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.
Sensitivity
This parameter determines the volume of the sound of a particular speaker when a certain standard signal is fed to it. Typically, this is considered a 1 W signal with a frequency of 1000 Hz. The higher the sensitivity, the less the speaker is demanding on the power of the amplifier. So, it is believed that for acoustics connected directly to the car radio, the sensitivity should be 80 dB or more; for less sensitive systems it is recommended to use a separate amplifier.
Tweeter size
Size of the high-frequency speaker(s) included in the speaker design.
Size affects the amount of space required to install the speaker. However, high frequencies do not require large diffusers, so this dimensions is usually small and does not significantly affect the overall dimensions of the speaker system. The only exception is individual high-frequency tweeters (see "Type"), where the overall dimensions of the housing are directly related to the dimensions of the diffuser.
Woofer size
Size of the low-frequency speaker(s) provided in the speaker system.
This size is specified only for models with separate bass speakers. In such acoustics, it is the LF emitter that is the largest (this is due to the physical characteristics of the bass range). Accordingly, the space occupied by the entire system is determined mainly by the diameter of the LF speaker. And since the power and richness of the bass also directly depends on the size of the emitter, then when choosing, you have to proceed from a compromise between the capabilities of the acoustics and the available space in the car.
Mounting depth
The mounting depth of car audio is, in fact, the size of the speaker in depth. Note that for component sets (see "Type") this parameter is given for the largest speaker, and for case models it is generally irrelevant.
The mounting depth, along with the diameter of the speaker (see above), determines the amount of space needed to mount the speaker — in this case, how deep a niche would be required for normal mounting. At the same time, the larger the speaker, the larger, usually, the installation depth. And with similar diameters of equal size, a more powerful model is likely to be more “deep”.
The smallest amount of space —
up to 15 mm deep — is required by some tweeters. A depth
of 16 – 30mm is normal for tweeters and very shallow for general range speakers, most of these models have a depth
of 30mm or more. At the same time, full-range speakers are usually "recessed" by
less than 60 mm, component systems — by
less than 90 mm, and
more depth may be required only for some coaxial and mid-range models and, oddly enough, tweeters.
