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<blockquote data-quote="geolemon" data-source="post: 314954" data-attributes="member: 547749">pretty simple...A sealed box is as it sounds... sealed.It&#039;s just a rectangle with a sub mounted in it.&nbsp; The air inside can&#039;t escape.It exists solely to contain that rear-wave energy off the backside of the sub, that is 180 degrees out of phase, and would cancel with, the energy off the front of the sub... to make sure that the sub can perform.Certain subs are ideal in sealed enclosures, many specs of a sub contribute to determining this.A ported box deals with the same issue, but rather than constraining that otherwise-sound-cancelling energy off the back of the cone, it has a length of plastic pipe mounted in it, forcing the escaping energy to travel through a known air-resistive additional distance, effectively delaying the escape of that sound energy, putting it more in-phase with the sound energy coming off the front of the sub, creating in some cases up to 3dB more output than a simple sealed enclosure, the greatest gains occurring near &quot;the tuning frequency&quot; of the enclosure... but losing air spring inside the enclosure as the frequencies drop below the tuning frequency.Certain subs are ideal in sealed enclosures, many specs of a sub contribute to determining this.Bandpass boxes slap on an additional chamber over the front of the sub, forcing all the sound to travel through that &quot;front chamber&quot;s port, which has some benefit if you know what they are (ie. additional boost, acoustical filtering, etc).Important to note that the &quot;rear chamber&quot; of bandpass boxes can be either sealed (4th order bandpass, single-vented) or ported (6th order bandpass, or dual-vented), and that subs may be best suited for one or the other.Check out JL Audio&#039;s <a href="http://www.jlaudio.com/tutorials/magic/index.html" target="_blank">tutorial on enclosure types</a> for more info.</blockquote>

[QUOTE="geolemon, post: 314954, member: 547749"] pretty simple... A sealed box is as it sounds... sealed. It's just a rectangle with a sub mounted in it. The air inside can't escape. It exists solely to contain that rear-wave energy off the backside of the sub, that is 180 degrees out of phase, and would cancel with, the energy off the front of the sub... to make sure that the sub can perform. Certain subs are ideal in sealed enclosures, many specs of a sub contribute to determining this. A ported box deals with the same issue, but rather than constraining that otherwise-sound-cancelling energy off the back of the cone, it has a length of plastic pipe mounted in it, forcing the escaping energy to travel through a known air-resistive additional distance, effectively delaying the escape of that sound energy, putting it more in-phase with the sound energy coming off the front of the sub, creating in some cases up to 3dB more output than a simple sealed enclosure, the greatest gains occurring near "the tuning frequency" of the enclosure... but losing air spring inside the enclosure as the frequencies drop below the tuning frequency. Certain subs are ideal in sealed enclosures, many specs of a sub contribute to determining this. Bandpass boxes slap on an additional chamber over the front of the sub, forcing all the sound to travel through that "front chamber"s port, which has some benefit if you know what they are (ie. additional boost, acoustical filtering, etc). Important to note that the "rear chamber" of bandpass boxes can be either sealed (4th order bandpass, single-vented) or ported (6th order bandpass, or dual-vented), and that subs may be best suited for one or the other. Check out JL Audio's [URL="http://www.jlaudio.com/tutorials/magic/index.html"]tutorial on enclosure types[/URL] for more info. [/QUOTE]

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