Dr. Dre’s highly-anticipated album, “Detox,” has yet to hit store shelves, but the rap mogul has already claimed the top spot among hip-hop earners, according to Forbes magazine’s annual ranking.

Dre’s rise to the front of the pack is almost entirely due to Beats by Dre, which dominates more than half of the premium ($100 and up) headphone market. According to the magazine’s Sept. 24 issue, Beats by Dre accounted for $100 million of Dre’s $110 million in pretax earnings in 2011.

The rapper/producer launched the careers of stars such as Snoop Dogg and Eminem, and entered the headphone business at the urging of Interscope Records’ Jimmy Iovine, one of the partners who joined Dre in launching the Beats by Dre venture in 2008. When handset maker HTC paid $300 million last year for a 51 percent stake in Beats, the earnings helped catapult Dre past hip-hop colleagues such as Diddy, Jay-Z, Kanye West and Lil Wayne, who rounded out Forbes’ top five.

Like Dre, most of Diddy’s income was made outside the studio. According to the Forbes report, his $45 million stemmed mostly from sales of Diageo’s Cîroc vodka. For Jay-Z, more than half of his $38 million came from ownership in the Brooklyn Nets, cosmetics company Carol’s Daughter and other ventures.

Kanye came in fourth with $35 million, boosted by album sales and tours for his “Watch the Throne” album with Jay-Z. Weezy drew in a reported $27 million from sales of his smash hit album, “Tha Carter IV,” along with an endorsement deal with Mountain Dew and profits from Trukfit, his clothing line.

Other entertainers appearing at the top of the list include: Drake at No. 6, with $20.5 million, and Cash Money co-founder Bryan “Birdman” Williams at No. 7 with $20 million. Nicki Minaj was next, representing the female MCs with $15.5 million, while Eminem came in ninth, fueled by his back catalog, shows and a successful lawsuit against Universal Music Group involving royalties from digital sales of his music.

Down South rapper Ludacris rounds out the top 10 with earnings of $12 million, garnered from his headphone company Soul, roles in movies such as “Fast Five,” profits from Conjure cognac and his voiceover work for Radio Shack.