Q I just installed a TrueMarine audio system down in the saloon with external speakers out at the helm. While sailing and at anchor, our stereo system is the best. But back at the dock, when plugged into shore power, it is the worst! An annoying hum ruins any mode of music reception. What gives?
Jack Howard, Marina del Rey, California
A That’s easy—it’s your battery charger. But don’t blame the charger, as there is always a small AC power hum associated with most units. And don’t blame the stereo, either. The filters needed to cancel out the AC hum would be far too large to fit inside its case.
One solution is to turn off your charging system when listening to the stereo. Better yet, put your charger on a timer so it comes on only when you’re sure you won’t be listening to your audio system. Another solution would be to install an isolated 12-volt battery just to run your stereo. You could then charge this dedicated battery with a small solar panel.