When Do You Need a Car Stereo Amplifier?

April 9, 2012

A stereo's built-in amplifier is no match for the sound quality you get from a separate amplifier unit. Learn more about car stereo amplifier benefits.

Car Stereo Amplifier

The addition of a car stereo amplifier can improve the experience of listening to music or other audio in your car. Understanding the benefits that an amplifier can provide will help you to determine whether it is something you should install in your car.


A loud engine, noisy air conditioning system and a high level of surrounding traffic can contribute to a situation where the volume of the stereo cannot compete. Accordingly, a car stereo amplifier will help increase the volume and ensure that the audio can be heard.


If you have a reliable car stereo but it is an older variety, it might not have the features that a more modern stereo does. Where this is the case, a car stereo amplifier can be used to rectify this problem. Installing one with features such as equalizers and signal processing negates the need to install a new car stereo to get the features you need.

Sound Quality

If the sound produced by your car stereo is often marred by interference, the quality can be improved with the use of an amplifier. Amplifiers can make use of several channels of output, the numbers of watts used for this purpose varying according to the brand chosen. Where the sound from the car stereo is often affected by distortion, an amplifier eliminates this. Increasing the bass will often be sufficient to improve the quality and an amplifier can help in this regard.


If you work on your car regularly and like to keep up to date with the latest equipment, a multichannel amplifier gives you greater flexibility in this regard. An amp with several channels gives you scope to add upgrades and extras. It is also possible to obtain a car stereo amplifier that combines several channels into one so that the sound is more powerful, which is the manner in which subwoofers are often driven.


When you want an increased level of quality for your car stereo, but are reluctant to use a significant amount of power, an amplifier can be obtained which makes use of power efficiently. Amplifiers are divided into different classes, the better the class, the higher the efficiency. An amp that is properly fitted will also ensure that the sound is concentrated within the car, rather than being heard at a high level by those outside the car.

Installing a Car Stereo Amplifier

Installing an amp is much more difficult than installing car speakers. If you're not comfortable with installing an amp yourself, have a professional do it. To ensure the best sound amplification, make sure that your speakers can handle the power that comes out of the amplifier.

  • Disconnect the battery wire. Disconnect the negative wire from the battery to stop any power in the electrical system. This is an important safety step.
  • Find or drill a hole in the firewall. A power wire needs to go to the amplifier through the car's firewall to the battery. There may be a factory hole or you could use an empty rubber grommet. If there is no empty grommet or factory hole then it is necessary to drill one. A pilot hole is recommended to ensure you know where the drill bit comes out and avoid drilling into anything important.
  • Run the wire. Run the wire from the interior of the car through the hole and to the battery. Avoid any moving engine parts and pinch points. An inline fuse holder is necessary. Connect this close to the battery. This protects the car because the wire from the battery to the fuse is unprotected, which could cause a short. Run the power wire under the carpet, kick panel and rocker panel. Connect the power wire to the amplifier or the power distribution block.
  • Install the remote turn on lead and RCA cable. Run the remote turn on lead wire and RCA Cables from the head unit to the amp mounting location. The process is very similar to the power wire. Run the RCA cable on the opposite side of the vehicle from the power wire. This wire carries the sound signal from the head unit to the amp. If this wire is too close to the power wire, it can cause noise through the speakers. Not all amplifiers have a remote turn on lead.
  • Run the speaker wires. Run the speaker wires from the speakers to the amplifier. Again, run the speaker wires alongside the RCA cables and avoid the power wire. There is much less of a chance that the speakers will pick up noise from the RCA cables. Connect the speaker wires to the amp with ring terminals or other connectors. The larger terminal on the speaker is for the positive wire and the smaller is for the negative wire.
  • Ground the system. There is a wire to ground the amplifier. Connect the amp negative terminal to the chassis. Basically any metal spot will work fine. Cover this connection with caulk or other protective material.
  • Mount the amp. Most of the time the amplifier will be mounted in the dash. Make sure there is plenty of room for the amp and that there is plenty of wire. Choose the spot for the amp first and then connect the wires. Once the wiring is in place and working properly, then completely secure the amp.