Originally Posted by GT500 MC
5%? That's crazy. Why so inefficient?
Because the speaker motor is an electromagnet. Consider an energized voice coil driven by the amplifier within the air gap of a permanently charged magnet. The losses in this magnetic medium are signifigant. The resistance of the voice coil wire is a necessity to create a magnetic field. That resistance is automatically a little toaster oven. Then you have the mass and inertia of the speaker's moving parts plus other inherent resistances. Compare the mass (weight) of a moving diaphragm and all its attachments to that of air. You are transitioning from electrical power to mechanical motion and then to acoustic energy and speakers do not couple to air all that efficiently. A transducer transforms through three mediums. And much of that remaining 95 % loss is heat.
It's a bit of a shocker when you consider that a highly efficient Class D amplifier may be 80 percent efficient.