Originally Posted by
EarmarkMarine
There are 3 issues to the noise problem that people often have when adding an EQ to a towboat.
First, you are adding another device in the signal path and another gain stage before the amplifier. If the input sensitivity is properly matched between radio and EQ, and EQ and amplifier, then you will greatly reduce your potential for noise.
Second is the issue that David mentioned, you MUST make sure that ALL power and ground connections in the audio system (radio, EQ, line driver, amplifiers, etc) are isolated to the stereo battery bank, and all boat electronics (especially LED controllers) are isolated to the house battery bank.
Third, most of the time when people are adding a device like the Wet Sounds EQ, they are doing it specifically to get independent level control of the tower zone versus interior zone. And that often means they are running HLCD speakers on the tower. The horn on a HLCD speaker is dramatically more efficient than any other speaker in the boat and it is designed to reproduce high frequencies. When you have an audio system with a signal path that includes multiple gain stages before the amplifier, then amplified through a high powered amplifier, then sent out to a speaker that is maybe 10db more efficient than the rest of the system, you're going to hear it if you have a problem. The noise floor is often higher than it should be due to poorly matched gains on the radio/eq/amplifier, but with amplified HLCD drivers it's not uncommon to hear some ambient background "hiss" when there is no music playing. Sometimes this can be tuned out, sometimes it cannot be completely eliminated, there are many variables at work.