Sounds like the console and horns are on different phases. Turn on one or two 240V resistive loads such as an oven or burner. If that solves the problem you are on two different phases if not it is still possible. Start by putting them on the same circuit, if that woks keep expanding if not be sure you have no plug strips, ups or other electronic devices plugged in. Sony TV’s are especially bad. If you read through the postings you will probably find somebody has had a problem with just about every device in your home. There are many articles posted here telling how to bridge the two phases.
Good Luck
Gil Shultz
