Understanding Vacuum Tube Guitar Amplifiers - DVD By Gerald Weber Kendrick Amplifiers President, Gerald Weber, has overhauled and serviced over 15,000 vacuum tube guitar amplifiers, designed dozens of new model amplifiers and has produced thousands of boutique tube guitar amplifiers. This DVD will transform your experience of tube guitar amplifiers forever. Whether you are a beginner or a seasoned pro, you will never see tube guitar amplifiers the same again. Covers: AC and DC Voltage AC and DC current Resistance Capacitance Capacitive Reactance and how this affects frequency respsonse