The two guys in Matmos have adopted lots of different personae, but they've never been especially free-spirited—at least not on conceptual albums devoted to the sounds of surgery, songs from the Civil War, and "audio biographies" of luminaries like Ludwig Wittgenstein. Of course, none of those proved as leaden as their premises might suggest, but Matmos wouldn't be Matmos without an idea to mull. The principle behind Supreme Balloon is a sound focused solely on synthesizers—including weird old ones like the Omnichord and a "breath-controlled oscillator" called the E.V.I.—and the result plays something like a history lesson in all that is cosmic and confined in the electronic-music of old. The songs are generally jubilant, as signaled by the whirring synth giggles and quasi-Cuban bassline in "Rainbow Flag," but also slight in a way that suggests much of Supreme Balloon would have been a lot more fun to make than it is to listen to. That certainly applies to an ambient title track that goes nowhere beyond wiggly test-tones for 24 minutes—a long time to go nowhere, no matter the concept.