I have an OLD speaker i found (JL audio) 10". It has no writing on it. I hooked it up to a CD player i have with some speaker wire and held it over a bucket, it sounds pretty good, maybe a little dull but that could easily be the bucket. My question is... How do i know if it is a subwoofer, or just a speaker? or is there even a difference. I offered it to a friend to use as a sub in her truck (she has an amp of her own) will this work, or should i just scrap it?