Car Audio Amplifiers by Channel Count

Channels and class: matching the amp to speakers or sub

A mono amplifier drives a subwoofer, a two-channel amp a pair of speakers, and a four-channel amp front and rear speakers. Two channels can be bridged into one for more power into a single load, but check the minimum impedance in bridged mode. Class D is efficient and runs cool, which is why it dominates subwoofer amps and compact designs; Class AB is the traditional choice for full-range speakers and runs hotter.

RMS power, impedance and the wiring needed to feed it

Compare continuous RMS power at a stated impedance, such as 4 x 185 W RMS at 4 ohms, rather than a maximum figure. Aim for an amplifier whose RMS output is close to your speakers' RMS rating. The amp must also be stable at the load you wire. Feed it with power cable and an inline fuse sized to its current draw, a short solid ground, a remote turn-on lead and signal cables.

Questions about Car Audio Amplifiers by Channel Count

Can I connect an amplifier to a factory radio?

Yes. If the radio has no pre-outs, use an amplifier with speaker-level inputs or a line output converter. A factory radio's signal is low, so set the amplifier's gain carefully to avoid distortion.

How much power should the amplifier have for my speakers?

Look for an RMS rating near, or a little above, the speakers' RMS rating at the same impedance. Too little power clips and can damage speakers; some headroom keeps the sound clean.

Where should I mount a car amplifier?

Choose a spot with airflow, such as under a seat or on a rear-deck panel, and avoid burying it under carpet or cargo, because amplifiers need to shed heat. Mount it firmly, and keep power cables away from signal cables to prevent noise.