depends on the speaker box and material it is made out of, most likely medium sized, most likely made out of wood? Personally I would probably try to use a speaker that has a large enough Bass response displacement hole in either the front or the back so you have something to work with. You could use a computer fan but those I believe require a little bit of jimmying since they don't have a standard power cord. Given the probability that your speaker is not that big, maybe you would want to wait until someone posts who has experience with rigging up computer fans however.