The Punch Brothers play what I call “chambergrass,” with detailed songs as influenced by Bartok as by the Beach Boys or Bill Monroe. Chris Thile and four friends started the band after Nickel Creek announced their dissolution; this is their fourth album, and it’s a doozy. Of all things, love and cellphones are its warp and woof. “Familiarity,” a ten-minute suite, presents the cell in its role as purveyor of songs you only pretend to love because you love the friends playing them. In “I Blew It Off,” the girl’s “trouble vibrates the table, interrupts my reverie.” In “My Oh My,” Thile sings, “Something beautiful’s gonna come/Out from underneath our thumbs/To let freedom vibrate not ring.” The stunner is “Magnet,” a number about a passionate encounter that also wonders, “What’s the center between two centers of attention?” Interspersed are two songs harking back to pre-cellphone days: an original, “Julep,” sung from the point of view of a deceased but happy old man, and the traditional “Boll Weevil.” Both of those are followed by the album’s two instrumentals, Debussy’s “Passepied” and a Scriabin prelude, both stunningly arranged and affectionately played with bluegrass instruments. Phosphorescent is a record to live with and wonder at. Sound is close-up and accurate.