''We've got old news,'' sing this Philly band on their third CD, We All Belong. That's no lie. Their giddy lo-fi rock addresses good weekends, bad trips, and love-ache hardly new topics and evokes the Beatles (or Beatles solo projects) when not generally conjuring '70s AM radio with spangly guitars, sleigh bells, and shout-along harmonies. But like pals My Morning Jacket, Dr. Dog blend ''classic rock'' elements into woozy, idiosyncratic songs all their own. Even when blue, they sound like the happiest band in indie rock.