Woofer output is directly related to the surface area of the cone, for a circle A = pi*r^2.
So a single 12" will give you a surface area of about 36*pi square inches while two 10" will give you about 50*pi square inches (25*pi for each). I'm sure you see the pattern: a single 15" will give you just over 56*pi square inches.
This means two things, first, the single 15" driver is probably capable of more output than the 2 10" drivers, but even more interesting is this: b/c it has a greater cone surface area, the single 15" will have to move less to produce the same output as the two 10" subs. The drivers' suspension behaves non-linearly and so becomes very unpredictable when it moves far from the equilibrium position, this translates into distortion. Regardless of the source material i would rather have the larger driver which needs less excursion to make the same output; this will translate into better sound quality.
With that taken into account, i will usually recommend a single 12" as a compromise between cost, size, ease of intergration (a 15" driver is very large), output and sound quality.
It is a myth that two 10" drivers will be "Faster" than a 12", a 15" or even an 18" driver. Well actually let me rephrase that, smaller, less massive drivers will be better suited for playing higher frequencies, frequencies that you don't want your sub playing in the first place.
Eric
So a single 12" will give you a surface area of about 36*pi square inches while two 10" will give you about 50*pi square inches (25*pi for each). I'm sure you see the pattern: a single 15" will give you just over 56*pi square inches.
This means two things, first, the single 15" driver is probably capable of more output than the 2 10" drivers, but even more interesting is this: b/c it has a greater cone surface area, the single 15" will have to move less to produce the same output as the two 10" subs. The drivers' suspension behaves non-linearly and so becomes very unpredictable when it moves far from the equilibrium position, this translates into distortion. Regardless of the source material i would rather have the larger driver which needs less excursion to make the same output; this will translate into better sound quality.
With that taken into account, i will usually recommend a single 12" as a compromise between cost, size, ease of intergration (a 15" driver is very large), output and sound quality.
It is a myth that two 10" drivers will be "Faster" than a 12", a 15" or even an 18" driver. Well actually let me rephrase that, smaller, less massive drivers will be better suited for playing higher frequencies, frequencies that you don't want your sub playing in the first place.
Eric