take a look at 92HD91b datasheet function block diagram and widget diagram
2.2. Mono Output The Mono Out port source selection, power state, and mute characteristics are all independently controlled by the mono output port controls. EQ does not apply to this path. An internal 2nd order band-pass filter is provided to restrict the output frequencies when using mono out to drive an external amplified sub-woofer. The following sources are available for the Mono Out pin: •DAC0 Output: When selected (by using the port connection list), the DAC0 left and right outputs are summed together. •DAC1 Output: When selected (by using the port connection list), the DAC1 left and right outputs are summed together. •Mixer Output: When selected (by using the port connection list), the mixer left and right outputs are summed together. The stereo inputs are scaled by -6dB and then summed to provide an output that is the average of the two inputs. The full scale output at mono out is designed to be about 0dBV. It is not possible to adjust to a +3dBV output level 2.3.Mono output Band-Pass Filter For many applications, the primary speakers are incapable of reproducing low frequency audio. Therefore it is desirable to implement a woofer or sub-woofer speaker. The mono output is ideal for this task. However, the frequency response should be restricted to prevent interference with the primary speakers. Typically an external filter, known as a cross-over filter, is used. The mono processing path includes a band-pass filter with programmable high and low cut-off frequencies to eliminate the need for an external filter. 2.3.1. Mixer Filter Description The band-pass filter is derived from the common biquadratic filter and provides a 12dB/octave roll-off. The filter may be programmed for a -3dB lower band edge of: 63Hz, 80Hz, 100Hz, 120Hz, 150Hz, 200Hz, 315Hz, or 400Hz. The filter may be programmed for a -3dB upper band edge of: 150Hz, 200Hz, 250Hz, 315Hz, 400Hz, 500Hz, 630Hz, or 800Hz. The band-pass filter is enabled by default with a cut-off frequencies at 120Hz and 250Hz. The filter may be bypassed using the associated verb (processing state verb -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1242891 Title: [HDA-Intel - HDA Intel PCH, playback] Playback problem & LED problem To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1242891/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
