Distortion is an audio phenomenon caused when the input signal is too high for the output device. In most audio applications, distortion is undesirable and audiophiles go to great lengths to rid their audio setup of distortion-creating characteristics. However, for guitarists distortion can be a source of great joy. The crunch that distortion gives to your guitar sound adds character and attitude to your tone. Distortion pedals alter the signal from your guitar in order to emulate the desirable characteristics of distortion. If you don’t have a pedal, you can create natural distortion using the controls on your amp.
Turn off your amp and turn down the master volume.
Turn the gain and any individual channel volume dials to 10.
Turn the volume dial on your guitar up to the maximum.
Select the bridge pickup with your guitar’s pickup selector switch. Move it to the farthest notch.
Turn the amplifier on and begin playing the bottom E string with your pick.
Increase the master volume gradually until you hear a crackling or crunching sound. This is caused by the power amp section as it works hard to achieve the output demands put on it by the settings. If you have a tube amplifier, the tubes will heat up as you increase the volume. This creates a very pleasant tube-overdrive tone. If you have a non-tube, or “solid-state” amp, you’ll notice the distortion is a lot harsher sounding.
Set the master volume to zero.
Turn the amp on and gradually increase the master volume dial. Two is typically a perfectly adequate volume level but adjust it to your own preference. If you have a powerful amp, you’ll rarely need to exceed a volume of 1 at home.
Engage the distortion setting. Some amps have on-board distortion. On modelling amplifiers, such as the Line 6 Spider, the amp uses circuitry to emulate distortion in the same way an effects pedal does. In tube amps, the distortion setting is typically labeled as “Crunch,” “Drive” or “Boost.” In such cases, the amplifier creates distortion by limiting the amount of voltage it delivers to the tubes. This forces the tubes to work harder to achieve the selected volume, causing them to heat up rapidly, causing distortion.
If your amp has multiple channels, the first is typically the most likely to create distortion. For example, channel 1 on the Fender Reverb amp is 6 db more powerful than channel 2. The bridge pickup is the most suitable for creating distortion because the tension of the strings increases in proportion with proximity to the bridge. The more tension there is, the louder the string when struck. The pickup at the bridge position therefore outputs a higher signal.