15s Rule!!!
EDIT: Someone once asked -
If speaker size does not affect tone, why do they exist?
Because some larger speakers move more air, handle more power, have better venting and etc. For example - just because an 8” woofer may be able to cover the same freq.‘s as a 15” woofer doesn’t mean it can do it at the same volume level (SPL) as a good 15" woofer - that’s the reason why there are no high power sub woofers the size of a dime.
This is what Eminence engineers say ~
Generally speaking, the number one contributor to a transducer’s power rating is its ability to release thermal energy. This is affected by several design choices, but most notably voice coil size, magnet size, venting, and the adhesives used in voice coil construction. Larger coil and magnet sizes provide more area for heat to dissipate, while venting allows thermal energy to escape and cooler air to enter the motor structure. Equally important is the ability of the voice coil to handle thermal energy. Eminence is renowned for its use of proprietary adhesives and components that maximize the voice coil’s ability to handle extreme temperatures. Mechanical factors must also be considered when determining power handling. A transducer might be able to handle 1,000W from a thermal perspective, but would fail long before that level was reached from a mechanical issue such as the coil hitting the back plate, the coil coming out of the gap, the cone buckling from too much outward movement, or the spider bottoming on the top plate. The most common cause of such a failure would be asking the speaker to produce more low frequencies than it could mechanically produce at the rated power. Be sure to consider the suggested usable frequency range and the Xlim parameter in conjunction with the power rating to avoid such failures. <snip>
http://www.eminence.com/support/understanding-loudspeaker-data/
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Generally - speaker size also matters when it comes to moving air (SPL) - cone area.
How to calculate cone area.
Cone area = pi x (r x r)
pi = 3.14 r = radius of sub
# 8” 10” 12” 15” 18”
-----------------------------------------------------
1 50 78 113 176 254
2 100 157 226 353 508
3 150 235 339 530 763
4 201 314 452 706 1017
5 251 392 565 883 1272
6 301 471 678 1060 1526
7 351 549 791 1236 1781
8 402 628 904 1413 2035
NOTE: All numbers rounded down to the nearest inch.
Drivers, enclosures, power, etc all are factors - and speaker size does matter when it comes to moving air (SPL), etc and shouldn’t be downplayed. And remember the cab is built around the driver and not the other way around.