Following the surprise release of 2016's Abandoned Mansion, free-wheeling Philadelphians Dr. Dog forge ahead with 2018's Critical Equation, the band's similarly reflective and pleasingly streamlined tenth effort. Having bid farewell to Anti-, their label since 2010, the quintet make their roster debut on Nashville's Thirty Tigers imprint, which feels like a suitable home, given the vintage country rock leanings they've flashed throughout their career. In a way, Critical Equation is a continuation of what they've been doing since the beginning, replete with the lightly psychedelic flourishes native to their sound, yet coming across as tighter and perhaps more focused than they've been in years. It's a subtle shift, but the core narrative of these ten songs is one of confident forward movement built on an already sturdy foundation. An enigmatic darkness runs through the album's front half, from the pensive opener "Listening In" to the sleekly defiant "Go Out Fighting" and the sprightly "Virginia Please." As with much of Dr. Dog's catalog, the melodies are strangely catchy without necessarily being straightforward. Placed midway through the set, the title cut acts as a rich tonal centerpiece with delicately built verses and a rich pay-off of a chorus that flashes the band's harmonic chops. "True Love," another mid-album highlight, is a wonderfully breezy rocker with a relaxed feel that manages to blend old-time rock, country-pop, and gentle sprinklings of psychedelia which help to set up the excellent "Heart Killer," easily the hookiest track of the bunch. Rather than breaking the mold, Dr. Dog instead double down on their strengths to make Critical Equation a surprisingly vital outing.