Wednesday, 4 November 2009

Choosing an Amplifier

The addition of an amplifier and suitable speakers can enhance any car audio system. In this article we will cover the most of the decisions that need to be made when choosing an amplifier for your car.

How Much Power?

Some people will say that you can never have enough power! The power output of the amplifier will ultimately govern the maximum volume that will be available in the system. However the power output of the amplifier must be carefully matched to the power that the speakers can handle. The values that should be matched are the RMS output value of the amplifier and the RMS input value of the speakers. Speakers often supply the peak music input power as well but this shouldn't be confused with the RMS value. The peak value is the power that the speaker can sustain for short bursts but not continuously.

If the RMS input power of the speaker is regularly exceeded then it will lead to premature failure of the speakers which will probably be caused by a mechanical failure.

How Many Channels?

The number of channels correspond to the number of speakers that can be driven from a single amplifier. The most popular choices are either 2 or 4 channels.

4 channel amplifiers often give the ability to create a bridged connection. This is where 2 channels are combined to give approximately twice the output of a single channel. This gives some flexibility in the system for example you could use 2 channels to power the high/mid range speakers and a single bridged channel for the sub-woofer to give some extra depth to the sound.

Amplifier Inputs

One common problem that maybe experienced is when the factory head unit is to be maintained. The input connections to an amplifier usually consist of a set of RCA sockets. If you are lucky the head unit will provide RCA output connections which can be directly connected to the amplifier. In the majority of cases some kind of adapter will be required to reduce the output level of the head unit to a suitable value for the input of the amplifier.

Power Supply

The supply that the amplifier is connected to is vital to ensure a pure clean sound. To get the optimum sound the supply cables should be routed directly to the battery ideally keeping the cables as far from the other cables as possible. This is to prevent any spurious 'noise' being picked up which will manifest itself as buzzes, hums and clicks on the audio from the amplifier.

The amplifier itself is switched on and off by connecting the supply usually used for an electric aerial straight to the remote input of the amplifier.

If buzzes, clicks and hums are present on the audio then a choke can be placed in series with the power supply lines which will reduce and hopefully eliminate it.


The final point that shouldn't be overlooked is the location of the amplifier. The amplifier must be located in a position where it has good airflow to ensure that it doesn't overheat. In the event of overheating the amplifier will probably shutdown or at worst it will fail.

It should also be located somewhere where it will not be exposed to electromagnetic radiation such as too close to the engine etc.

An good quality sound system will make an excellent addition to any modified cars.