Adjustable bass boost and damping.
20 Hz subsonic filter. The combination of the equalizer and speaker is shown in curve C, with a smooth response and a -3dB point at 15 Hz. Note that it is generally not possible to perform this sort of correction with a conventional graphic equalizer, due to the spacing of the frequency bands of the sliders. Four rotary controls are provided for each channel, to match the cutoff frequency and damping of any acoustic-suspension speaker and to set the bass boost and net damping.