How do Audio Amplifiers Work

An amplifier is a device that accepts a weak electric current from a microphone or guitar pickup, then amplifies or strengthens it. An audio amplifier is an electronic circuit that receives an electrical signal and converts it into an amplified signal suitable for driving speakers. Learn how they work and more in this post!

Audio Amplifiers:

An audio amplifier is an electronic circuit that receives an electrical voltage and converts it into a higher voltage government with the help of other components such as transistors, resistors, capacitors etc.

It usually starts with input signals delivered by voice coils to get them amplified before connecting them to speakers which convert the amplified signal back to sound waves. Their basic purpose is to increase the power of the voice coil so that they can be more easily used for sound reproduction.

They are also used to filter noise from audio signals. For example, loudspeakers are driven by electric current while microphones are driven by voltage patterns. A microphone is said to be a voltage amplifier because it takes small electrical pressure fluctuations in voice coils and converts them into larger voltages on its output terminals.

Audio amplifiers are said to be current amplifiers because they take input voltage signals and convert them into larger currents on their output terminals.

History of Audio Amplifiers:

Amplifiers have been used since the 19th century and the first amplifier was patented in 1876. The original design of an amplifier was done by Thomas Edison and Emile Berliner by using a transformer and a condenser microphone to amplify the electrical signals of the voice coil of a loudspeaker.

In 1925, Louis Armstrong played his trumpet through an amplifying horn invented by Western Electric Company. In 1946, engineers at Bell Telephone Laboratories developed the first transistorised amplifier which later became known as transistorised amplifiers. They were more compact and affordable than tube amplifiers and had better performance, but they were more fragile and unreliable too.

Today, most modern amplifiers use solid state amplifiers and transistors and only a few people still use the older model.

How Audio Amplifiers work:

To better understand how an audio antenna amplifier works, let’s take a look at the components used in it one by one.

Amplifiers consists of two types of components: The input stage which takes inputs from an instrument; and the output stage which sends the amplified signal to speakers.

The more familiar terms of both stages are: Amplifier (input & output), Voltage amplifier (voltage amplifier), Current Amplifier (current amplifier). The voltage amplifiers use vacuum tubes while the current amplifiers use transistors.

Working of an Amplifier Circuit:

An audio amplifier works on the principle of negative feedback, which means that its output signal will be fed back to its input terminals in the opposite direction so that it can reduce the undesirable effects on it.

A basic amplifier circuit has an amplifying device or transducer at its output. When the input voltage is larger than the output voltage, then amplifying device will become forward-biased.

Basic Elements in an Amplifier Circuit:

Let’s take a look at the three basic elements in an amplifier circuit: output, input and power supply. These elements are as follows:

1. Output:

This is commonly used as a loudspeaker to convert the amplified signal into sound waves. The several circuit components make it work as follows: It consists of a speaker diaphragm or voice coil which acts like a magnet and picks up electrical signals from input terminals which help it to create vibrations and force out voice waves through air.

2. Input:

It is the source of the input signals which are used to make sounds. It comes in different types like microphones, phonograph decks, TV sets etc. It consists of elements like condenser microphones, transducers, contact pickups etc. The output of these elements is converted into electrical voltage or current patterns called signals.

3. Power supply:

It is also known as the supply voltage which helps the other elements in an amplifier circuit work properly. It provides power to all elements and creates an environment where they can work together. It consists of four basic elements: resistors, capacitors, inductors and transformers. It mainly consists of two parts: DC power supply and AC power supply.

4. Salient Features

It boosts the signal to a higher level so that it can be converted into sound waves. It is mainly used with power amplifiers. The output voltage of an audio amplifier is controlled to provide the desired level of clean sound. It has line, phono and headphone outputs so that it can deliver different kinds of audio signals to listeners which vary from low tones to very high tones.


These are some basic working of an audio amplifier. Audio amplifiers are built using different types of components which help control the flow of electrical current or voltage through them.

These include resistors, capacitors, drivers, transformers, power supplies etc. Each component plays a specific role in an amplifier circuit which helps amplify the signal and convert it into sound waves for us to hear. We have seen the basic working of an audio amplifier and how it works?


Q: What is the best home audio amplifier?

A: McGary Audio SA-1 ($3,985 USD) First Watt SIT-3 ($4,000 USD) Audio Hungary Qualiton APX 200 ($4,700 USD) Merrill Audio Thor monoblock amplifier ($4,800 USD) Odyssey Audio Kismet ($4,900 pair USD) Pass Labs XA25 ($4,900 USD) Linear Tube Audio ZOTL40 ($6,800 USD) McGary Audio SA-2 ($7,985 USD) Manley Labs Snapper monoblocks ($8,400 pair USD)

Q: How to test and measure audio amplifiers?

A: Audio Amplifier Testing. A typical high quality audio amplifier circuit. The circled figures indicate the points at which oscilloscope checks may be made and the order in which they should be carried out. AF amplifiers can be tested with an oscilloscope by making sequential stage checks, using a sine wave input.

Q: What is the function of an amplifier?

A: Following details from the upper picture: 1.Support to connect with computer by USB/RJ45 interface. … ITC Digital Amplifier Competitive Advantages: Independent research and development of new switching power supply+digital power amplifier technology. Power supply voltage protection function. … Intelligent peak clipping limiter. …

Q: Does a TV antenna amplifier really matter?

A: Studies have shown that trees have a dB loss of 0-10 dB within the UHF and VHF frequency. A TV antenna installed at a lower height can improve signal propagation since the signal can better avoid the tree canopy. In rare cases raising an antenna can degrade reception. Often in these cases, a dense tree canopy can be blamed.