Let's say I've got a pair of speakers, crossover set at 2000 Hz. With the help of a test tone generator, I am able to determine that there is no output from the left tweeter from 2000 Hz to about 3600 Hz (response is good at 4000 Hz and up). On the right speaker, output in this range is fine. I know very little about the engineering behind crossovers, so I'm wondering do I have a busted crossover or tweeter in the left speaker?