There are basically 4 types of enclosures for subs
1. vented/ported/PR
2. Sealed (acoustic suspension)
3. Bandpass
4. Transmission Line.
Sealed boxes are far and away the easiest boxes to design. They normally have deeper bass at the cost of a little output.
Vented/Ported (the same) are louder at lower freq. but the sound rolls off quicker than a sealed design. A PR acts essentailly the same as a port with a couple of advantages, you won't get wind noise from the port and they are typically 1 dB louder at the tuning freq. than a ported design. The noise factor in car is not really a factor with trunk mounting. PRs are very hard to tune. Ported boxes are also somewhat difficult to do right but with a little experimenting, you should be able to get it right. If you can get me the factory specs, I would be happy to tell you how big of a port and how long it should be.
Bandpass subs are ok for car use. They act as a natural crossover for the driver (you still need an actual crossover) and they tend to be louder than other variations. Their downfall is large enclosures and they tend to make every bass note sound the same.
Transmission Line subs are extremely nice but not practical because of the size needed.
4 cubic feet is huge!!! especially when you get two of them!! Do they recommend only ported?
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99 SVT
Sony ES CDX-C910
Sony Digital EQ/X-over
Sony Changer
McIntosh MC440M
Adire Audio Shiva
MB Quart/Vifa seperates
