the most obvious advantages are very low group-delay and a phase-shift favourable to normal ported enclosures while output is as good as a normal ported enclosure or better. a good flat response , and deadly accurate , disadvantages are a very steep roll-off, below tuning it very quickly has no powerhandling at all and the box is not by any means small. *edit* glad I could take you down memory lane Thumpper That makes sense, that clarifies what I read last night on folded horns.