Hello Vathek et al,

Thanks for all the info. Tried to reply earlier but there seemed to be a technical hiccup. Just saw some 311-90's on epay, someone already bid $800! I'll keep looking. Actually built some midrange tractrix horns years ago, using laminated paperboard in a square crossection. Well damped. The mouth was 2' x 2' for a 120Hz cutoff. As i recall, the mouth circumference needs to be = to the wavelength at cutoff. So a 200Hz tractrix horn would be about 22" in diameter and 26" long. Well it'll still fit in the rec room. Of course I'm wasting some time wondering if I could build the horns.

Yours, JG