William Paul Mitchell got cracking with his Large Professor alias as part of early-’90s hip-hop trio Main Source, and went on to construct beats for Nas, Kool G Rap, Cormega, A Tribe Called Quest, plus dozens more. Like fellow ’90s greats Masta Ace, Pete Rock, or Gang Starr, Mitchell’s soul-sampling boom-bap blueprint has been modernized but remains largely unchanged. That’s a plus on infectious party tracks like “Pump Ya Fist” and “Hardcore Hip-Hop,” which rumble and rattle with funky loops and starchy-crisp beats. Jeru Tha Damaja, Styles P, AZ, and Big Noyd add some memorable bars, but Mitchell is musically and lyrically front-and-center throughout. With a title referencing his roots, Main Source is proof that Mitchell is still a pro.