How Does A Car Amplifier Work


In a car audio system, electronic transistors generally enhance the audio stream. An amplifier boosts an inaudible line-level signal from your head unit using electrical components like capacitors and resistors, so it’s powerful enough to drive a speaker’s cone back and forth to generate sound.

Every sort of automotive audio system will benefit from an amplifier, which will make the music coming out of the speakers louder and clearer and allow the system to hop levels quicker. But how do they work? Well, this article is all about the principle of the amplifier and its working.

What is a Car Amplifier?

A simple power amplifier accepts a low-power audio source as input and produces a high-power output signal. This amplification method is used in various applications where an electric signal is transformed into an auditory signal. Audio amplifiers are a type of amplifier.

The audio amplifier can be found at the input and output of any circuit that processes audio signals, such as in automotive.

Working Principle Of Car Amplifier

A vehicle amplifier features big output transistors that can handle a lot of currents. These are driven by the switching power supply and are provided by it. These signals drive more significant, powerful transistors from the more excellent power supply’s output to the speaker.

Because they frequently transform a small input voltage into a considerably greater output voltage, the Small Signal Amplifier is commonly referred to as a “Voltage” amplifier. The basic concept of the power amplifier is to transform the DC power obtained from the power source into an AC voltage signal that is given to the load.

How Does Car Amplifier Works

There are various steps involved in working for the car amplifier, starting with the power supply. The internal amplifier circuitry in car amplifiers is powered by a unique sort of internal power source. After that, these parts enhance and transmit a conditioned audio signal (supplied by a stereo) to the speaker terminals.

The following parts are found in almost every common vehicle amplifier today:

  1. A DC-DC power supply.
  2. Sound circuitry
  3. Switching circuitry for speakers
  4. Circuitry for bridging gaps
  5. Speaker level input stages


High-power transistors run the transformer at a fast pace (many thousands of times per second). The SMPS chip regulates how quickly the transistor turns on and off in response to power demands. On the other side of the +12V power supply, the transformer employs magnetic fields to output a higher voltage supply.

Even though they are powered by the vehicle’s batteries but it is not possible for the car amplifier to run speakers directly with high power from only 12 volts.

It is because of the mathematical characteristics of electrical power and speaker impedance (resistance). Ohm’s law is a fundamental guideline for determining things like the amount of energy given to a speaker dependant on the voltage supplied.


The switch-mode power supply in the vehicle amplifier (SMPS) It’s the most crucial component of the amplifier. It’s a critical part that’s required to acquire great power from a single 12V source.

Like those in automobile amplifiers, step-up switching supplies may take a lower voltage and multiply it multiple times to produce a more excellent value. Thousands of times per second, an integrated switching circuit (IC) chip turns high-current transistors on and off.

They alternate between enabling and disabling the transformer’s +12V supply. As a result, the transformer produces greater voltages on its output, dependent on the number of turns of copper wire on it.

The switching power supply of a vehicle amplifier rapidly flips the high-current transformer on and off thousands of times per second. In alternate cycles, two sides (+12V input connection) are switched on and off.

Surprisingly, it generates both positive and negative voltages! Amplifiers in automobiles may consume a lot of electricity. Many may easily take up to 50A (amperes), although that is generally only when the power is near its maximum. They barely draw a few amps during regular, low-volume operation.

The positive wire of an amplifier is usually linked to the vehicle’s battery via a fuse. Typically, the ground (negative) wire is attached to a clean metal connection on the body.

How To Switch On And Off Vehicle Amplifiers

A “remote on” cable is used to prevent the amplifier from remaining on when you are not using it. It is usually connected to a particular cable on your stereo. It can also be linked to an ignition wire shut off when the switch is turned off in the accessory position.

When the remote wire reaches 0 volts, the SMPS chip is turned off. It stops running as a result of this. The amp won’t use any of your battery’s power after that.

Three Stages

The input stage board comprises several smaller circuits that provide crossover functions, allow for greater power bridging, gain control, and prevent ground loop noise.

They take the audio signal from the input stage board, enhance it with the power supply’s output, and output it loudly.

Stages Of The Input

The input stages have a variety of tasks to complete. These are the ones:

  • Allow the amp to be connected to stereos that don’t have RCA connectors (speaker-level inputs)
  • Stop the dreadful “ground loop” noise from becoming magnified.
  • Provide both a high-pass and a low-pass crossover option.
  • Allows you to change the amp’s gain (or amplification level).

The input stages comprise an electrical component known as an op-amp, which is highly flexible (operational amplifier). Op-amps are tiny amplifier circuits integrated into a small chip and utilized in various applications.

Stages Of Amplification And The Output Section

The last steps between the original input audio signal and the new, amplified output signal are held in an amplifier’s amplification stages and output section. Car amplifiers feature bigger output transistors built for higher currents to meet the requirement of extra power.

The SMPS feeds these transistors, which then transfer the bigger, higher-power output signal to your speakers.

What Are Amp Channels?

Amplifiers are available in several configurations, the most popular of which are two-channel and four-channel amps. When choosing an amplifier, it’s critical to understand what this implies so you obtain the proper equipment for your project.

The pathways your audio stream will follow to generate an output signal are essential since they are channels. These channels in stereo determine the sound that emanates from the left and right speakers.

Some stereos also include forward and back outputs, allowing for a more immersive surround-sound experience. It’s critical to match the number of channels to the demands of your system to ensure you receive the sound quality and variety you want.

Using An Amplifier As A Bridge

When you bridge an amplifier, you connect the positive from one channel and the negative from another channel to a speaker. It effectively doubles the speaker’s power output (watts).

It is useful if your existing amp is being utilized to drive a larger speaker. It avoids the need to purchase a new amp, or if you are short on room yet want a more powerful, huge speaker.


A vehicle amplifier amplifies the tiny signal from your car audio, allowing you to use larger, more powerful speakers. It helps “filter noise” and improve the music quality coming from your speakers.

Moreover, Car amplifiers include various channels or outputs that may be utilized in “bridged mode” to power very big, powerful speakers like subwoofers. However, one should be very careful before selecting an amplifier and consider certain factors that fulfill their requirements.

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