A 6.5" HiVi woofer\mid and Isodynamic ribbon tweeter in a 20Ltr, ported enclosure. Vertical bracing and lined with bitumanised Al foil and Dacron (dampening). Simple 2nd order Xover at 2,350Hz. Lots of bass and goes down to 31Hz in my large listening room. Tweeters go past 22K (tested) Test very flat response. Sounds best with my DIY 300B tube amp. Cost under $400 to build. Sits on my stereo sub-woofers with their own Class D amp.