| 摘要 |
PURPOSE:To form an audio signal amplifier circuit capable of improving sound quality by effectively eliminating howling. CONSTITUTION:While the howling occurs and a howling detection signal is being outputted from a howling detecting means 30, a howling elimination filter means (LPF) 28 is operated, and the howling can be eliminated. After that, when the howling detection signal ends, the operation of the howling elimination filter means 28 is stopped, and also, the loop coupling degree (gain) of the circuit can be decreased sequentially by a loop coupling degree adjusting means (automatic attenuator) 32. When no howling detection signal is outputted again at a certain coupling degree, the loop coupling degree is fixed at that level. Therefore, the howling can be automatically eliminated. and the loop coupling degree of the circuit can be adjusted where no howling occurs again. |
