Let's be honest: Although Timbaland has to be in the conversation when discussing the greatest pop music minds of our generation, the big man is no frontman.

Let's be honest: Although Timbaland has to be in the conversation when discussing the greatest pop music minds of our generation, the big man is no frontman.

Tim Mosley's claim to fame is his pioneering work as a producer. His string of smash singles for the likes of Missy Elliott, Aaliyah, Justin Timberlake and Nelly Furtado were as mind-bendingly inventive as they were ass-shakingly popular. His under-the-radar work with acts like Bubba Sparxxx was just as brilliant.

Mosley has always peeked out from behind his genre-shaping beats to rap a few words, which seems like just the right amount of Tim on the track. Think of his turn on Aaliyah's "Are You That Somebody." He makes a killer wingman.

Yet around the time he made friends with Timberlake, he started creeping closer and closer to the spotlight with increasingly awkward results. His ascent paved the way for tone-deaf auteurs like Kid Cudi, whose success in turn perpetuated a pop landscape where Tim's ill-advised star turns still seem kosher.

Still, Timbaland is smart enough to continue letting his solo albums be showcases for his production skills - see 2007's Shock Value, which yielded a couple club classics, and 2009's Shock Value II, which, not so much.

Ever since hitting it big with the OneRepublic power ballad "Apologize," Tim has been lazy and erratic; last year he misfired egregiously with Chris Cornell's maligned solo album and did dreadful work with Miley Cyrus and Nickelback's Chad Kroeger on Shock Value II.

So his show Saturday at the Newport presents plenty of questions, hopefully with answers like "Guest stars!" and "Greatest hits!" (If J.T. beatboxed with Brother Ali in Wyoming, surely he could show up here.)

The night before, The Summit will host acts with much lower profiles who've also spent their careers pushing hip-hop forward, usually in the instrumental realm.

Headliner Prefuse 73 (aka Guillermo Scott Herren) became one of music's leading lights a decade ago by splicing rappers' verses into bits, rendering them as just another instrument in his "glitch-hop" soundscapes.

He sealed his reputation with chill 2001 debut Vocal Studies + Uprock Narratives and 2003's slightly more aggressive follow-up One Word Extinguisher, not to mention the exotic jams he cooked up in Barcelona under the name Savath y Savalas.

Herren hasn't been as prominent in an underground infatuated by newer crazes like dubstep. I thought his productivity had slowed, but it turns out the hype is all that's run dry. His fifth LP, Everything She Touched Turned Ampexian, dropped last April. It's less stimulating than his earlier works, but if his live show still features multiple live drummers, it'll be a trip.

Joining Herren Friday will be The Gaslamp Killer, a rising Los Angeles producer who rolls with fellow hip-hop futurist Flying Lotus. Voices Voices will perform first.