Beaming is not about bass, it's about uncontrolled dispersion. When you move around different parts of the room, you will hear gross issues in FR. Like I said, you may not even notice it that much...
What you were probably hearing was the typical Philips fullrange peaky sound signature, and once you cut the extra HF, you can hear it producing some bass. The bass was always there, just masked by the HF.
Actually, Fs is not a part of the T/S params, those are VAS, Qes, Qts, BL, mms etc. They help in designing a box for correct system compliance. The only thing needed for an OB is the Qts, so you know whether it will work in OB or not as low Q drivers do not work well there. Both Fs and xmax are quoted separately from T/S.
Most high-Q drivers, for OB use, have a very low xmax due to a stiff suspension required to set up the higher Q in the first place. Also, higher xmax drivers sound worse because of the length of the magnetic gap, with smaller xmax the designer can keep more of the coil in the gap so the driver is working in its linear range.
Mms has no correlation with reflections. It is a measure of the moving mass of a driver, including the air. It (in conjunction with BL) gives a measure of the total compliance of the driver. Or perhaps I'm not understanding where you're coming from?
Q is a measure of energy storage, very loosely speaking. It also is sometimes defined as the strength of resonance. A low Q driver or system will have a prominent and peaky resonance, lower Q drivers and systems will have gentler resonances. The principle is the same for all kinds of system Q - including those you may encounter in inductors, for example, not just speakers.
As a cat plays with a mouse, perchance?
