Carl Fischer Music owns a gigantic 8-foot-tall tuba nicknamed "Big Carl." Big Carl is not a proper tuba, lacking pistons and valves, so perhaps it's more accurate to call this beast an overgrown bugle. In any case, Big Carl is enormous, and in this short video we see Derek Fenstermacher, principal tuba with the New Jersey Symphony Orchestra, give it a toot. He points out that the ultra-low, rumbling tones sound like "a jackhammer" or "a helicopter." Enjoy the sound of hugeness:

You can read more about Big Carl (including its oddly murky origins) from The New York Times.