Back in the 80s and the 90s you needed two or three cubic feet of airspace for a twelve inch driver. As time progressed, people wanted woofers that worked in smaller and smaller boxes. At this point, you can easily find twelves that will work in a half a cubic foot, or even a quarter of a cubic foot.
That creates a problem though. As the box gets smaller, the vent gets BIGGER.
That's why we're seeing a lot of boxes with these outlandish looking vents. It's because we're getting to a point where the vent is bigger than the box itself!
An obvious solution would be to use a smaller vent, but this isn't a good option, because vent efficiency and vent size are tied together. So if you want an efficient vent, it needs to be big.
Taken to the extreme, you end up with a tapped horn, which is basically a vented box with a very large vent and no back chamber at all.
Hope that helps. I've written a ton of posts on this at forum.audiopsychosis.com
There most likely aeroports and there used to get maximum use of small air spaces. This way a guy can enter the class A amateur spl for one woofer or two and with four or more amps (Depending on how many voice coils) they tune the boxes up to 80hz and do very high spl with them.
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This guy (Jacob Fuller, owner of Sundown audio) does some impressive numbers with them. 150.2 "Outlaw" - Single 8" Woofer - DIYMA.com - Scientific Car Audio - Truth in Sound Quality
Well keep in mind that if a port measures 10 inches long and is 4" diameter it will take up that much space in the enclosure and should be accounted for when calculating displacement. It depends on what your looking for in performance. If you want spl or higher decibels they seem to have an advantage when it comes to port turbulence which in the spl world can cause loss of decibels. Although proper port etiquette for me at least is to round over all the edges of any port round or square.
Interesting, I've never heard it from this perspective before.
I was under the impression the ports were mostly for more SPL and as a result loose some sound quality over a sealed enclosure.
Speaking of which, I think the funniest things I've seen are when they put the tweeters, even mids, on subwoofer boxes for cars. What's the point in that? They're usually in the trunk or in the rear and would either be useless or destroy the sound image.
I was under the impression the ports were mostly for more SPL and as a result loose some sound quality over a sealed enclosure.
Speaking of which, I think the funniest things I've seen are when they put the tweeters, even mids, on subwoofer boxes for cars. What's the point in that? They're usually in the trunk or in the rear and would either be useless or destroy the sound image.
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