The caveat with mentioning the 30 years of history John McEntire and Sam Prekop shared before making Sons Of is that the album doesn’t exactly sound like anything they’ve done before. McEntire is the drummer of the adventurous, anything-but-rock band Tortoise and the Prekop-fronted Sea and Cake; Prekop is a singer-songwriter who rebutted the harshness of ’90s indie rock with music influenced by lounge jazz and bossa nova. Sons Of, by contrast, is made up of four lengthy synth improvisations combining early house, indie pop, and the spacey, ruminative side of IDM. The connective tissue is in the approach, which is somehow adventurous but gentle, experimental but restrained. And while everything here has narrative momentum, their shared language is thick enough that they sound better the longer they go (the sunglasses-indoors sci-fi of “Ascending by Night” and the 24-minute “A Yellow Robe”).