Fact Checked

What is a Stereo Amplifier?

Keith Koons
Keith Koons

A stereo amplifier is a device that increases an audio signal so that it can be heard through a speaker. While this would seem like a basic function of any audio equipment, the power required to produce a series of sounds hardly takes any energy at all. Without an amplifier, the music from a radio may sound like a distant whisper that many humans would not be able to hear at all. To generate that sound through a speaker, a much greater source of power is required, and that sudden surge of power is likely to distort the acoustics that are produced. A stereo amplifier increases both the power generated towards the output and the quality of the sound being replicated at the same time, allowing consumers to comfortably hear music or any recorded audio through speakers.

The logistics behind a stereo amplifier are actually quite a bit more complex than the standard definition implies, because a number of things must happen at a precise time in order for the sound output to be sufficient. Since many amplifiers work off of an electrical power supply, which is an alternating current, the energy flowing into the device needs to be transformed into a direct current. While the transition would not be important within many electronic devices, a stereo amplifier requires an uninterrupted source of power in order to effectively power a speaker.

Man playing a guitar
Man playing a guitar

It is interesting to note that the faint whisper of sound coming from a record player or compact disk (CD) is not the actual sound that is heard by the listener. The stereo amplifier actually takes that incoming sound and converts it into a different format that is compatible with the power required by the speakers. Without this conversion, the noise provided by the speaker would be filled with static and other types of interference. That is why complex sound systems that implement large speakers require a powerful amplifier; without it, the quality would be compromised.

Stereo amplifiers are used within hundreds of common audio devices ranging from televisions and home theaters to CD and Move Picture Experts Group, Audio Layer 3 (MP3) players. Although the sound capacity and audio translation may vary greatly between these models, each of them would be worthless without a stereo amplifier. For example, many consumers will upgrade headphones for portable devices in hopes of achieving a richer audio experience, but it is often a weak stereo amplifier that is responsible for the poor quality.

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Discussion Comments


@allenJo - One thing that I look for in a mini stereo amplifier is simplicity of design and yet powerful signal boosting strength. The fact is that I’m not a sound engineer.

I don’t have the time to mess with a whole bunch of sliders and knobs to tweak a system and get just the kind of sound that I need. I’ve found some easy to use amplifiers however that even I can understand and yet deliver professional quality results.

You can often find these systems by reading online stereo amplifier reviews. You can find budget models that will deliver good performance over the long haul.


@everetra - One of the first radio signals I ever heard as a youngster had no amplification at all. I can vouch for what the article says; the sounds were faint whispers.

No, I am not referring to simple pocket radios. That sound quality is not bad actually. I am referring to a crystal radio set. It came with my first electronics set.

A crystal radio requires no electrical power at all. It uses crystal to tune into the radio signals in the air. You can hear the stations, but they are ever so faint. Still, it’s fun that you can do this without the need for electricity. But it does show you how important a power amp is in your audio system.


I am amazed at how a good audio amplifier can dramatically increase the power and output of an audio signal. This is not only true for stereo systems but even portable units as the article points out.

For years I owned an mp3 player that I used to listen to through little ear phones. One day I bought this device that claimed to broadcast “stereo surround sound” out from my mp3 player.

Honestly I was a little skeptical at first but decided to give it a try. That little unit is amazing! I honestly can’t tell the difference between the sound quality from that mini boom box adapter for my mp3 player and the sound coming from a full fledged stereo.

Okay, maybe the floor doesn’t shake like with a big home theater system, but other than that the sound is the same in my opinion.

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