Kyle Hollingsworth just turned 50, and with that milestone comes 50 , his fourth solo studio album. Listening to the sonic scope of this release, it’s pretty clear that when the keyboardist isn’t touring with String Cheese Incident or brewing a new beer (like Relix and SweetWater Brewing’s Ground Score IPA) he’s back behind the ivories writing even more music. 50 serves up 12 tunes, varied in style, but thematically leaning toward the optimistic, which is indicative of Hollingsworth’s countless feel-good contributions to the SCI catalog. The album opens with the space-age intro track “Onset,” and transitions into the rocking, synth heavy “Wyatt Earp’s Tale.” Hollingsworth doesn’t sing until “Let Me In,” where his keys take the backseat to a funky guitar riff, and he shares the microphone with singer Tanya Shylock. Shylock is the first of many guests on 50 , including Jen Hartswick, Kim Dawson, Andy Hall, DJ Logic and SCI’s Jason Haan. Hollingsworth enlisted his live band (guitarist Dan Schwindt, drummer Brian McCray and bassist Paul McDaniel) to play in the studio, and as the album goes on, the keyboardist dips down several creative avenues, including the academic on the rollicking sing-along “Prime”—written about a real-life equation so perplexing it has been known to drive people into fits of insanity. He also segues into the emotional on “Finding Our Way.” The stripped-down ballad provides the first introspective moment of the album, and tells a tale of Westward exploration that recalls Hollingsworth’s own origin story, relocating from Baltimore to Colorado and eventually becoming “a father with two daughters.” It’s quite a contrast to the groovy standout “Come  On,” which features a dueling keyboard vs. turntable format that is sure to soar the next time Hollingsworth and DJ Logic share the same stage. By the LP’s final “Offset,” 50 has truly run the genre gamut. And while Hollingsworth will always have a key role in the collective String Cheese Incident sound, hearing him take centerstage on this LP is a delight.