| 摘要 |
PURPOSE:To prevent effectively click sounds caused by the inter-pole capacity of a semiconductor switch, by providing a capacity between the in-phase input and the inverse input of an operational amplifier to constitute a path circuit for the click sounds. CONSTITUTION:A resistance network 2 and a switch means 3 are provided as conventional. However, an inverse input terminal A of an operational amplifier 16 is connected to an in-phase input terminal B via a capacitor 20 of small capacity and at the same time grounded via a resistance 21 of small resistance. Therefore, the time constants of capacitor 20 and resistance 21 are sufficiently small to the audio signal. Thus a differentiating circuit is constituted to click sounds without giving any effect to the audio signal to give an application to the in-phase input of the amplifier 16. Then, it is possible to reduce the amplitude of click sounds of an output owing to the in-phase eliminating effect of the amplifier 16. |
