"Don Pearce" wrote in message
...
On Fri, 19 Oct 2007 23:28:57 -0400, "Arny Krueger"
wrote:

I don't think anyone is going to call the IMF a small box. But then I
suppose it isn't really a box at all.

The tech analysis of transmission line speakers I've seen say that its
simply a very wasteful way (in terms of volume versus bass extension
versus
efficiency) to make a vented box. That may help explain the large size,
all
other things considered.

No, not a vented box, but an infinite baffle. The idea is that the
entire back wave is absorbed in the line. Nothing comes out of the
vent, and nothing bounces back at the speaker.

That's one variation of the TL. It's been decades since I heard an IMF, so I
forgot which one they used.

However, if its a sealed box TL, then it is easy to explain how it is less
efficient than the plain sealed box. A well-designed sealed box uses the
resonance of the space behind the driver to improve the efficiency of the
driver at low frequencies. Damp this resonance out, and you've lost a lot of
efficiency.

There is a variant in which the line is not stuffed to criticality in
which vent power is used to prop up the low end, but that isn't
strictly a TLS. Forget what it is called right now.

Let's face it, commercial nomenclature can be kinda loose. :-)