fixed-tuned amplifier

例句：

1. 1. The fixed-tuned amplifier is used to amplify the audio signal.
   固定调放大器用于放大音频信号。
2. 2. The fixed-tuned amplifier was designed to improve sound quality.
   固定调放大器被设计来提高音质。
3. 3. The fixed-tuned amplifier is essential for recording studios.
   固定调放大器对于录音室来说是必不可少的。