AVS Forum Addicted Member
Join Date: Feb 2010
Location: Monument CO
Mentioned: 66 Post(s)
Tagged: 0 Thread(s)
Quoted: 3152 Post(s)
Maybe a picture will help in addition to the previous (very good) explanations. The volume control is a variable resistor that allows whatever signal level you desire from the AVR to be passed on to the subwoofer circuit. Note this is a very simplified look and different designs implement the control differently. In this circuit, the variable resistor (potentiometer) attenuates the signal except at full rotation, but the overall circuit has gain blocks (triangles representing amplifiers) before and after the control so the overall signal level depends on them as well as the level of the volume control. In other words, there is likely still a net gain when the volume control is at lower levels.
Note the AVR also has a volume control and usually a gain stage after it (second picture) so finding the actual gain from input to output can be a bit tricky to determine without comprehensive schematics or measurements.
In practice it is usually better for noise floor to have more gain early in the chain, and for distortion it is usually better to have the gain later in the chain, so it is up to us to find the right balance. With AVRs, adjust the sub's volume so the AVR's trims are at 0 dB or perhaps -3 to -6 dB if you like to boost the sub after running your room calibration, and that will generally provide a good trade between noise and distortion.
HTH - Don
"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley