• Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Street Smart Automotive Solutions

Whats in your ride?

  • Reviews
  • Audio
    • Apple CarPlay and Android Auto
    • Car Audio
    • Custom Fabrication
    • Sound Deadening
  • Accessories
    • Automotive Lighting
    • Marine Audio / Lighting
    • ATV Audio / Lighting
    • Window Tint
  • Convenience
    • Radar Detectors
    • Remote Starters
    • Security
  • Driver Safety
  • Gallery
  • About Us
    • Installation
    • Custom Installation
    • Why Choose Us
    • Meet the Team
    • Hours and Directions
    • Contact Us
  • Facebook
  • Instagram
You are here: Home / ARTICLES / How Does a Car Audio Amplifier Work – The Power Supply

How Does a Car Audio Amplifier Work – The Power Supply

December 19, 2021 By BestCarAudio.com Leave a Comment

Car Audio Amplifier

We’ve talked about car audio amplifier features and specifications at great length, but up to this point, we haven’t discussed how a car audio amplifier works. In this article, we’ll provide a simple overview of how the power supply in your mobile amplifier can take the 12 volts supplied by your electrical system and convert it into a much higher voltage to drive your speakers.

Making Power for Your Speakers

To supply enough power to your speakers to produce music at realistic listening levels, we need a lot of voltage. For standard 4-ohm speakers, it takes a peak-to-peak voltage of almost 60 volts to deliver about 100 watts to your speaker. In most amplifiers, this voltage is configured as +30V and -30V, relative to the ground reference voltage of your vehicle chassis. So, how in the world do we get plus and minus 30 volts from 12? That’s the job of the power supply.

Car Audio Amplifier
The positive and negative rail voltages of a modern car audio amplifier. In this case, we have +28.4V and -27.7V.

How a Transformer Works

Power supplies couldn’t be created with any reasonable amount of efficiency without a transformer. A transformer is a simple device that increases or decreases alternating current (AC) voltages using two coils of wire wrapped around a magnetically conductive iron core. If you have a 1:2 transformer and feed 12V of AC signal into the primary, you get 24 volts on the output. The big green boxes out on your curb or the cylinders on the power poles near your house are step-down transformers that convert the 16kV feed that enters your neighborhood into 120- and 240-volt feeds to your home.

Car Audio Amplifier
The toroidal power supply transformer in a good-quality car audio amplifier.

How Do We Get AC Voltage in a Car?

As you may (or should) know, the power supplied by the battery and alternators in our cars and trucks is direct current (DC). Left in that state and fed into a transformer, we’d see a small voltage spike when the signal was first connected, then nothing. The steady current flowing through the primary winding would simply heat it up and not produce anything on the output side of the transformer.

Car Audio Amplifier
The pulse-width modulated output signal from the power supply switching devices.

Since we need an AC signal, modern amplifiers use a pulse-width modulator to create a series of square waves that turn on a bank of MOSFETs (electrically controlled high-current switches) that pulse the supply voltage on and off very quickly. Many high-quality amplifiers have power supplies that switch at more than 300kHz.

Car Audio Amplifier
The power supply MOSFETs switch the 12V feed from our batteries and alternators on and off at high speeds to create an AC signal that feeds the transformer.

In the simplest of terms, by switching the connection from the battery to the input of the transformer on and off very quickly, we create an alternating current signal. The voltage of the pulsed signal is increased through the transformer and then fed into a set of diodes and capacitors to smooth it back out to what we call the rail voltage. The rails are the positive and negative power supply sections of the amp that are connected to the output devices.

In application, the circuit is far more complex, but this is the basic operation of the system.

Energy Storage and Power Delivery

As the output voltage of a car audio amp increases, so to does the amount of current flowing to the speaker. The pulse-width modulation controller that manages the power supply can change the relative “on” to “off” time in order to increase the current supplied by the amp. More “on” time means that more current is fed to the transformer, which results in more voltage being produced on the output. Regulated back down to the required rail voltage, this extra voltage ensures that we maintain stable rail voltages.

If you look inside an amp, you will almost always see a toroidal transformer and a bank of energy storage capacitors. These large capacitors help smooth the output of the transformer and diode rectifier stage, and store large amounts of energy so that the amp can keep up with the current demands of the audio signal.

Car Audio Amplifier
4,000 microfarads of energy storage on the output rails of our amplifier.

Learn How a Car Audio Amplifier Works

You should now have a basic understanding of how your car audio amp converts the 12V feed from your alternator into much higher voltages for the rails. In the next article, we’ll talk about the front end or input stage of a car audio amplifier and discuss crossovers, gain controls and the features and functions that make it easier for your installer to configure your car audio amplifier for optimum performance in your car or truck.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

About BestCarAudio.com

BestCarAudio.com is a showcase for the very best mobile electronics retailers in the world and a place to educate and inform interested consumers about existing and emerging technologies.

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Primary Sidebar

Recent Articles

DragonEye Radar Gun

How Does DragonEye ECCM Lidar Work?

Over the past few months, we’ve talked about how radar detectors and laser defense systems work. Now it’s time to talk … [Read More...]

USB Thumb Drive

Don’t Put All Your Songs in One Folder on Your USB Drive

With the rise in popularity of digital media files over the last decade, car audio enthusiasts find themselves being … [Read More...]

Laser Shifting

How Do Laser Shifter Systems Work?

Sold as a means of preventing police officers from measuring the speed of your vehicle, laser shifter systems are … [Read More...]

Footer

Contact Us

Address

Street Smart Automotive Solutions
5310 Lakeland Drive
Flowood, MS 39232
United States (US)
Phone: 601-919-1875
Email: shopstreetsmart@aol.com

Location


Get Directions to Street Smart Car Audio
  • Facebook
  • Instagram

Copyright © 2022 Street Smart Automotive Solutions · Privacy Policy · Website by 1sixty8 media, inc. · Log in