I was wondering if a coaxial or component set(midrange) that people typically install in ther doors or back dash would sound better if they had a sealed enclosure. I know you have to have an enclosure for subs unless its a free air, but how about inside speakers? Would they sound better? Can you get more power from the speakers with an enclosure? thanks..
They might sound better in an enclosure. And that is a big might. Component woofers for cars generally like a bit of space, so door cavities fit the bill pretty well. If you damp all the metal skin inside the door and seal up the panel real well with caulk and tape, you can get a pretty good seal. The problem with enclosures in a car is the size you have to make them; generally smaller than the woofer would like if you want to get them to fit and still have some legroom. The result can usually be found in a diminishment of the low end response, and you would hear this deficiency by the lack of punch in the 80 to 100 Hz region.
It's the bass response, not the midrange, that utilizes the large airspace. Components like 6.5's have the capability of bass response and will blend with the sub bass response. Midranges need very little air volume. It just happens that the 6.5 will produce both bass and midrange response.
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.