Please Read and express your feelings and opinions....

@atmasphere

You’re using the wrong formula - equating electrical power to sound power. The db formula for sound power is :

10 X log 10 (P/Po) db

where P is the measured sound power and Po is the reference level.

If you doubt me, look it up. I believe it’s spelled out pretty clearly in Wikipedia.

And sound power is a function of the force applied, (in this case the voltage) along with the area and displacement over which that force is applied. When you halve the force and double the area, you wind up with roughly the same sound power that you began with. But improved acoustical coupling with increased area improves net efficiency (electrical power in versus sound power out).

You’re using the wrong formula - equating electrical power to sound power. The db formula for sound power is :

I was using the right formula as I was referring to amplifier power, not sound pressure and was pretty clear about that.

When you halve the force and double the area, you wind up with roughly the same sound power that you began with. But improved acoustical coupling with increased area improves net efficiency (electrical power in versus sound power out).

Again, halving the **voltage** reduces the force to 1/4th.

" Again, halving the **voltage** reduces the force to 1/4th. " - atmasphere

Really? Are you serious? What do you think voltage is, my friend? Voltage is "electro motive FORCE". Halving the voltage does not reduce the force to 1/4. It reduces power to 1/4 since the formula for power  expressed simply with voltage and resistance is:

V squared divided by resistance.

Look, I didn’t come here to give lectures on Electrical Theory Basics. This is getting embarrassing. Please review your textbooks. I can’t continue to carry on a technical conversation with you if you fail to grasp the basics.

When is a force not a force? When it’s a voltage. Electromotive force is not (rpt not) a force, as fate would have it. Otherwise, Volts would have units of pounds or kilos or grams or whatever. It’s not the voltage that throws you across the room. It’s the amps, baby,!

Really? Are you serious? What do you think voltage is, my friend? Voltage is "electro motive FORCE". Halving the voltage does not reduce the force to 1/4. It reduces power to 1/4 since the formula for power expressed simply with voltage and resistance is:

The problem here is that voltage does not exist without current. The two together are power. Even though we refer to speakers as 'voltage driven' that is a bit of a charged term (referring to the fact that many amplifiers are designed to act as 'voltage sources' and many speakers are designed to expect a voltage source to be driving it); but in fact power is actually making the speaker move. If you can somehow make a speaker move with voltage but *without* current, you will have a new branch of physics :)

A 3db reduction is halving amplifier power, which is what drives a loudspeaker. Its the 'force' that makes a speaker move and because of that if you reduce the voltage by half, the power to move the speaker is reduced to 1/4 of previous.