Tribute albums are usually pretty simple affairs. Sometimes, one artist covers a slate of hits by one or more of his influences. Other times, a group of performers celebrate a beloved hero or a classic album. Occasionally, an elder statesman recruits friends and followers to rework his own classics. But 3 x 4, the new collaborative album from a quartet of L.A. Paisley Underground OGs — The Bangles, Dream Syndicate, Rain Parade and The Three O’Clock — somehow manages to be none of these and all of them at the same time. As its mathematical title suggests, the 12-song disc has all the bands covering each other in a round-robin celebration of their shared past. Not surprisingly, The Bangles — the short-lived ’80s scene’s most successful alumni — are likely to attract the most attention with their jangly, harmony-rich versions of Dream Syndicate’s That’s What You Always Say, Rain Parade’s Talking In My Sleep and The Three O’Clock’s Jet Fighter, while their own tunes Getting Out Of Hand, Hero Takes a Fall and Real World provide some of the disc’s more instantly identifiable moments. But don’t skip Rain Parade’s epic slow-burn stroll through Dream Syndicate’s When You Smile, their Eastern-spiced rendition of The Three O’Clock’s As Real As Real, or Dream Syndicate’s serrated sprint through The Three O’Clock’s garage-rock nugget She Turns To Flowers. And be glad nobody was forced to cover Walk Like An Egyptian.