by Jonathan » Sun Feb 13, 2005 5:19 pm
I understand, I was just making sure that people didn't think that ported boxes equaled less power handling or more excursion with the same power. It's just a general misconception that sealed=SQ and ported=SPL and worse SQ. Maybe your typical prefab box at Best Buy, but a well built ported box *usually* is superior in the area of mechanical power handling and thermal power handling (since air is able to move in and out of the port), and it offers increased cone control over a sealed box. The downsides are that the ported box doesn't mate well for a flat frequency response due to the cabin gain of the car environment due to cabin gain, in a room you can get a flatter response with ported since it doesn't begin rolling off until it's tuned frequency. Sealed excels for overall flat frequency response and responds more quickly than a ported, and that is the main reason a sealed box sounds more controlled, even though it isn't. There are two ways to look at transient response, how quickly the sub moves (advantage goes to sealed) and how quickly the sub stops (advantage goes to ported). Transient response by definition on the subject of speakers is the ability of a speaker to respond to any sudden change in the signal without blurring (smearing) the sound. A speaker that can react quickly to rapid changes in sound has "good transient response". So increased mechanical control (ported) results in a sub that stops quicker, so less overthrow happens. Sealed offers a sub that responds more quickly than ported, but the properties of the enclosure acting like a "spring" tends to result in more overthrow and increase distortion, especially at high volumes. A small sealed box increases control and mechanical power handling, but the tradeoff is that you lose low frequency extension and the sub responds slower. A sealed box too large will increase response and decrease power handling and control, at a certain point you eliminate the enclosures ability to assist the subs suspension and power handling dramatically decreases. Ported boxes have to be built well with a large port area in order to provide great SQ, if you don't you basically get the performance of a leaky sealed box and a lot of port noise. All in all IMO a well built ported box can sound just as good as sealed, it just takes a little more planning and taking your time building it. For optimum SQ I prefer the Aperiodic membrane, it increases cone control and power handling over sealed and creates a critically damped system that accurately tracks the input signal. You are "tuning" the membrane to mechanically dampen the subwoofer at it's resonant frequency, so it results in a very flat, predictable frequency response and a smoother impedance. It is less efficient than sealed and infinite baffle, that's the main tradeoff.
I understand, I was just making sure that people didn't think that ported boxes equaled less power handling or more excursion with the same power. It's just a general misconception that sealed=SQ and ported=SPL and worse SQ. Maybe your typical prefab box at Best Buy, but a well built ported box *usually* is superior in the area of mechanical power handling and thermal power handling (since air is able to move in and out of the port), and it offers increased cone control over a sealed box. The downsides are that the ported box doesn't mate well for a flat frequency response due to the cabin gain of the car environment due to cabin gain, in a room you can get a flatter response with ported since it doesn't begin rolling off until it's tuned frequency. Sealed excels for overall flat frequency response and responds more quickly than a ported, and that is the main reason a sealed box sounds more controlled, even though it isn't. There are two ways to look at transient response, how quickly the sub moves (advantage goes to sealed) and how quickly the sub stops (advantage goes to ported). Transient response by definition on the subject of speakers is the ability of a speaker to respond to any sudden change in the signal without blurring (smearing) the sound. A speaker that can react quickly to rapid changes in sound has "good transient response". So increased mechanical control (ported) results in a sub that stops quicker, so less overthrow happens. Sealed offers a sub that responds more quickly than ported, but the properties of the enclosure acting like a "spring" tends to result in more overthrow and increase distortion, especially at high volumes. A small sealed box increases control and mechanical power handling, but the tradeoff is that you lose low frequency extension and the sub responds slower. A sealed box too large will increase response and decrease power handling and control, at a certain point you eliminate the enclosures ability to assist the subs suspension and power handling dramatically decreases. Ported boxes have to be built well with a large port area in order to provide great SQ, if you don't you basically get the performance of a leaky sealed box and a lot of port noise. All in all IMO a well built ported box can sound just as good as sealed, it just takes a little more planning and taking your time building it. For optimum SQ I prefer the Aperiodic membrane, it increases cone control and power handling over sealed and creates a critically damped system that accurately tracks the input signal. You are "tuning" the membrane to mechanically dampen the subwoofer at it's resonant frequency, so it results in a very flat, predictable frequency response and a smoother impedance. It is less efficient than sealed and infinite baffle, that's the main tradeoff.