Place a standard bed pillow in the drum head. Kick the pedal to test the sound. Try moving the pillow around inside the drum head, such as closer to the back head or closer to the front head.
Add a couple bath towels to offset any overdampening effects produced by the pillow. Kick the pedal and play with the arrangement of the towels. Listen for which placement the best sound comes from. If the drum still sounds too light, try adding a rug or carpet square to the bass drum.
Fold up one or more bed sheets or other thin linen material. This can be the icing on the cake of a really great-sounding bass drum.