Originally Posted by myriadcorp
Whenever I run my XT32 setup I have to turn the gain on my sub nearly off. It sounds great for movies but when I turn on music the sub barely makes noise. I have to manually turn the gain up to get some bass. Can anyone help me out explaining why this is happening from the XT32 setup? Thanks
Audyssey sets the bass so that it is sometimes *perceived* as lower than the non-Audyssey response, but it is, in reality, just "flat." Here is what Audyssey did to my response:
Note how much lower the overall level is post-Audyssey. This because Audyssey's primary focus is to cut the peaks. In doing so, it decreases the overall level, but it does get the response back to flat, (which means all frequencies are output at the same overall level.) The result is that, when content is played back at the level it was recorded
, it will sound in proper balance. It's important to note that this only occurs, when the content is played back at the same level it was recorded
When it is played back below the level it was recorded
, it will sound bass shy. This is due to the normal human hearing sensitivities at low frequencies. It takes higher levels of low frequencies for humans to *perceive* sounds at the same levels as mid's and high frequencies. Fletcher-Munson described these sensitivities years ago and published charts that show human hearing perception by frequency. These have been updated through further research, and are shown below:
Audyssey has done their own research on these sensitivities and determined their own curves, and they have instituted as set of offsetting curves that compensate for these decreased sensitivities at lower volume levels. Their system is called "Dynamic EQ", and it is used to increase the SPL of lower frequencies to compensate for human hearing sensitivities. Here is a measurements of the effect of Dynamic EQ at different Master Volume Control, (MVC), settings:
You can see that, as the MVC is lowered, the bass output increases, and the more it is lowered, the more the bass increases relative to the midrange and treble. If you are listening at an MVC setting of -10 or -20, and your receiver has Dynamic EQ, you'll want to engage it to restore the bass that is perceptually missing.
Turning up the subwoofer trim is NOT the same thing. Raising the trim "shelves" the bass up below your crossover. It is not rising bass by decreasing frequency, just a fixed boost at all frequencies below the crossover.