JBL Control series One Book shelf speaker Have enviable JBL sound anywhere you want it: a bookshelf, desk, in the kitchen, a home theater, up on a wall, even as part of a multiple-room home music system. The rugged, compact enclosures have a 4-inch woofer and a 1/2-inch titanium laminate tweeter for a smooth frequency response of 50Hz to 20kHz. They’re magnetically shielded, too. Put them anywhere.