Transformer single stage output ratios

[Mike Watterson]

You can see what a horn is like by using phone/media player and regular earphone to drive it. It acoustically matches to room and LF cut off lower and directivity more as aperture increased. Exponential is best, but a simple cone will work.

You can stiffen the paper with PVA on one side and varnish on the other for a horn. A cone for moving iron "motor" doesn't need stiffening, though a light spray either side of varnish to stop it getting soggy in long term might help.