Guitar Amplifier 101

A guitar amplifier is a device that amplifies the signal. In other words, it strengthens the audio signal that comes from a source such as electric, acoustic or bass guitar. Altered signal is then expressed through a loudspeaker which is typically cased in a metal or wooden cabinet. Usually,  built in into guitar amplifier devices further modify the signal. Some of these are equalizers that modify the tone of the signal by emphasizing or de-emphasizing certain frequencies as well as a variety of different dynamic, distortion and reverb effects.

 

In the beginning

 

The birth of amplifiers draws its origins to the telephone and radio broadcast industry back in 1910`s. It was not until 1930 that the first practical electric guitar and amplifier took form. Electro String Instrument Company developed these amplifiers. Shortly after other companies like National, Dobro, Gibson, and Rowe- DeArmond presented their versions of guitar amplifiers that found wide commercial use among consumers. Further development of guitar amplifiers was shortly stopped by WW2. However, in the late 1940`s many new companies and individuals began to make amplifiers.

In 1947 Leo Fender founded his Fender Musical Instrument Company. Fender amplifiers became known for their ruggedness and power so they quickly became dominant on the market. Moving forward in time with the birth of Rock & Roll demand for bigger and louder sound and sound systems got emphasized so new and better solutions of guitar amplifiers came to light. This was the time when the tube and solid state-based amplifiers were born.

 

Guitar Amplifier Structure

 

The usual structure of the guitar amps consists of, most commonly, two amplifier circuit stages with an addition of the circuits for tone shaping. Furthermore, more expensive amplifiers can contain additional control for more frequency ranges, such as mid-range frequency controls and “ presence “ control for the high-frequency range of the signal. When it comes to the configuration of the guitar amplifiers there are usually two options. First, combination or combo, which incorporates an amplifier and one or more speakers in the cabinet. The other type is a standalone amplifier – “amp head“. In this case, the speaker is not included. The signal is passing the amplifier via speaker cable to one or more external speaker cabinets. Speaker configurations in cabinets come in a wide variety, ranging from cabinets with a single speaker ( 1*10, 1*12 ) to multiple speakers ( 2*10. 4*10. 12.10 ).

 

Vacuum Tube

 

Vacuum Tube amplifiers were dominating the market until 1970`s when Solid State based types took over. One of the main reasons is that tube components in amplifiers overheat quite easily. Therefore they get useless over time. On the other hand, the sound of tube amplifiers delivers more a natural and “warm“ sound so audio enthusiasts still use them today.

 

Solid Slate Amp

 

Solid State amplifiers consist of semiconductor (Solid State) circuits. They are considerably less expensive and more reliable from the tube amplifiers. Some Jazz guitarists are preferring this type of amplifiers since they produce much “cleaner sound”. They are also varying in output power, size, price and sound quality.

 

Modeling Amp

 

Modeling amplifiers use the microprocessor technology that allows the use of digital onboard effects in guitar amps to create numerous different sounds and tones that simulate the sound of a range of tube amplifiers and different sized speaker cabinets, all using the same amplifier and speaker. They can be programmed to simulate the characteristics of the tones of the variety of amplifier models as well as speaker cabinets and even the different microphone placements. 

 

Additional Resources & Source Texts

 

https://books.google.rs/books?id=9Jn1DAAAQBAJ&printsec=frontcover&dq=guitar+amplifiers&hl=sr&sa=X&ved=0ahUKEwjF5cPitZ_WAhXJAsAKHVJvCnIQ6AEIJjAA#v=onepage&q=guitar%20amplifiers&f=false