Amplifier

Amplifiers and their history

An electronic device that amplifies low-power electronic signals. The electronic signal originates from a source such as a guitar pickup or radio receiver, once it passes through the amplifier it is strong enough to drive large speakers or headphones. An amplifier can be found in all sorts of sound systems including home audio, car audio, at concerts and clubs. Amplifiers have multiple inputs in them, of course depending on the model, but sources can be anything from a turntable to a cassette player. The signal strength can be multiplied a few times over by an amplifier, depending on the requirement. A few hundred microwatt signal can be taken up to a few watts in consumer devices such as small speakers, or a few hundred watts in a home stereo system. In a club, it could increase the signal by a few hundred thousand watts to power all the speakers and subwoofers. Amplifiers are generally aimed at audiophiles.

Invented some time around 1912 by Lee Dee Forest, who was responsible for the base technology allowing amplification; the 'triode vacuum tube' or the 'Audion'. Which is why older style amplifiers are known as tube amplifiers. Interestingly, Lee Dee had a basic understanding of the functionality but this was the foundation technology for radio broadcasting, sound in movies, long-distance phone calls and many many other applications. Modern amplifiers make use of transistors instead of the vacuum tube.

Amplifier types

Till the 1970s amplifiers were mostly made using the vacuum tube. Once the Power MOSFET transistor came about in 1974, many major brands started using it in amplifier manufacturing. The smaller amplifiers that are included in other devices, such as radios, use fast-switching MOSFETs. These are the most simple kind, with basic audio quality. Today most amplifiers make use of transistors, although many audio engineers and musicians prefer the tube amplifiers; claiming that they produce a 'warmer' sound.

Tube amplifiers are a lot heavier, tend to heat up and require more maintenance. Also costing much more than the newer, transistor-based, amplifiers.

There are smaller amplifiers that are used to send out a better signal to headphones, making them punchier. Built for this specific purpose, to improve headphone signal recreation.

Comments

Amplifiers are available as stand-alone units that are at the centre of an audio system, such as a home sound system. They come with various power ratings that let one know how much power they can put out, generally the higher the rating the more power it can put out. Meaning it can make things louder.

The ones that are for home audio have multiple sound options, for instance, a mode for movies or a different one for listening to music. They also have EQing options in case one wants to manually change how the audio sounds. 

Available at many different prices given many brands produce amplifiers. The prices are from a higher point on the price spectrum. Known brands include Sonos, Sony, Yamaha, Kenwood, Pioneer, Onkyo and many more.