Rock The Boat Audio

Marine Stereo Installation Tips

By Matt Champneys

Music can be a big part of the enjoyment of boating. But getting high-quality sound on a boat is not always easy. Follow the tips below to ensure the best quality sound on your boat, and to save yourself future repair and replacement work.

For help choosing the right equipment for your situation, select from the following:

Head Unit Mounting Considerations

When mounting your stereo consider that CD player models should not be mounted at an angle greater than 30 degrees. The recommended angle is not more than 20 degrees. While you could potentially mount the stereo completely on it's side and it would play a CD, you may lose the shock protection built into the unit. As soon as you hit that first wave the CD could slip out of position and damage the internal workings. If you want to mount a stereo on it's side, you probably want to check with the manufacturer before doing so.

While all of our stereos are equipped to handle the shock of bouncing over waves, in most cases (but not all), they must be mounted horizontally to realize this benefit.

Speaker Mounting Considerations

There are 2 different ways to mount marine speakers:
  1. Flush Mount Speakers Can be installed in tight spaces and out of the way of most activity. However, you also have to cut a hole in your boat to get them in place. Flush mount speakers must have adequate air space around the cone when they are mounted in order to get the best frequency response. Also, you don't want any other open air path behind the speaker. Both of these conditions could result in a serious loss of bass response.

  2. Box Speakers Don't require you to cut a hole in your boat and the box enclosure is already set for optimum performance of the speaker so you don't have to worry about the air space around it. The only real disadvantage is that they can take up space on your boat that flush mount speakers don't.

Aiming and Positioning Speakers

When installing speakers on deck, it is important to consider that speakers are very directional, which means they send sound in the direction they are pointed. You may be amazed at the drop off in sound when a speaker is pointed slightly away. In a home or car direction is less important because there are so many surfaces for the sound to bounce off. On an open deck sound can get swallowed up in the open air rather quickly! Be sure to point the speakers where your ears are going to be.

When selecting speaker location keep in mind that stereo sound is much better than mono sound and you will want to be able to hear from two speakers at once. Stereo sound is more realistic because our brains interpret the distance and location of sounds based on what we hear from both ears and comparing the difference between what each ear is hearing. Stereo fools our ears by producing one set of sounds for each ear from two speakers, each similar, but slightly different. You will get the best sound if you position your speakers so both of a stereo pair are pointed at your ears at the same time. If you can only hear from one speaker you will only be getting half the experience.

Wiring Speakers

You can use regular speaker wire if you like, but keep in mind that copper is very vulnerable to corrosion when exposed to moisture and air. Make sure that the plastic coating on the wire is intact from end to end. Sealing all wiring connections with liquid electrical tape is an excellent idea. If you are particularly concerned about corrosion, you can use 18-gauge doorbell wire or any other solid core wire. Braided wire gives more opportunity for air to circulate around the metal and therefore more opportunity to corrode. Tinned copper marine wire is braided, but the copper is treated so it won't corrode, making it an excellent option.

Make sure positive terminals on speakers are matched with the positive side of the stereo output; i.e., they are connected "in phase." Speakers that are "out of phase" because some connecting wires are reversed will result in some tones canceling each other out and an audible reduction in sound quality.

Speakers connections out of phase will not physically harm the stereo or the speakers. If you are not sure which speaker terminal is positive, place a AA or AAA battery across the terminals. When the positive terminal of the battery touches the positive terminal of the speaker, the speaker cone will move forward.

Power Considerations and Wiring Methods

It is important that your speakers can handle the power load that your stereo can produce, otherwise you run the risk of blowing your speakers. Be aware that using higher power rated speakers does not necessarily improve your volume. It is the amplifier that provides the power.

For most installations we recommend using only one speaker per amplified channel especially if you are using the amplifier built into your stereo head unit. For most head units, that means 4 speakers.

It is possible to use more than one speaker on an amplifier channel, but you must be careful when doing so because if not set up properly you can damage your amplifier and/or your speakers. This has to do with resistance measured in Ohms. All of the speakers we sell are 4 Ohm speakers unless otherwise indicated in the description. An amplifier will have documentation describing the power output of the unit at varying levels of resistance or Ohms. The Ohm rating of the speakers and the method of wiring determine the resistance in the channel. There are two different methods for wiring multiple speakers to one channel.
  1. Serial This is when you connect a wire from the positive lead on the amplifier to the positive lead on speaker 1. Then you connect a wire from the negative lead from speaker 1 to the positive lead on speaker 2. Finally, you connect a wire from the negative lead on speaker 2 back to the negative lead on the amplifier. The whole thing forms a loop. With this method the resistance increases with each speaker you add. Two 4 Ohm speakers wired this way create 8 Ohms of resistance. The result is basically as follows. If you have a 50 watt channel on the amplifier, the power is divided between the speakers, 25 watts to each. Keep in mind that there is a limit to the level of resistance an amp can handle. In most cases you don't want to exceed 8 Ohms on a channel so generally no more than 2 speakers on one channel.

  2. Parallel This is when you wire the positive and negative leads from each speaker directly back to the positive and negative leads of the same channel on the amplifier. Interestingly, this has the opposite effect and actually decreases resistance in the channel. Two 4 Ohm speakers wired this way will lower the resistance in the channel to 2 Ohms. The result is basically as follows. If you have a 50 watt channel, each speaker receives 50 watts, essentially doubling the power output. Again, keep in mind that not all amplifiers are built to successfully do this, so read the documentation for your amplifier. Adding too many speakers to a channel can lower the resistance to a dangerous level that could damage your speakers and/or your amplifier.

    When wiring speakers in parallel you can see the benefit of starting out with speakers of higher resistance (such as 8 Ohm speakers over 4 Ohm speakers) so that you don't lower the resistance in the channel too much by adding speakers. On the other hand, if you only want to use four 8 Ohm speakers in your system, you may be better off to wire them in parallel to only 2 channels of your amp, rather than one speaker on each of 4 channels.

Using a marine stereo in a backyard or other non-mobile application

Many of our customers use our stereos in backyard barbecues, pool and hot tub areas, and other land based outdoor applications. An important consideration is that all of our stereos are made to run off of a 12 volt marine or car battery so you will need some kind of power adapter in order to power one of our stereos from household current. We sell a high quality 10 amp adapter for this purpose or you can pick one up inexpensively at an electronics store like Radio Shack. The important thing is that the adapter provides enough amperage for the stereo. Many adapters just don't have enough amps. You will need a minimum of 5 amps to power your stereo adequately. Sometimes people will use a notebook computer adapter because they usually have higher amperage.

Power adapters are not waterproof, so they will need to be positioned in an area where they are out of the weather. If necessary, you can run longer wires between the stereo and the adapter in order to position them where you need them. Use solid core doorbell wire for this purpose which is perfect for low voltage outdoor situations.

When installing using an adapter you will need to connect both the constant power wire and the switched power wire to the positive connection on the adapter. The ground wire will connect to the negative connection on the adapter. Consult the wiring diagram that come with your stereo for help.

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