DIATONE DS-5000 manufactured in 1982. 4way　40cm honeycomb cone woofer. 25cm honeycomb mid cone. DUD dome type mid-high. dome type tweeter. frequency 25～40KHz. impedance 6ohms. sensitivity 93db. weight 90kg. 40cm honeycomb woofer is very smooth. combination of four units is very good. This speaker is very energisch and accurate. Please try Japanese speaker. Akihabara shop Tomohiro Kawai