In 2013, over a quarter century removed from his first album, Joe Satriani uses his solo albums as a way to stretch himself, both to flaunt his skills and perhaps to move him into areas where he's not quite comfortable.

Unstoppable Momentum, his first album since 2010's boogie- and prog-heavy Black Swans & Wormhole Wizards, finds the guitarist occasionally indulging himself in a bit of swing, letting him ride an elastic beat ("Three Sheets to the Wind" has a supremely delicate touch), and he also digs into a bit of a nasty ZZ Top groove on "Jumpin' In," a boogie he turns inside-out on its immediate successor "Jumpin' Out." This is a pretty good indication that this is the work of a virtuoso who enjoys playing with his surroundings, tweaking tempos and arrangements to coax out unexpected wrinkles.

Compared to Black Swans, this is livelier and fuller, containing a greater variety of textures, rhythms, and attacks, spending not quite so much time with head-down, barrel-headed boogie and rather suggesting jazz, blues, even soul.

Satriani often seems a little too restless for his confines -- he seems to enjoy when the tempo slows, so he can get a little lyrical -- but part of the appeal of Unstoppable Momentum is how Satch decides he should abandon his comfort zone, at least in part.

He still adheres too strongly to the heavily phased instrumentals that make him feel stuck in a past before MTV, but he'll also indulge in a bit of swing, rhythm, and momentum that not only give Unstoppable Momentum character, but suggest there's an audience outside of guitar fanatics for this densely layered instrumental music.