Patent ID: 8766082

Claim:
An amplifier for guitar comprising: a push-pull amplifier having at least one pair of first and second electron emitting devices, each electron emitting device including an electron source element, an electron receiving element and an electron control element; a double-pole switch having a first and second position, and comprising a first segment and a second segment, wherein the second segment is connected to the control element of the first electron emitting device; a high-pass capacitor having a first and second terminal, wherein the first terminal is connected to the control element of the first electron emitting device, and the second terminal is connected to the first segment of the double-pole switch; and a variable attenuator having a third terminal, a fourth terminal, and a variable wiper element, wherein the variable wiper element is connected to the control element of the second electron emitting device, the third terminal is connected to the first segment of the double-pole switch, and the fourth terminal is connected to the second segment of the double pole switch; such that when the switch is in the first position, the first segment of the double-pole switch simultaneously couples the second terminal of the capacitor to the third terminal of the variable attenuator while the second segment decouples the fourth terminal of the variable attenuator from the control element of the first electron emitting device; and when the switch is in the second position, the second segment of the double-pole switch simultaneously couples the fourth terminal of the variable attenuator to the control element of the first electron emitting device while the first segment decouples the second terminal of the capacitor from the third terminal of the variable attenuator.