Some bands carry an intrinsic novelty - a freshness, a thrilling sense of invention - largely because there are very few similar bands in the South Sound. Arpeggiator has this advantage, as one of the few Tacoma-born math-rock bands around. That Arpeggiator does math-rock so well is certainly a bonus. I realize that math-rock, to some, is a fairly nebulous term. Here's what Arpeggiator is: a two-piece drum-and-guitar combo that constructs diabolically twisting instrumental pieces that are furiously propulsive while constantly sounding precarious, like the song may disintegrate at any moment. There's something quite visceral about never being sure where Arpeggiator will go next. One feels at mercy to the music, which is a fine change of pace around here. Arpeggiator wants to show you what they can do.

[Bob's Java Jive, with Umber Sleeping, Blanco Bronco, 9 p.m., $3, 2102 S. Tacoma Way, Tacoma, 253.475.9843]