Typically, feedback is achieved by dialing up the amplifier’s gain and holding the instrument near its speaker. John Schneider writes in The Contemporary Guitar that a feedback loop is composed of the following segments: “The string feeds the pickup, which feeds the amplifier, which drives the speaker, which causes the guitar body to vibrate, which drives the string, which feeds the pickup, and so on.” He continues by noting: “This loop of energy is self-perpetuating, and can be controlled by altering the energy put into any part of the closed system.”1