The urbane, pop-friendly Nashville Sound production style emerged in the mid-'50s, taking over from the raw, raucous honky-tonk that was at the head of the country-music table in the late '40s and early '50s and setting the stage for the countrypolitan takeover. By the late '60s, producers like Billy Sherrill were defining mainstream country with a sound heavy on orchestrations and massed vocal harmonies. The approach worked for new-schoolers like Glen Campbell, who were grabbing the keys to the crossover kingdom by working with pop songwriters, and by the time the '70s rolled around, the countrypolitan wave was bringing a whole new audience to artists who had been kicking around since the '50s. Singers like Conway Twitty, George Jones and Charlie Rich went from their rockabilly roots and unvarnished, hard-country sounds to cinematic, string-swathed hits that made them superstars in the age of the rhinestone cowboy.