What Is a Subwoofer Capacitor?

A subwoofer capacitor is an electronic component that is used in many audio installations, including home and vehicle stereo systems. Sub capacitors are able to hold a temporary electrical charge. These devices are often used to balance an audio signal, and prevent sudden drops in power.

While batteries are designed to hold electrical power for an extended length of time, capacitors are intended to contain only short-term power. A basic subwoofer capacitor contains two metal plates, which are separated by dielectric, a type of insulator. When there is a voltage difference between the two metal conductors, an electric field may build in the dielectric layer. The stored electrical charge will dissipate rapidly if a proper circuit is connected to the capacitor.

The amount of electrical energy that can be stored in a capacitor is measured in farads. Higher farad capacitors can store more electricity than units with lower farad numbers. Due to the electrical demands of audio systems, most subwoofer capacitors are physically large and feature relatively high farad ratings. The size and capacity of a subwoofer capacitor must be properly matched to an audio system. A capacitor that is too small will fail to provide energy when it is needed, while an oversized unit can cause unnecessary power drains and overload the electrical circuit.

A subwoofer capacitor is often installed in audio setups that use large amplified subs for bass. Each time a large subwoofer activates, a high amount of electricity is drawn from the audio system. This sudden electrical demand is often a problem in cars with limited power, which must be provided by the vehicle’s battery and alternator. The headlights in cars with large subwoofers can dim with each bass hit. This subwoofer power drain can be both distracting and hazardous.

This problem can be limited by providing a burst of electrical energy every time the sub activates. When the subwoofer is silent, the capacitor is able to recharge and prepare for the next power draw. This reserve source of energy often prevents dimming headlights and other power drain problems.

In addition to preventing unwanted power depletion, a subwoofer capacitor can also improve the function of an audio amplifier. Capacitors help regulate the amount of energy that is demanded from the system, and reduce electrical strain on the amp. This allows an amplifier to operate at a lower temperature. Subwoofer capacitors decrease audio distortion and help prolong the life of an amp.