| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a desirable vacuum tube main amplifier for an audio device of which a vacuum tube is exchangeable. <P>SOLUTION: One of different vacuum tubes such as 2A3, 300B, 50 is plugged into a socket 31 so as to be exchangeable as an output stage vacuum tube 3. A plurality of power circuits are provided for a heater power supply circuit 6, a plate power supply circuit 7 and a grid power supply circuit 8 depending on a vacuum tube to be used. An appropriate power supply circuit is chosen by relays 62, 73 and 83 which operate in response to a vacuum tube exchange switch 5 and connected to the output stage vacuum tube 3. <P>COPYRIGHT: (C)2012,JPO&INPIT |
