Wally wrote:

I've been giving some further thought to The Great Speaker Rebuild Fantasy
and I'm presently looking into a Nautilus-style enclosure for the KEF B110
bass/mid drivers. To be clear as to what I mean, this would be a straight
pipe with a reducing internal diameter, the reduction being non-linear. My
current sketch has a start diameter of 180mm, 40mm at the small end, and is
400mm long.

Your transmission line should be about 1.5 m long for a B110.
It has a surprisingly low resonance.

--
Roger.