| 摘要 |
PROBLEM TO BE SOLVED: To improve the durability of vacuum tubes, to improve the operability and to interface the amplifier with a digital peripheral equipment by using the vacuum tube amplifier for amplifying an audio signal and allowing a computer control section to conduct various control and protection operation or the like. SOLUTION: An audio signal received from an input terminal 11 is pre-amplified by using a vacuum tube 12, an equalizer amplifier 21 is used to provide a desired frequency characteristic to the signal and an electronic volume 22 adjusts a level to be a prescribed level. Furthermore, a vacuum tube 13 is used to amplify the resulting signal and the result is outputted via an output transformer 14. A microcomputer 23 controls the equalizer amplifier 21 and the electronic volume 22 through the input by an up-down switch 25 and a changeover switch 26 and a display result of a liquid crystal display section 24. The microcomputer 23 is provided with a self-diagnosis function such as detection of an overload and an overcurrent or the like. Moreover, the microcomputer 23 controls indication of voltage and current of each section, indication of sound volume and sound quality and display of a warming-up time and exchanges a digital signal with an external device via an external terminal 27. |
