In Open Baffles, I think that Dick Olsher claims an efficiency for the DX4s of something like 98 db. In open baffles, I use a single inductor as a first order filter to roll off the high frequencies from 500 hz and above. I then have a fairly flat frequency response from 150 hz to the high frequencies (~10 khz).

In Hedlund Horns, the DX4s are flat all by themselves (no filter needed) from 70 hz to the high frequencies (~10 khz). Thus there are no losses in inductors, and I can get down lower.

Retsel