Reproducing low frequencies also requires a suitable in a single unit which is typically housed in a rectangular wooden box.The amplifier head or "amp head" contains the electronic circuitry constituting the preamp, built-in effects processing, and the power amplifier.
produced distortion effects by connecting the already distorted output of one amplifier into the input of another.
Later, most guitar amps were provided with preamplifier distortion controls, and "fuzz boxes" and other effects units were engineered to safely and reliably produce these sounds.
In the 2000s, overdrive and distortion has become an integral part of many styles of electric guitar playing, ranging from , but other instruments produce a wider frequency range and need a suitable amplifier and full-range speaker system.
Much more amplifier power is required to reproduce low-frequency sound, especially at high volume.
The preamplifier is a voltage amplifier that amplifies the guitar signal to a level that can drive the power stage: the signal is made larger, but without significantly increasing its energy content.
There may be one or more tone stages which affect the character of the guitar signal: before the preamp stage (as in the case of guitar pedals), in between the preamp and power stages (as in the cases of effects loop or many dedicated amplifier tone circuits), in between multiple stacked preamp stages, or in feedback loops from a post-preamp signal to an earlier pre-preamp signal (as in the case of presence modifier circuits).
The tone stages may also have electronic effects such as There are two configurations of guitar amplifiers: combination ("combo") amplifiers, which include an amplifier and one or more speakers in a wooden cabinet; and the standalone amplifier (often called a "head" or "amp head"), which does not include a speaker, but rather passes the signal to a or "cab".
Guitar amplifiers range in price and quality from small, low-powered practice amplifiers, designed for students, which sell for less than USD, to expensive amplifiers which are custom-made for professional musicians and can cost thousands of dollars.
Players use the line out to connect one guitar amplifier to another amplifier in order to create different tone colors or sound effects.
However, in most styles of rock and blues guitar the line out is not used to connect the guitar amp to a PA system or recording console because the tonal coloration and overdrive from the amplifier and speaker is considered an important part of the amplifier's sound.
In the "amp head" form, the amplifier head is separate from the speakers, and joined to them by speaker cables.