If you have media that has been encoded using AC3 sound and you are finding that when playing it on a media player it is very low, try the following method to improve the sound volume.

Go to AC3Filter Config, and on the Main Properties page there are Presets (bottom-left corner).
Select the 'Loud' preset - you will see that both the gains are changed to maxed-out, and the 'Normalize' is ticked.

IF the Presets are not there, simply move the GAINS to their maximum setting, save and exit.

That will usually make it a lot better.