Radio and Speakers for the boat

tom52

tom52

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I am intending to fit a car radio on the boat and want a pair of speakers in the cabin and a pair in the cockpit.
Lots of cheapish jvc, sony, pioneer, panansonic etc. radios about that will play MP3/WMA with an Ipod input, so I am spoiled for choice.
I am not looking for hifi, but undistorted sound at a volume I can listen to comfortably in the cockpit whilst sailing in a F3/4,
and also in the cabin in the evenings. The boat is 31 feet so the cabin is modest
The budget is about £70 radio and £30 for each pair of speakers.
What is the minimum RMS per channel I should be looking for ?
And what about speakers
Most car radio speakers seem to be 4 ohm impedence, most waterproof/cockpit speakers seem to be 8 ohm impedence.
I guess I have to match the impedence of all four speakers ? Even if I never have the cockpit speakers and the cabin speakers on at the same time ?
And each speaker should be rated for output to a similar RMS as each radio output channel ?
Does higher impedence mean more power consumed to produce the same volume as more flimsy lower impedence speakers ?
Any advice gratefully received, thanks
 
Car radios use a complimentry symetry output stage which means that load impedance of the speakers is not so critical. A lower speaker impedance than specified fopr thee radio can melt the radio at full output while a higher speaker impedance will simply mean that less maximum power is available.

In practice because perceived sound level is a logarythmic function at full output you could barely perceive the difference and of course you could not stand full volume anyway. Consider that once upon a time a high quality valve radio had an output power of 3 watts and a good portable transistor radio had a max output power of 1/3 watt you realise that yopu don't need very much power. Granted modern car radio speakers in being built rugged enough to cope with high power and wide frequency range they sacrifice efficiency so more power is required.

If you do not have the lowest impedance specified impedance then the speakers will not suck all the available power from the amplifier which means the amplifier does not draw as much current from the battery.

So it is all a bit like buyinbg a car that will do 200MPH when you have a 30 MPH speed limit. It is little more than bragging stuff.
I am assuming here that you don't want to annoy the entire marina with your loud music and destroy your hearing in the process. You will probably only ever run the radio at a max output of 100 milliwatts ie 1/10 watt. So don;'t worry about power output.

If you have big batteries and use the boat regularly you can hook up the memory power supply to the always on circuit of your boat so radio stations are stored. I found however that the drain on my meagre supply was too much on the radio I had fitted. I ended up fitting an old mechanically tuned radio which is always on station but no CD.

A modern (good) radio will have provision for front and rear speakers and a fader to control both. However you might lkike to fit a kill switch or reduce volume switch in the cockpit to save a trip to the cabin to turn the music down if you want to communicate.

I tend to do without music when sailing even though it is available.
olewill
 
Thanks Will, I think I got most of that.
A kill switch in the cockpit to disconnect the speakers sound like a good idea. Is it OK to have the radio still on with the speakers disconnected, or will that damage the radio ?
 
[ QUOTE ]
A modern (good) radio will have provision for front and rear speakers and a fader to control both. However you might lkike to fit a kill switch or reduce volume switch in the cockpit to save a trip to the cabin to turn the music down if you want to communicate.


[/ QUOTE ]


You should not need a kill switch, most modern radio's will have a telephone attenuation control or touch the power button once and it attenuates, this also works on the remote of the last two radios I have had.

For speakers I bought mine from CPC for the cockpit, but they are more popular nowadays so available more widely.

marine speakers

I also built a circuit for the remote as unlike a car it is difficult to place it in line-of-sight from the cockpit, but many modern stereos come with a remote infra-red eye, this is worth looking out for.
 
Has anyone found that car speakers don't seem to last long on a boat? We seem to get only a couple of seasons before they start to sound a bit fuzzy. The poly cone marine ones do last longer but not indefinitely like a domestic stereo. Don't know whether its the corrosive marine environment or more load on boat speakers since they are usually mounted in bulkheads giving a much bigger coupling space than a car door.
 
No it will not damage the radio to open the wires to the cockpit speakers. Or alternatively you could fit a resistor in each speaker line about 40 ohms should do (one watt) which is normally bypassed but is put in circuit when you want to reduce the sound level.
The remote control sounds great providing the remote will handle the cockpit conditions. olewill
 
Please can you explain what you mean by "I also built a circuit for the remote" as I have this problem with wanting to control an out of sight radio. Do you mean that there is a bit of kit that I can use which remotely transmits a signal to a point which is in line of sight?
 
Tom,
Am in the process of doing exactly this project for my boat. I have just bought a Panasonic FM/CD player on eBay and a pair of Goodmans car back shelf speakers. Total cost less than £55 for all new kit. This to replace the clapped out set up on the boat.

I plan to install two speakers only so will have two unused channels but the radio has 50 W per channel so should be fine. I recently asked a question on this forum about how to leave these channels unused and understand that you simply don't connect anything to the unused speaker outlets.

I anticipate having to retune the unit each time I go on board since I want to avoid excessive drain on the leisure battery so will not leave the radio permanently connected (as it would be conventionally in a car).

PM me if you want me to share the eBay seller data with you.
Morgan
 
It's been my experience that a cheap radio can be made to sound good by decent speakers, and a good radio will always sound bad throgh cheap ones. I have an old radio CD of mediocre quality and indeterminate age and a good set of Pioneer speakers that aren't far from their 20th birthday but still sound good, having outlasted 4 radios and as many cars. I'd be inclined to look at some of the cheaper radios and pay a bit more for the speakers.

FWIW, I've also found that quality of sound is more or less proportional to their weight. Heavy = big magnet.

Which reminds me. Car speakers aren't usually shielded, so either side of the compass may not be the best place to fit 'em...
 
Steve,
Thanks for the warning about the speakers and the compass. It should not be a problem with the mounting locations I have in mind. I also agree with your comment about speaker quality but am a bit strapped for space and the Goodmans ones I bought are not bad - cheap too!
Morgan
 
Basically, it is a remote sender.

You fix a infra red sensor in a prominent position and hard wire is to an infra red transmitter opposite or at least within sight of the stereo.

I have found a company who actually sell them, kits or pre-built..

IR remote repeater kits

remotesensor.jpg


Here you see my receiver eye, this is connected via a cct to a transmitting IR LED just above my stereo. It works very well, you can buy a kit which does the same from the company above. The eye I used came from one of the multitude of rubbish Chinese head units I sent back. inside the dome it is just a IR receiving LED, you need to house them in black to stop them being affected by sunlight. maplin sell IR enclosures and similar.

There is no easy solution, the site above seems to be about the best for your needs, hope this helps.

J
 
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