Power Amplifiers – Meaning, Types & Best Tips to Buy Power Amplifiers

What are power amplifiers? Which audio power amplifiers to buy? Which specifications to consider when purchasing a power amp? What are watts and impedance? 

When choosing an amplifier, these are the questions that are most pertinent. 

This extensive resource will answer these questions and help you in your next amp purchase!

Introduction to Power Amplifiers

The most common question is, what is a power amplifier?

It is a device that sits between a sound source and a passive loudspeaker. It takes a line-level signal and makes it loud enough to fill a room or a venue with sound. It provides a constant high-voltage output minus any fluctuations in impedance or frequency response. 

Any system that utilizes speakers to produce sound will require a power amplifier. 

Why do you need a Power Amplifier?

An amplifier is one of the main components needed to connect music and the audience. It makes small signals bigger.

Whether it is a power amplifier for speakers or a professional power amplifier, the power amplifier is a device that amplifies the sound of the instrument and it enhances the overall performance of sound systems, including a home audio system in diverse situations. 

Power amplifiers are feature-packed with one, two, or more channels. A mono power amp would have one channel, and a stereo power amp would have two channels.

A standard feature on most power amplifiers is a power switch, which engages the device, and volume control to determine the device’s output level.  

6 Types of Power Amplifiers 

It’s noteworthy to mention that depending on the type of output device that is connected, there can be Audio Power Amplifiers, Radio Frequency Power Amplifiers or DC Power Amplifiers.

Power amplifiers can be broadly categorised into these main types:

  1. Digital Power Amplifier

These are used in amplifying the power of pulse width modulated signals and they can be seen in power electronic components such as motor drives. They amplify the input signal which comes through the microcontroller system and feed the amplified signal to the DC motor.

The analog signal in the digital power amplifiers is encoded in a pulse train and it is restored at the output using a bandpass filter. Digital power amplifiers are mostly used in audio frequency applications and they are also seen in microwave frequencies.

  1. MOSFET Power Amplifier

MOSFET transistors are also known as Metal Oxide Semiconductor Field Effect transistors and are used in applications with small signal linear amplification. Here the magnitude of the input impedance is very large and gets easily biased. To develop a linear amplification, the MOSFET needs to be operated in its saturation region and it has to be operated biased around a centralized constant Q point.

  1. Microwave Power Amplifier

These power amplifiers consist of active elements with passive transmission line circuits for critical functioning in microwave-related systems and designs. Microwave power amplifiers are used in applications such as antennas, limiter diodes, MMIC-based power amplifiers, etc.

  1. Transistor Power Amplifier

In this power amplifier, a power transistor is used to amplify the signal. Tape recorders, public address systems, radio and television receivers and other electronic devices use transistor power amplifiers in their circuit design.

  1. High-Power Amplifier

This is mainly a nonlinear device used to amplify a small signal to a higher level. A high-power amplifier is used in applications with high-power output.

  1. Multichannel Power Amplifier

A multichannel power amplifier produces copies of the same input signal with the same values distributed over multiple output channels.

Top 7 Things to Consider While Buying a Power Amplifier

When choosing a power amplifier, do not miss out on these specifications as the power amplifier is critical to the quality of the sound system.

  • Connections/Inputs: Make sure you have enough best-quality inputs for everything you’re plugging in.
  • Power output: It equates to how loud you can pump out music. You would need more power if your room or speakers are big-sized. Also, consider speaker sensitivity.
  • Total Harmonic Distortion + Noise (THD + N): It measures how much effect the amplifier has on the sound output.
  • SNR (Signal to Noise Ratio): To make you hear more of the music and less of the noise, consider the signal-to-noise ratio. Choose a product that has a strong signal-to-noise ratio.
  • Headroom: It is the difference between the normal operating level of an amplifier and the maximum amount that an amplifier can pass without distortion. For the speakers to produce a clean and undistorted signal, it would be a good idea to use an amplifier with extra headroom.
  • Impedance: It determines the compatibility between an amplifier and a set of speakers.
  • Consider the amplifier class: Class A design is the least efficient but has the highest sound fidelity. Class B design is a little more efficient but has a lot of distortion. Class AB design packs a punch with power efficiency and superb sound. Class D design offers the highest efficiency but isn’t quite as high-fidelity.

A Final Word on Power Amplifiers

Looking for a high-power amplifier price in India? 

We are assuming if you have read so far, you must have already braced yourself to explore our carefully curated collection of power amplifiers. Also, we understand there is a lot to keep in mind when buying power amplifiers and if It’s not a task you want to take up single-handedly, we are here to help! 

Head on over to check out our best power amplifier brands and reach out to our experts so they can help you determine which power amplifier will best suit your needs.


  1. How many Watts do I need in a power amplifier?

Power amplifiers are rated in watts. 

For home use, your amp should be approximately 20W. For a venue that holds around 100 people with a live performance or gig (small-scale live event), a 20W tube amp, or a 40W solid-state amp would be appropriate.

The higher the power (watts), the louder and cleaner the speakers will play. Ultimately, it all depends on your listening habits and your speaker’s efficiency.

  1. Why should I buy a power amplifier?

Power amplifiers are widely used in audio applications, radio communication, car audio, live venues, and medical equipment (MRI) among several others. 

For most people, it amplifies the sound of the instrument and boosts the overall performance of all kinds of sound systems, including a home audio system in many situations. Plenty of audio systems require power amplifiers and if chosen well, they will serve you for many years to come. 

Also, in common parlance, the receiver and amplifier might as well mean the same thing. However, they are not. There are subtle differences between the two. This guide by Ooberpad helps you understand the main differences between the two.

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