I think they had several different models. I played with some 6"by
6" panels that were usualy used from about 1200hz up. I heard that these could be used down to as low as 800hz but that was
pushing it. The ones I had were surprisingly sensitive. I tried hooking them directly to a 20 watt amp without the step up transformer and I may have gotten 60 db or so !
Great, I will check that site out. Mine are Mod 60s and have 2 panels ea. They are now part of the center channel and sound much better than the old Warfdale 3 an 10 inch pairs that had handled evrything over 3K.