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<blockquote data-quote="Immacomputer" data-source="post: 5581190" data-attributes="member: 570419">That is not the case. Around the tuning frequency (about 1 octave above and 1/2 octave below) the sub will see a acoustical impedance which will create a pressure build up inside the enclosure. The pressure will be released around these frequencies through motion of the port air mass. When you play frequencies about 1/2 an octave below the tuning frequency, there isn&#039;t an acoustical loading on the sub and the sub will have to rely on it&#039;s own braking for cone control. So no, the ported box will not magically stop all sounds below the tuning frequency but cone control becomes degraded which makes LFE more difficult.The low frequency extension that&#039;s going to be possible from an enclosure will rely on the enclosure layout and design (which will affect the front wave and rear wave phase relationship), driver being used, and the environment its in.I&#039;ve seen ported enclosures tuned to 28hz only be able to really drop to about 35hz before loosing output and I&#039;ve seen enclosures tuned to 35hz play flat down to 22hz with no problems.It&#039;s the frequency at which the air mass in the port resonates naturally. It will also be the frequency that has the least amount of cone movement.</blockquote>

[QUOTE="Immacomputer, post: 5581190, member: 570419"] That is not the case. Around the tuning frequency (about 1 octave above and 1/2 octave below) the sub will see a acoustical impedance which will create a pressure build up inside the enclosure. The pressure will be released around these frequencies through motion of the port air mass. When you play frequencies about 1/2 an octave below the tuning frequency, there isn't an acoustical loading on the sub and the sub will have to rely on it's own braking for cone control. So no, the ported box will not magically stop all sounds below the tuning frequency but cone control becomes degraded which makes LFE more difficult. The low frequency extension that's going to be possible from an enclosure will rely on the enclosure layout and design (which will affect the front wave and rear wave phase relationship), driver being used, and the environment its in. I've seen ported enclosures tuned to 28hz only be able to really drop to about 35hz before loosing output and I've seen enclosures tuned to 35hz play flat down to 22hz with no problems. It's the frequency at which the air mass in the port resonates naturally. It will also be the frequency that has the least amount of cone movement. [/QUOTE]

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