I don't quite agree. Once you have stuffed the backside of the driver into an airtight compartment, it is truly a sealed subwoofer. And making airtight seals around ports is making the enclosure into a sealed subwoofer. You no longer have any of the advantages or disadvantages of the ports. The onus is entirely upon the driver to produce sound. The only problem with sealing the ports of a subwoofer that was intended to be run in ported operation is that the enclosure and electronics were geared for ported operation, so the configuration wouldn't be optimal for that alignment with that driver. But acoustically speaking, it is a true sealed subwoofer.\n\n\nIt becomes a true sealed subwoofer, but the driver which is designed for a ported box will not perform as well when performing in the sealed cabinet. The most obvious result will be an overall reduced efficiency, a raised cone resonance and a higher frequency roll off knee, but at a 12 dB instead of 24 dB per octave..