This works particularly well with smaller bass drums.
1. Tune both heads to their lowest viable pitch.
2. Add an extra turn or half turn to each tuner...
3. ...then de-tune *alternate* tension rods by half a turn or so - so for an eight-lug drum, for example, you would de-tune 2, 4, 6 and 8.
This has the effect of disrupting the drum's fundamental pitch, so you don't hear much of the 'boom' - just a good, meaty thud. Add damping of your choice to finalise.
Oddly enough, it's harder to do this accurately by simply de-tuning alternate rods upwards from step 1, which is why I don't suggest it.