Pioneer TS-D12D2 12”
Rotella's Friends sounds tight, musical and exceptionally well defined, which pretty much describes the overall sound character of the woofer in a sealed box.
Then I switched to the vented type of enclosure, and the character of the woofer changed just as you'd expect. One important note when using a vented enclosure is to make sure you have a properly tuned subsonic filter on the amplifier. This ensures the woofer does not “unload” below the enclosure's tuned frequency, which in my case was 36 Hz.
A little of the very low frequency extension was missing, but the output was louder in general and had a musical punchy characteristic. This is exactly what the fans of vented enclosures are