# Physics question!

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Hypothetical situation:

I have a rigid panel (let's say it's a piece of plywood) that I attach to a voice coil / motor assembly, so the motor is driving the voice coil. Since its one motor driving a huge and heavy piece of plywood, it's inefficient.

So let's say I attach 3 more identical motors (4 total) to the same piece of plywood, and wire them so that the impedance remains the same. My BL product goes up by a factor of 4 (because I have 4x as much wire in equivelant magnetic gaps). What effects will I see because I do this? Will the efficiency go up? Will sensitivity go up? Will frequency response change? (Assume that breakup modes are negligible.)

What if I went up to 8 motors, wired for 2x the impedance, what would happen then?

#### SY

Well, sound pressure is proportional to BL at a constant Sd...

#### SY

Oh, yes, efficiency. That's proportional to the square of BL, but inversely proportional to the square of the moving mass. So, to see the effect of your extra motors, you'll need to specify their mass relative to the mass of the, errr, cone.

#### Ron E

Voltage sensitivity is proportional to (Sd*Bl/(Mms*Re))^2

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