I don't have personal experience with the Rava, but I do have a custom made sub built with the Adire Tempest driver in a 21" cube enclosure. I've compared this one to the Paradigm Servo 15 and the performance is similar. The price is, however, is not. I paid about $900 Cdn delivered for my sub; the Paradigm new is about $2200.

I believe there is a relatively local guy who does Adire products. Check out their website at www.creativesound.ca. The guy's name is Bob Reimer. He even helped me out a year after the sale when I blew out the sub's fuse.