'Rumble' by Link Wray was banned from the radio for being 'too heavy''. The powers of the time thought it would incite riots. Today, most music is 'heavier' than Rumble. Records of the vinyl era had limited potential for bass frequencies because the needle would literally jump out of the groove. You can't have a proper discussion about what makes heavy heavy without taking into account what was considered heavy in the past. Black Sabbath's old recordings may sound light, but at live shows they had full stack amplifiers and large PA systems that made it even heavier.
