A good rule of thumb that I follow is if the noises sync up with your pedal rotations, it's most likely the BB, the crank, the ring or the chain...if the noises sync up with your wheel rotations then it's most likely the hub, the freewheel, the chain or a loose spoke (or spokes) in your rear wheel...
My experience with ACS freewheels is, they make a lot of pinging noises...Especially if you're using a flip flop hub with only a few threads to stick a freewheel on...