"You are a good sport and I hope you knew I was "teasing you"."

With you Ed, one is never sure. But I suspected that was the case.

"Just for kicks....in a BR the woofer cones are at minimum excursion at port tuning (a good thing)......or so I thought. What happens below port resonance? Does not the driver become "under damped" and "kind of flop around" (a very bad thing for a single driver speaker)? And if the content you are listening to has significant output below port tuning (common) wouldn't that cause excessive excursion and maybe even limit SPL (due to audible distortion) in a single driver speaker? Is my understanding of this wrong?"

You are correct. I once bottomed a 10" Focal woofer in a BR playing the 1812 cannon shots. I made it to the volume control before any real damage was done.

If you think about it, a BR unloads the driver below resonance because it is acting like an open backed speaker. A TL or ML TL does the same thing, although having stuffing helps a little to damp any ringing. But if you think a little harder, you will also recognize that a BLH has the same problem as a BR at very low frequencies. A BLH does not prevent unloading the driver below the line's first resonance.

The jazz I listen to does not have much bass content below 40 Hz so I really don't have too many concerns about my drivers in ML TL enclosures going unstable. Since we did a way with turntable rumble (much better turntable and CD players) I have not seen BR enclosures unload very often, at least in my system.

Martin