| 摘要 |
PURPOSE:To simplify the circuit constitution, by eliminating a relay by switching plural amplifiers with use of a change of level of the switch control signal. CONSTITUTION:Amplifiers 22A and 22B amplify plural input signals individually. A switching circuit 24 switches selectively each amplifier according to the level of the switch control signal. A switch control circuit 60 transmits the switch control signal. Thus the switch control signal is transmitted from the circuit 60, and the driving current is controlled for the circuit 24 plus amplifiers 22A and 22B basing on the level of the switch control signal. For instance, the amplifier 22A is switched to the amplifier 22B to ensure the working for either one of these amplifiers. Thus the reproduced output of a magnetic head 36B is amplified by the amplifier 22B and furthermore by middle-stage amplifiers 26 and 28 to be supplied to a tone control circuit 62 via a terminal 44. |
