Selecting the right effects stompbox will keep your sound on sure footing Many legendary rock moments—Jimi Hendrix wailing through an Octavia on “Purple Haze,” or the Edge’s lush delay on U2’s “Where the Streets Have No Name,” for example—were crafted using carefully chosen effects pedals. Guitarists of all genres use these small, specialized signal processors to tweak their instruments’ sounds in wildly creative ways. And they’re...