for loops to cooperate with an already programmed beat it helps to know the beat per minute of: 1) your drum loop 2) the sampled loop. if you are throwing a sampled loop at 105 bpms over a 92 bpm drum loop it not really gonna line up. it's a key piece of info, especially when meshing different percussive tracks. Unless....you chop that sample up and replay it over your drums. by doing this you are rearranging the sample to "make it more yours", plus it's waay more fun.
chop and find a way to find the bpm. you can do it with your ear or gear. i have a pioneer efx 500 which has a bpm tap function, very handy. there are also software calculators, etc. find whatever is best for you and your setup/ workflow. it's definatly a frequently used tool in my studio.
