If you feel like your marine stereo is lacking in punch, it is probably because the speakers are overworked. Standard marine speakers are good at processing high and midrange frequencies. Bass, however, is not their forte. That is why adding an extra subwoofer is always recommended. It takes the burden off of the main speakers, leaving them free to focus on the highs and mids, while the subwoofer concentrates on the low-end sound.
This division of labour improves the bass signature of your songs and enhances the overall listening experience. You get clean and crisp audio full of rich detail. No band is left out, every note is accurately captured and reproduced.
Ingress Protection (IP) Rating
The first thing you need to consider while buying a marine subwoofer is the marine-readiness of the device. Since you are going to be using the sub on a sailboat (or UTV, truck, etc.) you need to make sure it can stand up to water and dirt. For that you need to check the IP rating of the speaker.
The higher the rating, the better protected it is against the elements. For instance, a rating of IP55 means the gadget is sufficiently protected against dust and water jets from any direction, such as from hose pipes. A rating of IP67 means it is completely dustproof and protected against total immersion in water up to 1 meter for 30 minutes.
UV, salt and fog resistance
Apart from water and dust, your marine sub will be exposed to sunlight, salt water and fog on the high seas. Therefore, you need to ensure it is capable of operating in ocean weather characterized by direct sunlight, saline water splashes, dense fog and strong winds.
The size of the subwoofer is the next thing you need to look into. If your marine stereo system has small to average-sized satellite/bookshelf speakers, an 8 or 10-inch subwoofer will do. If the speakers are large and floor-standing, you might want to go for a slightly larger sub, like a 12-inch speaker.
If you need the sub for a cozy and compact sailboat cabin, an 8 to 10-inch sub will suffice. If the space is bigger, like a party hall on a ship, we suggest you go for a 15-inch sub.
Remember, big doesn’t always mean better. The sub must match the size of the speakers and the size of the room it is put in. Placing a huge sub in a small room will likely overwhelm the audio and keep you from fully enjoying the music.
Subwoofers come in various makes such as component, enclosed, powered and vehicle-specific subwoofers. Component subwoofers come speaker only. They need to be mounted in a subwoofer box and wired to an amplifier. Most component subs are compatible with both sealed and vented enclosures.
Enclosed subs come pre-loaded in a subwoofer box and you just need to hook them to an external amp. Powered subs come pre-fitted with an amp inside a subwoofer box. They are great for adding bass to small spaces like cars and boat cabins.
Vehicle-specific subs, as the name suggests, are designed for specific vehicles keeping in mind the interiors of the automobile. It allows for discrete installation in car doors and trunks for better aesthetics.
Sealed or ported enclosure
While selecting a box for your marine subwoofer, you need to make sure it gives you the right amount of bass and also fits the space you plan to install it in. Sealed enclosures (also called acoustic suspension) generate tight, accurate and responsive bass.
They are small in size. They do not have any holes and the air does not move in or out of the box. This kind of enclosure is best suited for jazz and classical music.
Ported enclosures (also called bass reflex enclosure) produce powerful bass, but are twice the size of sealed enclosures. They have vents in them for movement of air. They are excellent at delivering high-impact bass in hip-hop, rock and EDM.
Installation details need to be studied very carefully. Note the cut-out diameter and cut-out depth of the subwoofer. It must fit the space on your boat you have earmarked for the sub.
You don’t want to buy the sub and then realize that it is too big or too small for the space. If you already have an existing fixture where the sub can go in, measure the hole and accordingly look for a sub that fits that hole.
If a fresh hole has to be made in the paneling, make sure the sub and its mounting brackets fit the available space where you want to have them installed.
Peak power and RMS power
Peak power is the maximum amount of power a sub can put out at a given point. RMS power, also called continuous power, is the average power a sub can deliver over an extended period of time.
While selecting a marine subwoofer, close attention must be paid to the RMS power as it is a more realistic indication of the power handling capability of the device.
Choose a subwoofer that can process frequencies between 50 to 250 Hz.
For marine use, a subwoofer with an impedance of 4 ohms or lower is great.
The impedance of a subwoofer is a measurement of the load or electrical resistance it places on the amplifier. The sub is like a big resistor, and the impedance, measured in ohms, indicates the amount of power it can handle from the amplifier.
The lower the impedance, the more current will flow into the speaker. More current means the load on the amp will be more and it will be required to produce more power. Here is a simple way to understand the relationship between impedance and amp power.
Lower impedance → more current → greater load → increased power
Higher impedance → less current → smaller load → decreased power
Other features to consider are cone material and surround material. Since the sub will be operating in a wet environment, a polypropylene cone and rubber surround are preferable.
Polypropylene and rubber are resistant to water, and hence, will last longer. The speaker should also have a sturdy grille for safeguarding the device from accidental knocks.