Car audio systems come standard with an amplifier, though some limited quality is expected from factory-installed equipment that is built into a car’s source unit. Car manufacturers typically don’t install the highest quality audio components in order to save on costs. Raising the volume too high can distort the sound quality, and this distortion is typically caused by the amplifier’s inability to push enough power to the speakers. One key improvement you can make to your system is to add or upgrade your car amplifier, but how many watts do you need? To minimize the risk of distortion, and find a better match for your system, consider these factors:

• Number of Channels
• Impedance Capability
• Power Output

Number of Channels

An amplifier’s channel is a discrete power source. Since power is distributed through channels, the number of speakers you plan to include in your car stereo system will determine how many channels your amp should have. For example, if you are only adding a subwoofer to your existing standard factory system, a one-channel (mono) amplifier will work fine.

There are also two, four, and five-channel amplifiers available that can give your system more versatility. A two-channel amplifier can power two coaxial speakers or component speakers at a given time with one speaker or speaker and tweeter per channel. You can also bridge the amp. This combines the power from both channels into a higher-powered single-channel. A 4-channel amp could drive four separate speakers, or two speakers (channel 1 and 2) along with a single subwoofer (channel 3 and 4 bridged). For your existing audio system, adding more speakers, such as an additional subwoofer or full-range speakers, a four-channel amplifier will serve you well.

There are no limits to the number of channels in a car audio setup. It is wholly determined by your specifications and the sound you want to produce. Once you know how you want your speakers and subwoofers arranged, you will know how many channels you will need in your amplifier. From there, it is a matter of getting the correct amplifier power rating that matches the speakers’ continuous power requirements.

Impedance Capability

When designing your car stereo system, it is best to start by selecting your speakers first. Once you have a list of speakers, you can consider the speaker load, or specific impedance of the speaker to ensure you get the proper amp designed to handle the Ohm load (impedance.) The more speakers you connect, the more effort that channel of the amp has to use when powering the speakers. You don’t want to overload the amp with too low of an impedance.

Power Output

How much power should an amplifier be able to provide, both as a whole and per channel? Getting the correct amount of power to your speakers is crucial for getting the best sound. You will need to know your speakers’ power range to start to help you choose your amplifier based on those specs.

Let’s use an analogy to make things simpler, think of your amplifier wattage as your car’s engine horsepower and the speakers as your car’s tires. Just because you have a car with 1,479 HP doesn’t mean it will always drive at 200 mph. It only does so if you push on the accelerator (aka volume knob). However, if you have tiny tires with poor treads on the car (aka speakers), hammering the accelerator on an engine (amp) with too much horsepower (watts) will probably cause the tires (speakers) to spin out and blow up. You also don’t want to under-power your speakers. Let’s continue with our analogy. If you have a car with wide, heavy racing tires (power-consuming speakers) and you have a go-kart engine under the hood, the engine will struggle trying to accelerate the wheels because it doesn’t have the power needed to spin the wheels.

• Too much amp power results in potentially fried speakers.
• Too little amp power can result in too low of output.

Ideally, your amp should be able to deliver enough power to equal the speaker’s continuous power rating. For example, if a speaker is rated at 50 watts continous power and you have one of these speakers on each channel, you’ll need the amplifier to produce up to 50 watts per channel (100 Watts total power). If a speaker has a power range of 25-50 watts, it can produce sound at its best quality at up to 50 watts. Try to find an amplifier with a top RMS output that is equal to that of the speaker. If you have two speakers with a different rating each, use the lower speaker’s power rating as your reference point.

Choosing Your Amplifier

After learning all of this, it’s time to get down to the bottom line: choosing an amplifier. Remember that you need to know the number of speakers and speaker load as a starting point. This gives you a good idea of the number of channels you will need your amp. Then, the continuous power range will provide you with an ideal amp wattage range to look for. If you have questions or want recommendations for a quality power amplifier, Rockford Fosgate provides high performance amplifiers and are happy to recommend the best car amplifier for your car, truck, or SUV.

Amplifier Links

• Find Car Audio Amplifiers for your audio system.
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• Rockford Fosgate Power Series Car Audio Amplifiers