Rated power
The average (root mean square — RMS) power of the input signal, at which the subwoofer is able to work continuously without negative consequences (damage, failure) for at least an hour. The rated power of the subwoofer must be greater than the power of the amplifier connected to it — in order to avoid overloads.
Max. power
The maximum signal power that the subwoofer is able to withstand for a short time (up to several seconds) without any negative consequences. When selecting an amplifier-subwoofer pair, it is recommended to take a subwoofer with a maximum power of at least twice the maximum power of the amplifier. In general, the higher the maximum power, the more resistant the subwoofer is to overloads.
Frequency range
The range of audio frequencies reproduced by the subwoofer. It is believed that the human ear is capable of perceiving a frequency range of the order of 16 – 20,000 Hz, but in this case note that the subwoofer is designed to reproduce the lower frequency band (up to 200 Hz). Accordingly, in the case of the lower limit of the range, everything is simple: “the lower, the better”; the upper one should not be lower than the lower limit of the main car audio — otherwise there will be "gaps" in the frequencies, which will affect the sound quality.
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.
Impedance
The electrical resistance of a subwoofer when a signal is applied to it. This parameter is important primarily for selecting a subwoofer-amplifier pair: at a lower impedance than that of the amplifier, the subwoofer will distort the sound, at a higher impedance the sound will be too quiet.
For dual voice coil models (see above), the impedance is specified for one of the voice coils.
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.
Subsonic filter
The presence in the subwoofer
of an infra-low frequency filter (Finch), also referred to as Subsonic. This filter "cuts" subsonic frequencies, preventing the subwoofer from reproducing them. Often this filter has a frequency control. This feature serves several purposes. Firstly, the human ear is no longer able to recognize such vibrations, and there is no point in reproducing them — this only leads to useless expenditure of energy. Secondly, intense infrasound can adversely affect well-being (both physical and mental). Thirdly, working with infra-low frequencies at high power can damage the subwoofer itself: figuratively speaking, the coil “blows” off the speaker.
Remote control
The remote control allows you to control the functions of the subwoofer from a distance. This is especially useful if the device is installed in the boot or otherwise difficult to access — you can easily change settings without access to the subwoofer itself, including while the car is moving.
Protective grille
The presence
of protective devices in front of the main speaker of the subwoofer — this can be the grill itself, metal rods, plastic elements, etc. Such devices protect the device from foreign objects to a certain extent, and they can also play an aesthetic role.
