Muneed bhai, I really do appreciate your detailed response. And I agree to your understanding.
But there is one big confusion most of the PW community have developed.
We have considered the DB gain inherent in a ported design at Fb to be associated with the term TUNED.
Thats not the case. The term tuning is to be associated with COMBINED SYSTEM RESONANCE. In light of that, both systems (ported as well as sealed) resonate at certain frequencies. And both can be TUNED.
One with just the volume and one with volume plus port area.
The ported enclosure has minimum cone movement at resonance and offers a Gain.
The sealed enclosure has maximum cone movement at Fc and offers close to no gain.
F3 (althoug the -3db mark) is also used a safety limit especially for ported, if we go below, there is a higher chance of damaging the sub due to increased cone movement (under increased power offcourse) as there is no port contribution to support the system
However, in sealed, the roll-of after F3 is 12db that still is fairly safe since the air inside the box acts as a suspension (throughout all frequencies) to prevent Xmax from occurring
@shabmr
Sorry for hijacking your thread. But this understanding (regardless if its on my part or whoever) needs to be resolved. And that too by argument and science (Electronics + Acoustics)