"Wally" wrote:

: Don Pearce wrote:
:
: There was a design recommended by Wharfedale back in the sixties that
: used a concrete drain pipe for exactly the purpose you describe. I'm
: sure that with a little searching round the bigger plumbers you could
: find something suitable.
:
: I remember something like that (with the driver mounted in the side rather
: than on the end). I'll be having a wander round the local DIY to check out
: their audiophile-quality garden ornaments...

These look suitably horrible ...
http://www.cornu.de/en/tml.html

I'm sure I've seen similiar constructions elsewhere too.
I do suspect that just bunging anything other than a limited bandwidth sub
into a drainpipe is going to lead to all sorts of complex resonances.

Heavy math references:
http://www.quarter-wave.com/