't build this empire, he bought it. The store and pressing plant had existed under different owners since at least 1919. In 1950 he started his record label RIH, for Recorded in Hollywood.he released sides by Errol Garner, Scat Man Crothers, the Roberta Martin Singers, Joe Houston and Illinois Jacquet. More here. Many of these were only sold at his record stores. (most of the label's catalog ultimately ended up in the hands of Decca.)
What Dolphin did that made him unique to the era was to hire white DJs to play black music on the radio. He hired Hunter Hancock and Dick Hugg to play his records and those of other black artists. In so doing he gets credit for popularizing R&B on the west coast and start the careers of numerous, jazz, rock and R&B artists. The store and by connection John Dolphin, were made famous by those broadcasts. Dick "Huggy Boy" Hugg is probably best remembered. He was a DJ on KRKD-AM. He was a white DJ and he broadcast a live rhythm and blues radio show from the front window of Dolphins of Hollywood. The program ran from Midnight to 4:00 AM. Huggy was on air at KRKD in that window from 1951–1955.
Hancock was on KFVD in 1943 playing race records even without Dolphin paying him. He'd previously been on KMAC in San Antonio. In most of his biographies it mentions KGFJ but not KRKD. This is because the station changed calls after 1955. Hancock had an afternoon program broadcast form the same window as Huggy. He started in 1952 and kept it up until he left for a gig at KCLA. He retired from radio in 1966 after outliving a payola scandal in the late 1950s.
Huggy later was on KALI, KRLA, KGFJ, KBLA, XPRS and was still broadcasting in his 70s in 2002 on KRTH. Dick Hugg died of cardiac arrest on August 30, 2006 at age of 78. In true rock n' roll fashion Dolphin was stabbed to death in 1958. by a song-writer Percey Ivy, whom he had cheated out of royalties. His widow continued to operate the record label into the 1960s.