Recommended sub box size?

RMaddGT said:

I have a relatively low space for trunk room but I want t ported enclosure and the recommended vented box volume is about 1.25 cu/ft for one sub and the sub is alpine type r-1221D and I wanted to know what would be the best box for dual 12''. The height cannot be more than 13.5" in so and the depth can't be much more than 13.5" so I can get it in there and possibly 33" wide, Perhaps I could angle the box or some manner... thanks for advice...

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Just shoot for about 1cuft per sub, mabey a little less if you like more SQ

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302stang said:

For this sub a ported box of 1.25 cubic feet is pretty small, and you should not go under this. Going bigger would be even better, something like 1.5-1.8 cuft. The box has to have an even bigger internal volume than this to make up for the displacement of the sub and the port(s). The space that you said you have(13.5x13.5x33) is about 3.5 cubic feet and taking into account box wall thickness, port volume, and the displacement of the subs you should have enough room for around 1.25 cuft per sub.




For SQ with a sealed box, bigger is better, not smaller. Bigger sealed boxes will play lower, have a higher efficiency, and have a faster transient response than a small sealed box. For a ported box you want to use the recommended size otherwise either too small or too big will hurt SQ.

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155dB5.0 said:

I beg to differ bigger boxs are sloppy and not as acurite as a smaller seald box. When i stated 1 cuft i asumed the distplacment of the sub would allready be subtracted. The best thing to do would be to get build a ported Box for the subs, it will be louder, more efficent and sound better in my opion.

Darren

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302stang said:

This is a common myth but is wrong. Smaller boxes will increase the response in the upper bass frequencies and start to become peaky or boomy. As a sealed box gets smaller the Qtc value rises, which hurts its low frequency response and also increases the transient response of the speaker. With a bigger box the Qtc will get lower and the transient response and low frequency response will improve. Look at the following link to see how frequency response changes with Qtc. http://www.loudspeakers101.com/SealHelp.htm For the best sound you want the frequency response to be as flat as possible, which means about a Qtc of .707 for a woofer than plays up to several hundred hertz. For a subwoofer that will only play up to 75 Hz or so, you get the flattest response by having as low a Qtc as possible. And remember to lower Qtc you increase the size of the box and to maximize it you mount the sub infinite baffle.

Some people may prefer the sound of a small box because it plays midbass frequencies louder and their other speakers don't play these will. But a subwoofer should only play up to about 75 Hz because higher than this the sound starts to get directional, and to sound best these frequencies should only be played with the front speakers. Also since a car has a gain at lower frequencies because of the small interior, the loss in response by the subwoofer may be made up by, by the cabin gain.

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