jax and nm are correct. reverse the channels of the speaker cable and if the noise moves to the other speaker, the fault is the amp or before it. if it stays in the same speaker, disconnect the jumpers and hook the speaker wire to the woofer and then to the tweeter to locate the faulty driver. what amp are you using? a tube amp?
only one source? have you tried reversing the channels of the source to see if the problem stays or moves to the other channel?
b