In audio, a very low frequency oscillation often resulting from a positivefeedback path in an amplifier system.
在音响设备中出现的振荡频率极低的低频振荡，常因放大系统的正反馈回路引起。
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The article analyzes the frequency characteristics of RC series parallel circuits and the symmetrical circuits, through studying the effectiveness of the positive-negative feedback to the amplifier.