Amp-Tone.ComAmp-Tone.Com» Pre-Amplifier Distortion http://amp-tone.com guitar amplifiers, tube amps, & solid state guitar amplifiers Fri, 04 Nov 2011 19:47:05 +0000 en hourly 1 http://wordpress.org/?v=3.3.2 Pre-Amplifier Distortion http://amp-tone.com/vacuum-tubes-for-guitar-amplifiers/pre-amplifier-distortion/ http://amp-tone.com/vacuum-tubes-for-guitar-amplifiers/pre-amplifier-distortion/#comments Mon, 05 Apr 2010 20:59:18 +0000 Nigel http://amp-tone.com/?p=38 The pre-amplifier section of a guitar amplifier serves to amplify a weak instrument signal to a level that can drive the power amplifier. It often also contains circuitry to shape the tone of the instrument, including equalization and gain controls. Often multiple cascading gain/clipping stages are employed to generate distortion. Because the first component in a valve amplifier is a valve gain stage, the output level of the preceding elements of the signal chain has a strong influence on the distortion created by that stage. The output level of the guitar’s pickups, the setting of the guitar’s volume knob, how hard the strings are plucked, and the use of volume-boosting effects pedals can drive this stage harder and create more distortion.


Marshall MG4 Series MG100HFX 100W Guitar Amplifier Head Black

During the 1980s and 1990s, many amps featured a “master volume” control, essentially an adjustable attenuator between the preamp section and the power amp that conveniently enables the generation of high distortion levels in the guitar amp’s preamp section while diverting most of the resulting signal away from the power valves, keeping the output volume at manageable levels. However, this also results in the power valves being operated well within their linear region, reducing the distortion that they add to the output signal.

These “master volume” amps, when run with the master volume control on full and the preamp volume low—while creating much clean headroom—can result in very high volumes indeed if paired with an overdrive effect such as the Ibanez Tube Screamer.


Marshall MG4 Series MG100HFX 100W Guitar Amplifier Head Black

Solid-state gain/clipping stages are also employed in many amplifiers. Some amplifiers (notably the Marshall JCM900) utilize hybrid designs that employ both valve and solid-state components.

Marshall MG4 Series MG100HFX 100W Guitar Amplifier Head Black


Marshall MG4 Series MG100HFX 100W Guitar Amplifier Head Black

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