Why Does The Lab Horn use Two Woofers?

[john van ommen]

Tom Danley's labhorn uses two woofers on a single throat. So I thought it would be interesting to find out what happens when this is done.

Conventional wisdom says that a pair of woofers will handle twice the power, but with 6db more voltage sensitivity. I've modeled a pair using Martin King's worksheets, and it seems that the conventional wisdom is correct. The SPL is a *little* different, which makes me wonder if there's any advantage with a more restrictive throat or mouth.

What do you think?

:: JD ::

If anyone's interested, this is how I modeled a pair using King's worksheets:

FS is the same for a pair.
QES is the same for a pair.
QMS is the same for a pair.
QTS is the same for a pair.
VAS is double for a pair.
MMS is doubled for a pair ( MMS = 1/(2 * pi() * FS)^2 * CMS )
CMS is halved for a pair (is that right?) ( CMS = VAS / ( 1180 * ( 343^2 ) * SD^2 )
RE is double for a pair.
SD is double for a pair.
*voltage* efficiency is 6db more for a pair. In the graphs, i did series wiring, hence the same SPL.
EBP is the same for an iso pair.
BL is double for a pair. (Note that motor strength has DOUBLED though! Motor strength is BL^2/RE.) ( BL = sqrt ( RE / QES ) * sqrt ( mms / cms ) )