Originally Posted by RockDoc
6x10 = 66.6 BL x 720cc Vd = 47952
^ almost twice the output capacity of a 4x12"
Forgive me if I'm overlooking something, and understand that math isn't my forte, but if the quotation above is accurate, then couldn't we divide that by two and get: 3x10 = almost the output capacity of a 4x12? That somehow doesn't seem right....
3x10 = 33.3 BL x 360cc Vd = 11988
^ 1/4 the output capacity of a 6x10
You're right, that can't be right. At best doubling the speakers (and amp) can't result in more than 3x the output, and that's only if the system maximizes the acoustic loading effect for a 3dB bonus for a total of 9dB gain. Either the BL product or the Vd has to be rooted for this to work:
If it's the BL factor then:
3x10 = rt33.3 BL x 360cc Vd
= 5.77 x 360 = 2077.4
6x10 = rt66.6 BL x 720cc Vd
= 8.16 x 720 = 5875.8
That's 2.8x more output.
If it's the vD then:
3x10 = 33.3 BL x rt360cc Vd
= 33.3 x 19.0 = 631.8
6x10 = 66.6 BL x rt720cc Vd
= 66.6 x 26.8 = 1787.1
That's also 2.8x more output.
I figure the difference will only become apparent when comparing different sized drivers. You can't just go by the sensitivity specs of the drivers, since in a bass configuration the driver's ability to force a mechanical load is more important than its free-air sensitivity.
This begs another question. When a mechanical load is introduced, it increases the electrical impedance of the speakers too, so perhaps cabs with more smaller drivers are actually higher impedance than indicated. Horn loading does exactly that, the Yorkville LS808 is rated at 8 ohms but uses a 4 ohm driver. I've talked to a Yorkville tech about it on the phone, they insist they've measured their AC impedance at 7.8-8.2 ohms. Maybe 4x10's should use 6 ohm drivers found in 3x10's...