audioholic
5,000+ posts
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Cone angle, sometimes referred to as cone depth, does not alter cone area of a speaker. A massively deep speaker with an OD of 12" has no more effective radiating surface than does a flat coned 12. You can ignore cone angle completely, and basically just look at cone diameter to compare different drivers. The only thing using the simple method of calculating Pi*r^2 will miss is the surround and how it affects the radiating surface area.I'm just going off of Fi's specs. 1240cm^2 for the four 10's and 1210cm^2 for the 18.
OP: Sd isn't just a flat thing that you can measure by looking at the radius of a woofer, cone angle comes into play as well. And if you're going to do the whole pi(r^2) thing, take 3" off of each normal-sized woofer's diameter since you have the mounting ring an surround on each side to consider when looking for a somewhat accurate idea of the cone size.
Or just look around for normal sd measurements on different size woofers.
