Optical circuits for optical amplifier input and output stages are described.

描述了光学放大器的输入和输出级的光路。

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Output noise may be reduced in both circuits by bypassing the amplifier input.

如果想减小输出噪声，可以在上述电路的输入端采取旁路措施。

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That means that not only the signal input into the amplifier is symmetrical but also the signal output and therefore the connection to the headphones.

ENGADGET: Sennheiser unveils HDVA 600 analog headphone amp, asks for $1,600

In order to fully exploit the sound potential of the HDVD 800 with any audio source, a rotary gain switch at the rear of the unit provides simple adaptation of the amplifier output to the audio input voltage.

ENGADGET: Sennheiser unveils HDVA 600 analog headphone amp, asks for $1,600