Southern Boating

Can’t Upgrade?

Many "legacy" stereo components have a large variety of faceplates.

Then update your existing audio.

Your boat’s stereo is older, it still sounds great, but there is no Bluetooth interface for your smart phone to stream to. The stereo’s auxiliary input is already used, or there isn’t one at all. You could replace your stereo, but this is often not as simple—or affordable—as it sounds. Many older boat stereos such as the Clarions were larger and replacing them takes more effort than many would realize. Since the footprint was larger than newer stereos, it now requires fabrication of a cover plate and handling associated cosmetic problems. The remote control in the dash may also need replacement and it may be difficult to pull wire. So how do you adapt your existing stereo to use new technologies?

There are many types of adapters and approaches that can breathe new technological life into your stereo. We’ll start with the stereo’s auxiliary input—on many boats it is already being used by another device such as the TV or a DVD player. In our first case we can have multiple devices share the stereo’s auxiliary input, but only one device can use it at a time. The easiest way to do this is by using audio cable splitters, which are inexpensive, available in almost any plug configuration and an easy way to share the input. The new input could be as basic as a 1/8″ headphone mini-jack that plugs into your smartphone or iPod, or use an audio switch box to select the source so that multiple audio inputs can share the port.

Other options for new audio sources include adding Bluetooth to your existing stereo that consists of FM modulators and FM transmitters. The differences between these two are that the FM transmitter sends a low power FM signal that will be heard by your stereo’s antenna, while the FM modulator is connected directly to the antenna.


To use the typical FM transmitter, select an unused FM frequency, set the device to transmit at that frequency, plug in your audio source, and presto. There is zero wiring to deal with, but a downside is that in most cases, you will need a 12VDC receptacle nearby to plug into—the closer the better. The range is limited, and about 20 feet is the maximum.

The FM modulator does a similar job but in a much different way. Unplug the stereo’s antenna wire and plug it into the modulator. Then plug the modulator’s antenna cable into the stereo. The modulator injects a strong FM signal directly into the antenna wire. The signal source is typically cleaner and much less prone to interference. The downsides are that it requires removing the stereo to install, it has to be wired to 12-volt power, and in most cases, the frequency options are fewer (2 to 8 max).

Given the choices between these two approaches, I favor the FM modulator over the FM transmitter. It requires physical installation, meaning the stereo will have to be extracted at least partially to install it, but the gear ends up being tucked away out of sight. Overall, the sound quality is better in most scenarios. Two good options to consider are the Scosche Universal FM modulator and Audiovox FM100A.

The world of Bluetooth comes in several similar adapter forms. There are FM transmitter versions, which have the same characteristics discussed earlier, and ones that require connection to your stereo’s auxiliary input either directly or through a FM modulator. A good Bluetooth option for boat owners is Wet Sounds Bluetooth volume control WW-BT-VC. This is a small, water-resistant controller suitable for both console and interior mounting. It requires 12VDC connection to ships power and has a 1/8″ mini-jack stereo output for connection to your stereo. It pauses (mutes), changes tracks and controls the sound volume all with one small knob. As with other audio sources you can use either a FM transmitter or modulator for input to your stereo if need be. It pairs quickly and has good wireless range.

As a final note, your stereo’s auxiliary input is designed to accept what’s called a “Line Level” audio signal, and in some cases, this can cause minor problems. The headphone jack on your smart phone or iPod is like a line level output on a small dose of steroids. You won’t hurt your stereo with it, but if the input volume is turned all of the way up you can overdrive the auxiliary input causing sound distortion. So the general rule of thumb is to have the headphone jack volume turned way down and to use the stereo to control the sound volume. In the case of the Wet Sounds Bluetooth volume control, if you’re using a FM modulator you may have to play a bit with the volume settings to find a good-sounding combination.

There are many options available to get more life out of your stereo, but shop carefully and take time to read the customer reviews about the products before you buy. Like many things in life, sometimes the least expensive approach to good tunes cost you the most in aggravation.

Southern Boating, April 2015 By Bill Bishop