Marine speakers are essential for stereo sound in a wet environment, whether on a boat, an open off-road vehicle or even near a hot tub or pool. They thrive in places a standard car stereo speaker would be destroyed. Sealed drivers and waterproof cones can withstand a hosing down of a deck, rain and sometimes complete submersion. Corrosion resistant parts withstand the salt air and moisture.
With that established, what are the best speakers for your situation?
FIRST: Consider Cutout Size
If you are replacing existing marine speakers you may have a cutout hole that you need to fit the replacement speakers into. This will narrow down your search considerably so that must be the first consideration.
If you will be cutting a new hole for new flush mount speakers, you need to first measure the area so that you know the limits to the speaker size you can fit. As a general rule, larger speakers will give you better overall sound, so try to find the largest space available. Don't just consider the cutout size, but the depth of space behind the speaker. There needs to be enclosed air space behind and around the speaker to improve the resonance of the sound. Make sure the speakers are pointed in the direction of your ears.
You may want to consider box speakers if you can't find a place to cut a hole. Box speakers already come with an enclosure so you don't need to worry about having the proper amount of air space around them.
The number of speakers you purchase will depend on how you plan to power your system. Take a look at our installation page for more information.
SECOND: Consider Speaker Quality
The quality of a speaker depends greatly upon the frequency range of sound that it is able to reproduce. The easiest frequencies to reproduce are the mid-range frequencies while deep bass and clear highs are more difficult. This is the difference between say, a telephone speaker and a stereo speaker. Telephone speakers reproduce only mid range frequencies and that is fine for a human voice, but high quality realistic sound needs much more bass and treble.
There are essentially 4 different types of speakers:
Dual Cone Speakers Have only one driver or sound output source, but use two different cones, one larger and one smaller. The larger is for mid-range and low frequencies while the smaller cone is for high frequencies. This works fairly well, but does not deliver as broad a spectrum of sound frequencies as the other types of speakers that use different methods. These marine speakers also tend to be less expensive which is a consideration.
Coaxial Speakers These marine speakers use multiple drivers to handle the different frequencies that make up sound. The term coaxial refers to the fact that they are really one speaker wrapped around another speaker. The frequencies are divided electronically by a device called a crossover so that each driver is only required to reproduce it's own block of frequencies. The tweeter which handles high frequencies is usually in the center and is surrounded by a woofer which handles mid-range and low frequencies. Generally, you will get better performance from a coaxial speaker than a dual cone speaker, but not necessarily as good as a component speaker.
Are similar to coaxial speakers in that they have multiple drivers, but the tweeter and the woofer are completely separate. This configuration helps reduce cross phase distortion where vibrations from the woofer might cancel out frequencies in the tweeter. Most often, you will find a component speaker setup in marine box speakers, but there are also flush mount component speakers available with a separate woofer and tweeter. This setup has great advantages, but keep in mind that a lower quality component speaker will not necessarily sound better that a higher quality coaxial speaker.
Subwoofers are designed only to handle bass frequencies. Unless you are looking for thunderously heavy bass, you probably won't need a subwoofer. Quality coaxial or component speakers alone can give you nice deep bass response without threatening to shatter your windshield. It just depends upon your opinion.
If you do decide you want to use a subwoofer, make sure that your system has a "crossover" in it somewhere between the head unit and the subwoofer speaker. A crossover splits the freqencies up so that only the low frequencies are sent to the subwoofer. Trying to run all frequecies through a subwoofer can make everything sound like mud and you won't get the "punch" in the sound you are looking for. Crossovers come in various forms. Some head units have subwoofer output which has already been "crossed over" which you can run right to an amp to power the subwoofer. Also, many amps have a built in crossover so you can run a full range line output from your head unit to the amp and then the amp will only send the low frequencies to the subwoofer. Last of all, most single unit powered subwoofers have a crosssover built right into them.
A subwoofer requires lots of power and in most cases you need a separate amplifier for it. If you don't provide your sub enough power you won't notice any difference in the sound. Some subwoofers are powered with their own built in amp and that takes care of it. Alternately you can buy the amp and subwoofer speaker separately. Keep in mind that powering a subwoofer with a standard powered speaker channel will probably not give you the performance you are looking for.
Depending upon your situation, it is likely you may only need one subwoofer. The reason for this is that at the low frequencies it is almost impossible to discern any stereo separation in the sound. You feel the bass more than hear it. In a music mix the bass is never panned to one side or the other of the stereo spectrum, but is always solidly in the middle. Also, subwoofers are not very directional, meaning the low frequencies spread out all over rather than only moving the direction the sub is pointed.
THIRD: Consider Power Handling
To avoid damaging the speakers it is best to use speakers with a higher power handling ability than the stereo amplifier. On the other hand, it is important to understand that power handling capacity does not necessarily equal volume since the power comes from the amp and not the speakers. It is possible to get the same performance from a set of speakers with a power figure just above that of the amplifier than from speakers with a much higher power figure run from the same amplifier.
That having been said, if you think you might want to upgrade your system with a more powerful amp later, go for speakers with higher power handling so that they can handle the increase in power.
There are two important power measurements to consider:
Peak Wattage: This is the maximum power the speaker can handle at any given instant.
RMS Wattage: This is the average power the speaker can be reasonably expected to handle over time.
Unfortunately manufacturers like to stress the peak wattage of their speakers (because it sounds cool) while the RMS (which is actually more important) often goes into the fine print or is not published at all. Ideally, you want to get speakers with an RMS power figure above that of the RMS figure of the stereo head or amplifier. In the absence of RMS data, go ahead and compare the Peak Wattage.