Yamaha CS-700 Operation Manual page 29

The Equalizer setting allows selecting one of a list of pre-defined speaker
equalizations. The available choices are Voice Enhance, Bass Boost, and
Treble Boost.
The High Pass filter affects the microphones and can be used to filter out low
frequency noises in the room. The high pass filter can be disabled (None), or
set to the provided frequencies of 110Hz, 140Hz, 175Hz, or 225Hz.
The TV Audio-In Settings allow gain-control of the AUX-in input sound source.
The default setting is automatic gain control. Enabling manual gain allows the
Operator to select a pre-defined gain level from -12dB to +40dB.
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