The Yamaha SR-50 is a Natural Sound Surround Processing Amplifier designed to enhance audio playback. It features various processing modes including Dolby Surround, Natural Surround, and Simulated Surround to create immersive sound effects from different source materials. The unit includes controls for volume, delay time, and input balance, as well as switches for speaker selection and high/low frequency filtering.
Low frequencies around 70 Hz can be enhanced when this switch is depressed.