Guitar Amplifier

The first electronic instrument amplifiers were designed for use with electric guitars. The earliest examples appeared in the early 1930s, after the introduction of electrolytic capacitors and rectifier tubes made economical built-in DC power supplies that could be plugged into wall sockets, thus freeing portable vacuum tube amplification equipment from its earlier dependence on heavy multiple battery packs for power. While guitar amplifiers from the beginning were used to amplify acoustic guitar, electronic amplification of guitar was first widely popularized by the 1930s and 1940s craze for Hawaiian music, which extensively employed the amplified lap steel Hawaiian guitar.

Tone controls on early guitar amplifiers were very simple and provided a great deal of treble boost but the controls, the loudspeakers used and the low power of the amplifiers (typically 15 watts or less prior to the mid-1950s) had poor high treble and bass response. Some better models also provided effects such as spring reverb and/or an electronic tremolo unit. Early Fender amps labeled tremolo as "vibrato" and labeled the vibrato arm of the Stratocaster guitar as a "tremolo bar"; see vibrato unit, electric guitar, and tremolo).

In the 1960s, guitarists experimented with distortion produced by deliberately overloading (or overdriving) their amplifiers. The Kinks guitarist Dave Davies produced early distortion effects by connecting the output of one amplifier into the input of another, an abuse that the designers could never have imagined. 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. Today, distortion has become an integral part of many styles of electric guitar playing.

Guitar amplifiers were at first used with bass guitars and electronic keyboards, but when broader-bandwidth sounds are needed, other instruments use a suitable full-range speaker system and different power level. Much more amplifier power is required to clearly reproduce low-frequency pitches produced by bass guitars and electronic keyboards, especially at high volumes. Reproducing low-frequency pitches also requires a woofer or subwoofer capable of handling low frequencies and a speaker cabinet that is designed for low-frequency reproduction. Such speaker cabinets need to be larger and more sturdily built than speaker cabinets for mid-range or high-frequency sounds.