I've got a pair of 4312 waiting for me to pick up if I ever get round to it. They have a carbon, or paper tweeter, which I'm told hasn't the greatest frequency response. But for being free hard to beat. Need to replace the woofers though. One was punctured in a move, so I want to replace both. I'm also told I need send a good 250 watts each to them, and an Adcom GFA555 is recommended for that duty.