[bossobass]

Since I've read the general statement that tubes are more rigid than cubes more than a few times, I thought I'd chime in with some thoughts on the subject.

The popular tube is the paper concrete form type. The walls are relatively very thin.

I think a good illustration would be to turn a cube on it's side and sit on it, then turn the tube on it's side and do the same. Certainly, the cube would show no signs of stress under this test, but how would the tube fare?

The tube is only as rigid as the end caps make it so, but...as you increase the length of the tube, the cap has less and less of an effect towards the middle of the tube.

The simple truth is that thin-walled tubes are definitely not more rigid than thick-walled, properly braced cubes in the context of a very large diameter paper based tube that is 5-6' long.

The tubes flex rather easily in comparison.

Also, as SteveC brings up the 'why sacrifice part of the BW to chase single digits?' argument in every place he visits, I'm compelled to comment on that subject as well...

Whether you use a Bi-quad filter or a simple shelf filter to apply a boost curve to a sealed sub's input signal, you get the same effect below the resulting new F3 of it's anechoic FR...a second order roll off.

When using a Bi-quad, you get the added benefit of choosing the F6 BW, or knee, as it may suit your own listening tastes. You may even easily design more than one shape of knee in a user-selectable Q feature. Below that knee, whatever the F6 BW may be, the result is a second order roll off.

A second order roll off just happens to work well with an enclosed listening area to result in a 0 order roll off, or a flat response, so, there is no 'chasing' of anything. It's simply a positive consequence of the alignment.

You give up nothing to achieve in-room response to single digits with a sealed alignment. The in-room response is...flat...to single digits. A simple 2X15" sealed, EQ'd system is plenty of low end for the vast majority of listeners and the average satellite system. If 'compression' (assuming we mean power compression) is limiting the system at 20Hz (because it's an atypically large room, or the listener prefers a boosted low end FR curve, etc.), more system is needed. The system's in-room capabilities below 20Hz have nothing to do with compromising the design.

OTOH, the currently popular LLT design definitely compromises output in the 30-50Hz region to chase lower frequencies, as well as real estate, which ties into the first comments in this post, because, as I said, as you incrtease the length and diameter of the tube, you also compromise it's rigidity.

Bosso