ESS Super Quad---the original Quad ESL as midrange driver, RTR ESL tweeters, and a KEF B139 woofer in a transmissionline enclosure. Not many made and sold in the early-mid 70's. The Fulton "J" loudspeaker, a modular design achieving superb transparency and very full-range extension. It, like the ESS Super Quad, had the RTR ESL tweeters, State-of-The-Art at the time (mid-70's). And the Eminent Technology LFT-6---three LFT (Linear Field Transducer) bass/midrange drivers and two ribbon tweeters.