Rated power
Rated power of the acoustic system. Most often, the average (root mean square) sound power is indicated as rated.
The most obvious point related to this characteristic is the volume of sound: the more powerful the sound system, the louder the sound it can produce, all other things being equal. In addition, compatibility with an external amplifier depends on this indicator: its power should not exceed the power of the sound system, otherwise overloads and damage to the speakers are possible.
Max. power
The maximum power of a short-term (up to several seconds) incoming signal that the speaker can withstand without physical damage. Just like the nominal power, it matters for the selection of acoustics for an amplifier (or vice versa): it is believed that the maximum power of the speakers should be at least 2 times higher than the maximum power of the signal source.
Impedance
The term "impedance" refers to the electrical resistance of AC systems whose DC resistance is very low, such as loudspeakers. In modern car audio, the most common impedance is
2,
4 or
8 ohms. This parameter has practically no effect on the sound quality — it serves to select the optimal combination of acoustics and an external amplifier. If the speaker impedance is higher than that for which the amplifier is designed, the sound will be quieter than necessary, and if the impedance is lower, distortion in the sound is possible.
