I would refer you to a google search and Martin J. King's site on
transmission lines, which includes some modeling software.

There are other sites with modelling software to be found for TLs.

If the FS of your 'mutt' drivers is not fairly low, then you may merely
have found a room node which you managed to excite. Try taking
the boxes (tubes) outside and see what they measure.

_-_-bear

ludovic mirabel wrote:

I'd like to solicit the opinion(s) of knowledgeable readers.
As I recounted recently I made two transmission line woofers,
each consisting of two "sonotubes'" (compressed paper cylinders)one
inside the other with a 12" woofer (Electrovoice frame and Altec
Lansing cone). The whole enterprise is very primitive and just within
my very limited aptitude for jigsawing and so on.


snip

The brief version is:

a) absorb all the backwave (in effect) making it an infinite baffle.
(usually called a labrynth, iirc)
or
b) tune the backwave to like a lowish Q organ pipe and excite it.
(usually called a "Tranmission Line", iirc)

iirc...

_-_-bear


(Please make it as simple as possible).
Ludovic Mirabel