A five-man rock band without instruments, the House Jacks' "no-holds barred" a cappella style obliterates traditional preconceptions about the limits of the human voice. Bert Bacco, Deke Sharon, Garth Kravits, Wes Carroll, and Austin Willacy run the gamut from tender love ballads to mile-a-minute funk, complete with mind-blowing vocal percussion and riffs that you would swear tore straight out of a whammy-bar guitar. Taking their name from Heavy Equipment section of the Yellow Pages (a house jack is what you use to move a residence), the Jax originally got to know each other on the collegiate a cappella circuit of the late 1980s. The group has completed several successful world tours, gained thousands of devoted fans, and recorded four albums including last year's hot release, Unbroken.