Marine Radio Hook Up Question

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  #1  
Old 07-16-08, 06:11 AM
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Marine Radio Hook Up Question

Hey there, I currently have a cd/mp3/am/fm radio installed in my pontoon. It is connected to two speakers, on the "front" right and left wires of the unit. The radio isn't quite loud enough in my mind since you really can't hear it when at half throttle or more. I would just like some direction on what others have tried or done to fix similar issues.

My radio puts out 45w x 4 and the speakers are 160w max, 45w RMS.

Question 1: Is the 45w x 4 listed as a max power for the head unit, or is that the RMS power....is it only really pushing out 10w or so to my speakers???

Question 2: If I were to get an amp that was a 200w amp that would push out 100w per channel, would that do a lot of damage to the speakers, taking them over the RMS, or is it fine to go over as long as you don't go over the peak value?

Question 3: Since the "rear" right and left wires are unused, can I connect both the "front" and "rear" right wires to one speaker and the left to the others and get more wattage to each speaker, or would that somehow damage the speakers and/or head unit?

Any help is appreciated, thanks.
 
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  #2  
Old 07-19-08, 07:03 AM
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Originally Posted by wingrider78 View Post
Question 1: Is the 45w x 4 listed as a max power for the head unit, or is that the RMS power....is it only really pushing out 10w or so to my speakers???
Usually it's max ("peak") power, and depending on the manufacturer, it may also be grossly exaggerated. (For example, they may claim it delivers 45 watts, but that 45 watts comes with 20% distortion.) 5 or 10 is probably closer to reality.
Question 2: If I were to get an amp that was a 200w amp that would push out 100w per channel, would that do a lot of damage to the speakers, taking them over the RMS, or is it fine to go over as long as you don't go over the peak value?
Underpowering a speaker is actually worse than overpowering. That's because the amp will "clip" (distort) the signal and overheat the speaker's voice coil. Amp and speakers should be rated at the same peak values. In concert sound systems it's not uncommon to see amps with 2x the rating of the speakers. Just make sure the amp's clip or overload indicators never come on. Also, be aware that many consumer speaker manufacturers also overrate their products. It's a numbers game.
Question 3: Since the "rear" right and left wires are unused, can I connect both the "front" and "rear" right wires to one speaker and the left to the others and get more wattage to each speaker, or would that somehow damage the speakers and/or head unit?
Not a good idea.

I'm going through a similar issue with a project boat I acquired this week. Gotta have tunes, and the radio & speakers that are in it don't measure up to my needs. Later today I'm installing two 400-watt amps for cabin & deck and an 800-watter for subs inside the deck seats. (Oh, and two more deep cycle batteries to power the darned things!)
 
  #3  
Old 07-19-08, 04:24 PM
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Originally Posted by Rick Johnston View Post
Underpowering a speaker is actually worse than overpowering. That's because the amp will "clip" (distort) the signal and overheat the speaker's voice coil. Amp and speakers should be rated at the same peak values. In concert sound systems it's not uncommon to see amps with 2x the rating of the speakers. Just make sure the amp's clip or overload indicators never come on. Also, be aware that many consumer speaker manufacturers also overrate their products. It's a numbers game.
So in your opinion, do you think that putting 100w to the speakers would be sufficient enough to get some volume out of the speakers and also be safe for the speakers???

Not a good idea.
Why not? what is the problem that would arise, would it blow the speakers, short the stereo, etc???

I see that using an amp would be the way to go, so I figure getting a 200w amp to power the two speakers at 100w apiece would be a great addition to the boat, as long as 100w wouldn't hurt the speakers....
 
  #4  
Old 07-19-08, 08:17 PM
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Originally Posted by wingrider78 View Post
So in your opinion, do you think that putting 100w to the speakers would be sufficient enough to get some volume out of the speakers and also be safe for the speakers???
Your speakers should handle it as long as you don't drive the amp into overload or clipping. However, a 100-watt amp will only increase your sound level by 3dB. Probably not enough to get above the sound from the outboard motor. In order for something to be "twice as loud" it requires an increase of 10dB, which is equal to ten times the power. If you want your speakers to be twice as loud, you'd need a 450 watt-per-channel amp. Seriously. Your speakers couldn't handle that kind of power.

Another option ...

If your pontoon is typical, the speakers are mounted very low in the seat supports. If you can get them closer to the listeners' ears you may not need the amp. I know that sounds ridiculous, but it is doable. I've seen small box-style speakers clamped to bimini top supports. The original speakers had been removed from the seats and subwoofers were installed in their place. Separate amps power the tops and subs using a crossover network.

More science content: Sound level increases by 6dB with every halving of distance. If the speakers are now sixteen feet from your ears, moving them to within 4 feet will be roughly equal to putting in a 600-watt amp.

what is the problem that would arise, would it blow the speakers, short the stereo, etc???
The stereo could be damaged. A 45w x 4 means there are 4 discrete (separate) amplifiers -- L front, R front, L rear and R rear. Each amplifier wants to power its rated speaker load, which is typically 4 or 6 ohms. The rating is based on an actual amplifier output impedance of roughly 1/10th the speaker impedance, or .4 to .6 ohms.

Electricity wants to take the easiest path. A .4 ohm impedance is much lower than the speakers' 4 ohms. When you connect the outputs of two amplifiers together, the amps want to feed each other instead of the speakers. Problem is, the amps can't handle that near-short-circuit load. The output transistors will heat up and both amps will either shut down in protection mode or burn themselves out.

Again, though, manufacturers tend to play the numbers game. Your stereo may actually contain only two discrete amplifiers with the fader connected to give you "4" channels. In this case you can connect them together. However, you won't gain anything. The total available power is still only 45 watts per speaker.
 

Last edited by Rick Johnston; 07-19-08 at 08:34 PM.
  #5  
Old 08-10-08, 08:35 PM
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Hello.. it seems to me that your best bet is to install a Second set of speakers at the other end of the Boat, as well as purchasing an amp that is a 4 way amp.. utilize both the front and rear connections on your stereo. also, your 45w RMS speakers can typically handle much more power. What really kills a speaker is the Distortion from the amp. I have run 80 CLEAN watts into a 35w rms speaker continuoulsy without any problems. if you were to get an amp that is 80-100w x 4 at a THD of less than 1% you should be fine. remember, for the most part, Distortion Kills, not clean power.

Craig.
 
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