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Rule of thumb:
Larger ported box will peak closer to tuning, and will handle gobs of power in that area. If you go too large you lose control of the woofer at any freq and alot of SPL. Generally these boxes are peaky - depends a bit on woofer.
Small ported box will peak farther from tuning, sometimes this is what you have to do to get a high note. If you go too small you lose tons of output and any semblance of SQ. Generally you can't get a low note out of a small box... you can "tune" to 20hz if you wish, but it will still peak much higher.
Large sealed box gives a great low end at the sacrifice of power handling, perhaps the lowest power handling of any box, assuming the "proper" box is built.
Small sealed will handle more power than a large sealed, but it will sacrifice more low end as you get smaller. Mechanical power handling is less than a ported box, thermal handling may be raised due to increased cone excursion yielding better heat dissipation per the power input applied... but thats obviously only good up until the woofer bottoms out //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
You are more than welcome to test my "rules of thumb" if you wish, be sure to post results here //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif . Please note these things arent written in stone, and slightly large to one 12" driver may be entirely oversized to another... and right on target for one woof may be half the size needed for another woof. The terms "large" and "small" are left purposely vague.