You're right - I chose my words poorly. The first 3 dB increase comes
from the doubling of input power, and the second 3 dB increase comes
from adding a second subwoofer in phase with the first, "correlated",
as you described in your tech notes. The doubling of cone area is a
by-product of adding the second sub, not the source of the 3 dB
increase.

Also, as you pointed out, the overall 6 dB gain is a theoretical
maximum. The actual increase will likely be less, although how much
less is impossible to tell. I would still predict the overall gain to
be at least 4-5 dB.

Interestingly enough, the post of mine you quoted below was the only
one where I described the phenomenon correctly, attributing the second
3 dB gain to doubling the number of loudspeakers, and not mistakingly
referring to it as "doubling the cone area".

Scott Gardner


On Mon, 29 Dec 2003 17:00:11 GMT, Eddie Runner
wrote:

http://www.installer.com/tech/conearea.html
it has nothing to do with CONE area and power doubling!


Scott Gardner wrote:

Bandit 2941 was missing the point. Here's his quote:

"So that should work for subwoofers the same way, so adding a second
subwoofer powering it exactly the same as the first will yield a 3db
gain."

He's recognizing the 3 dB gain from doubling the power, but ignoring
the additional 3 dB gain from doubling the number of speakers.

Scott Gardner