First demonstrated in 1975, Peter Walker's 'Current Dumping' or 'feed forward' output stage topology would go on to define Quad's famous 405 power amp and stir a debate about its efficacy that continues in some quarters to this day. In many respects, and by combining high efficiency with low distortion, the original current dumping amp was decades ahead of today's 'green' offerings. This win-win is achieved by combining a relatively blunt but high power Class B amp with a very low power but equally low distortion Class A line amp that defines the overall linearity of the circuit. Distortion is reduced in conventional fashion by a feedback loop around both the line amp and Class B current dumpers, the compensated output of the former driving the latter.
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机译：Peter Walker的“ Current Dumping”或“前馈”输出级拓扑结构于1975年首次被证明，将继续定义Quad著名的405功率放大器，并引起对其效力的争论，这种争论一直持续到今天。在许多方面，通过将高效率与低失真相结合，原始的电流倾销放大器比当今的“绿色”产品要早几十年。这种双赢是通过将相对钝但高功率的B类放大器与极低的功率但同样低失真的A类线路放大器相结合来实现的，该放大器定义了电路的整体线性度。通过围绕线路放大器和B类电流吸收器的反馈环路，以传统方式减少了失真，前者的补偿输出驱动后者。
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