Editing Instrument amplifier (section)

==Amplifier technology ==
Instrument amplifiers may be based on [[thermionic]] (tube or valve) or [[solid state (electronics)|solid state]] (transistor) technology.

===Tube amplifiers===

Vacuum tubes were the dominant active electronic components in amplifiers from the 1930s through the early 1970s, and tube amplifiers remain preferred by many musicians and [[record producer|producers]]. Some musicians feel that tube amplifiers produce a warmer or more natural sound than solid state units, and a more pleasing [[distortion (music)|overdrive]] sound when overdriven. However, these subjective assessments of the attributes of tube amplifiers' sound qualities are the subject of ongoing debate. Tube amps are more fragile, require more maintenance, and are usually more expensive than solid-state amps.

Tube amplifiers produce more heat than solid-state amplifiers, but few manufacturers of these units include cooling fans in the chassis. While tube amplifiers do need to attain a proper [[operating temperature]], if the temperature goes above this operating temperature, it may shorten the tubes' lifespan and lead to tonal inconsistencies.<ref>[https://web.archive.org/web/20061019054109/http://www.chitown.com/http/music/Musictips.html ''Cool it, man''; Michael "Mac" McCullough.]</ref>
[[Image:Trace Elliot Bonneville rear view.jpg|thumb  |A [[Trace Elliot]] Bonneville tube amplifier as seen from the rear view: note the vacuum tubes extending into the wooden cabinet.]]

===Solid-state amplifiers===

By the 1960s and 1970s, semiconductor transistor-based amplifiers began to become more popular because they are less expensive, more resistant to bumps during transportation, lighter-weight, and require less maintenance. In some cases, tube and solid-state technologies are used together in amplifiers. A common setup is the use of a tube preamplifier with a solid-state power amplifier. There are also an increasing range of products that use [[digital signal processing]] and digital [[Amplifier modeling|modeling]] technology to simulate many different combinations of amp and cabinets. 

The output transistors of solid-state amplifiers can be passively cooled by using metal fins called heatsinks to radiate away the heat. For high-wattage amplifiers (over 800 watts), a fan is often used to move air across internal heatsinks.<ref>[http://www.yorkville.com/default.asp?p1=6&p2=17&p_id=25 Power Amplifiers - General Information: Yorkville Sound] {{webarchive|url=https://web.archive.org/web/20101007213736/http://www.yorkville.com/default.asp?p1=6&p2=17&p_id=25 |date=2010-10-07 }}</ref>
===Hybrid===
The most common hybrid amp design is to use a tube preamp with a solid-state [[power amplifier]]. This gives users the pleasing preamp and overdrive tone of a tube amp with the lowered cost, maintenance and weight of a solid-state power amp.