Advantages:
- Efficient - Speaker cone movement is greatest for a given input signal
- Tuning port allows contouring of frequency response
- Bass response and boost from port tuning can be thunderous
Disadvantages:
- Speaker is not damped by box, so bass is not quite as accurate
- Improper port design can annihilate a speaker well under its RMS power rating
- Response curve is usually nonlinear at port tuning frequency
The vented or ported subwoofer enclosure is best suited to electronic music such as rap or electronica where punchy, responsive bass is not as important as deep-reaching, longer bass notes are. Vented enclosures are also best when you don't have as big an amp as you'd like. As the most efficient sub box design, a ported enclosure will give you a higher spl per watt than other designs.
One must be cautious selecting drivers, when buying a prefabricated vented subwoofer enclosure: If the resonant frequency of the box is not well matched for the subwoofer driver you select, uncontrolled resonance can ruin your sound quality or even destroy your subwoofer. If you are driving the sub with nearly its maximum recommended power, be cautious using a ported box and pushing the sub to its limits. The enhanced output the vented subwoofer enclosure design offers may well cause your speaker cone's excursion to go beyond its design - causing mechanical noise and eventually destroying the subwoofer.
The subwoofer cone can begin wildly oscillating, moving far more than it ever would based on amplifier power alone. While this makes for some impressive youtube video, it is not good for your speaker or sound quality. Some speakers simply won't work in some ported boxes.
It is best to consider the size box you are willing to accomodate, then select a driver that works well in a vented enclosure of that size. All decent websites list this information for the drivers they sell - or, visit the manufacturer's website and look for the specifications for your subwoofer there. Finally, after deciding on a driver, use either the manufacturer's specifications for a ported enclosure, or download the software from the links on this site to design your own. When using the freeware sub enclosure tools, graph the frequency response of the sub and enclosure combination, and make any necessary alterations to keep the resonant response from sending your cone into orbit.
Typical Ported (Vented) Enclosure Volumes for Common Subwoofer Sizes 6.5-inch Subwoofer Driver
ranges from .2 cu ft - 1.0 cu ft
8-inch Subwoofer Driver
ranges from .4 cu ft - 1.5 cu ft
10-inch Subwoofer Driver
ranges from .6 cu ft - 3.5 cu ft
12-inch Subwoofer Driver
ranges from 1 cu ft - 6 cu ft
15-inch Subwoofer Driver
ranges from 1.5 cu ft - 8 cu ft
