for "bass drums" yukichigai is pretty much right. you can tune them to anything you want. but just as a very rough estimate from having recorded bass drums and seeing where the meat of the tone is, they can be anywhere from 40-120 Hz. Figure on the lower range for rock music or hip-hop samples, higher for jazz or other lighter styles.
timpini play specific pitches, controlled by a foot pedal and changed while playing to play semi-melodies. the lowest they are commonly written for is C2, which is about 65 Hz. 4-string bass guitars go down to 41 Hz. a 5 string bass guitar can go down to 30 Hz or 27.5 Hz if it's tuned down a bit. pianos go down to 27.5 Hz as well. big pipe organs can go below 20 Hz.
if you're asking as a stereo-related question, just make sure you can extend to 25-30 Hz and you'll probably be fine.
BTW: i found those pitches by searching for "musical instrument frequency ranges" on yahoo.