Sensitivity
Sensitivity determines the loudness of the subwoofer when a signal of a certain power is connected to it: with equal signal power and impedance (see below), the subwoofer with the higher sensitivity will sound louder.
Resonant frequency
The natural frequency of the cone in the subwoofer speaker, namely the frequency with which the cone will oscillate if the speaker is suspended freely in the air and a single impulse is transmitted to the cone (for example, by clicking on it with your finger). In subwoofers, this parameter determines, in particular, the lower limit of the frequency range (see above): at frequencies below the resonant sound power drops sharply. Accordingly, for deep rich bass, the resonant frequency should be as low as possible. This parameter is also used to calculate the size of the enclosure for the subwoofer.
Woofer Depth
The size of the subwoofer's main speaker from the front (usually the bezel that protrudes beyond the cone) to the rear edge (where the magnet is usually located). In fact, it matters when selecting cases for frameless models, as well as installing Free Air (see "Execution"): it is at this depth that the speaker will be "drowned" in the case or in the boot. And not always a
flat subwoofer will produce less bass than its more voluminous counterpart.
