Editing Instrument amplifier (section)

====Hard rock and heavy metal====
[[File:MarshallStack Slayer.jpg|thumb|A 3×6 stack of mock [[Marshall Amplification|Marshall]] guitar cabinets for [[Jeff Hanneman]] of [[Slayer]]]]
Electric guitar amplifiers designed for [[heavy metal music|heavy metal]] are used to add an aggressive ''drive'', intensity, and ''edge'' to the guitar sound with distortion effects, preamplification boost controls (sometimes with multiple stages of preamps), and tone filters. While many of the most expensive, high-end models use 1950s-style [[tube amplifier]]s (even in the 2000s), there are also many models that use [[transistor]] amplifiers, or a mixture of the two technologies (i.e., a tube preamplifier with a transistor [[power amplifier]]). Amplifiers of this type, such as [[Marshall amplifiers]], are used in a range of the louder, heavier genres of rock, including hard rock, [[Heavy metal music|heavy metal]], and [[hardcore punk]]. This type of amplifier is available in a range of formats, ranging from small, self-contained combo amplifiers for rehearsal and warm-ups to heavy ''heads'' that are used with separate speaker cabinets—colloquially referred to as a ''stack''.

In the late 1960s and early 1970s, [[Public Address system|public address systems]] at rock concerts were used mainly for the vocals. As a result, to get a loud electric guitar sound, early [[Heavy metal music|heavy metal]] and rock-blues bands often used stacks of 4x12" Marshall speaker cabinets on the stage. In 1969, [[Jimi Hendrix]] used four stacks to create a powerful lead sound, and in the early 1970s by the band [[Blue Öyster Cult]] used an entire wall of Marshall Amplifiers to create a roaring [[wall of sound]] that projected massive volume and sonic power. In the 1980s, metal bands such as [[Slayer]] and [[Yngwie Malmsteen]] also used ''walls'' of over 20 Marshall cabinets. However, by the 1980s and 1990s, most of the sound at live concerts was produced by the [[sound reinforcement system]] rather than the onstage guitar amplifiers, so most of these cabinets were not connected to an amplifier. Instead, walls of speaker cabinets were used for aesthetic reasons. 

Amplifiers for harder, heavier genres often use valve amplifiers (known as tube amplifiers in North America) also. Valve amplifiers are perceived by musicians and fans to have a warmer tone than those of transistor amps, particularly when overdriven (turned up to the level that the amplifier starts to [[clipping (electronics)|clip]] or shear off the waveforms). Instead of abruptly clipping off the signal at cut-off and saturation levels, the signal is rounded off more smoothly. Vacuum tubes also exhibit different harmonic effects than transistors. In contrast to the tweed-style amplifiers, which use speakers in an open-backed cabinet, companies such as Marshall tend to use 12" speakers in a closed-back cabinet. These amplifiers usually allow users to switch between clean and distorted tones (or a [[rhythm guitar]]-style ''crunch'' tone and a sustained [[lead guitar|"lead"]] tone) with a foot-operated switch.

[[Image:Bassstack.jpg|thumb|left|100px|A 2 x 10" bass speaker cabinet stacked on top of a 15" cabinet, with separate bass amplifier head unit]]