Car Stereos: kicker 03kX3 crossover, rcas, negative battery

Question
I have my headunit output, connected to the preamp, then to the crossover, amplifier,speakers.i keep hearing alternator noise, If i unplug the RCAs from the output of the crossover, there is no noise,if i unplug the RCAs from the input to the crossover,there is no noise, if i remove the RCAs from the output of the preamp there is noise. The RCA between the preamp and the crossover was unplugged,no noise. I then used a new RCA one end connected to the input of the crossover and the other end free, there is alternator noise. Is there a problem with the crossover and how could i repair it?

Help please,thank you.

Answer
Dale, Be sure the ground wire to the crossover is as short as possible.  It sounds like a ground issue.  The wire should be connected to a bare piece of metal.  If the ground is not good enough, the negative power will find another outlet, which is not as efficient as the negative battery to frame connection.  If it is not that good, it always will make noise.  Hope this helps, Scott