In audio terms, an amplifier, also known as a power amplifier or simply an amp, is an electronic device that increases (or amplifies) electronic audio signals for the source device and delivers it to the output such as speakers or headphones. The incoming signals have low power and rely on the amplifier to increase the signal so that it can be heard at a decent volume.
The more powerful the amplifier, the louder the audio it can produce. That is, provided you have speakers that are equally matched.
The Evolution of the Amplifier
Before the invention of the amplifier, early phonographs or gramophones were mechanical devices. They relied on a vibrating diaphragm and sound was “amplified” by a large flaring horn. I am sure you can picture the classic “His Master’s Voice” logo.
Naturally, the quality and volume were poor by modern standards but thanks to the 1877 invention by Thomas Edison as well as improvements made by Alexander Graham Bell and others, it was great at the time. They are now prized as collector’s items.
Fortunately, things have come a long way since then.
Credit for the invention of the first amplifier goes to Lee De Forest for his 1906 invention of the triode vacuum tube amplifier. The invention also allowed for the rise of the AM radio. Variations of the vacuum tube amplifier design remained popular through to the 1970s. They are still preferred by many musicians, audiophiles, and hobbyists.
Silicon transistor amplifiers started to take over from valve amplifiers in the 1970s. Semiconductors were used in transistor amps to change the voltage and deliver audio. They used less power, were a lot more compact, and produced less audio distortion. Over time, the price of transistors dropped sharply which only boosted their popularity as the amp of choice for most people.
Development did not stop there and most modern amps make use of a solid-state design. Some incorporate a combination of modern metals and other materials for improved performance.
Sometimes, Height Speakers are the answer.
Amplifier setup options
A standard setup will consist of the input device or devices, an amplifier, and the speakers. Each amplifier has a peak output that will determine the volume. This is known as an integrated amplifier.
Other systems use a pre-amp or pre-amplifier to boost the volume before sending it to the main or power amplifier. This will increase the volume. Another option is to connect multiple amps in a chain formation to increase the output.
Unless you plan to include a receiver (see below) you want to consider the number and type of inputs and outputs are available on the amplifier. This will determine what type and how many devices can be connected to the system. You do not want to be limited. If you have multiple devices or a home theater or surround-sound system, you should consider a receiver to allow the connection and control of multiple input devices and speakers.
You want to ensure that the amp has enough power for your requirements as well as the size of the space on which it will be used.
There are two main power measurements to consider:
RMS stands for root mean square and defines the continuous power the amp can deliver. If an amp exceeds its RMS it will produce distortion. It could also cause heat and damage to the unit. This is the most important power rating to consider when comparing amps.
Less important, but worth noting, is the peak power. This refers to the maximum power the amp can deliver for short periods when necessary.
Remember that the power figures quoted by manufacturers are important indicators but will depend on the build quality and materials used. Inferior amps might be able to produce high power in theory but the audio quality will suffer when you try to take advantage of the top-end of the power rating.
Amps vs Receivers
Many people confuse these terms. The purpose of an amplifier is to increase the input signal to deliver louder music with minimal distortion. A simple amplifier and speakers set is fine if you are simply using one input device. When all we had was a turntable this was fine. Things are a bit more complex now.
Basic receivers are simply amps with a radio tuner and a minimum of two channels. As we connect more devices to our systems the need for more advanced receivers grew.
Most systems are able to handle multiple audio and video inputs. In order to control and manage this, an AV receiver is needed. They also typically contain a radio tuner. More modern receivers will allow for satellite radio or HD radio, both of which are becoming extremely popular.
It has the ability to decode a range of formats including digital signals. The typical traditional amplifiers can only work with analog inputs. They also feature multiple channels allowing you to connect additional speakers such as you would find in a home theater or surround-sound system.
A good receiver acts as the user interface and usually incorporates a remote control as well as a display. This will add to your convenience and enjoyment. Controlling multiple sources and devices can be confusing and complicated. A receiver makes this a breeze.
AC vs. DC Amplifiers
Most people are familiar with the terms AC and DC as they refer to electricity. While we might not all fully understand the difference, it is important to note that when it comes to amplifiers the acronyms have a slightly different meaning. There are, however, some similarities in how they deliver voltage.
To clarify the terms, AC refers to alternating current while DC is direct current. Most of the audio equipment you use at home will rely on DC.
DC amplifiers deliver a steady consistent voltage to amplify the incoming audio. They excel at low frequencies. AC amplifiers are better at rejecting noise. AC amps are becoming less popular as other technologies assist in creating better audio output.
The best amp in the world is useless without quality speakers that are able to handle the volume and deliver quality sound that is crisp and without distortion.
The amplifier is the powerhouse of your audio system and without a quality amp, you will never get the performance you want or expect. While all components are important, invest in a quality amp that will give you the power and quality you need for your audio enjoyment.
This article was last updated on September 8, 2021 .