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Old 10th March 2009, 05:11 PM   #1
midside is offline midside  United States
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Join Date: Oct 2006
Default Portable system build - Need advice

I've been wanting to build a portable water proof system for quite some time now and I am hoping that some forum members would be able to recommend some parts for this build. It will use 2 coolers, 1 for each speaker, they can then be connected for small spaces and portability with the option of spreading them out for a larger stereo arrangement. Here's what I would like:

- 30 to 50 Watts class D power per channel (pre-assembled board)
- powered by lithium batteries
- high efficiency waterproof drivers (1 or 2 way) to be mounting in the cooler for cabinets
- 1 or 2 small solar panels for extended battery life

Thanks!
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Old 12th March 2009, 04:16 AM   #2
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Join Date: Feb 2006
Location: Chicago, IL
This is going to be a pretty complex project.

You're not going to get that kind of wattage out of 12-14 v, so it's going to have to be more. I'm not an expert in this area, but I think that you will need a charge controller for the solar--and also, most of the commercially available ones are in the 12 v range, so that's a further complication.

For solar, check out the newer flexible panels. Pretty efficient, light, and you can rig up some kind of mast for them to orient them to the sun, rather than having to move the box around.

Also, look up and read through the Boominator thread that Saturnus has created. His box (I hear) puts out a wallop-load of sound, so you may not need the amount of power you think. Study up on the efficiency of speakers--it's like free power. You might do well to just build a waterproof version of his general model.

For amplifiers, check out 41hz.com. They have lots of different models, which, yes you will have to assemble, but honestly, that's going to be the easiest part of your whole project.

Keep us informed,

--Buckapound
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Old 12th March 2009, 04:12 PM   #3
midside is offline midside  United States
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Join Date: Oct 2006
Thanks for the reply. After quite some time reading, I am not convinced that I will need 30-50 Watts of class D power. I am also not 100% against building a 41hz kit like the AMP6 but it seems like there are so many new advances happening with class D amps these days that it shouldn't be hard to find a pre-built amp that fits the bill.
Solar wise, I think that I will put that on hold until I find my power requirements, that leaves me with the job of picking out the amp, speakers and battery.

Here is an interesting $90 pre-built "140 Watt" class D amplifier:
http://www.rocktheboataudio.com/html/51382.html

and here is an example of some waterproof speakers for about $100:
http://www.rocktheboataudio.com/html/31991.html
They have a sensitivity rating of 91db and a shipping weight of 6lbs (probably about 2.5 pounds a speaker actual weight)

or $291 a pair for these!!!
http://www.rocktheboataudio.com/html/38561.html

DC gold also has some speakers with a 95db sensitivity rating and weight of 3 pounds each but they are $182 a pair for these:

http://www.rocktheboataudio.com/html/36547.html

I would really like to keep the speakers under $150 a pair if possible as I am thinking of using 2 pairs (a pair for each cooler, with a switch to run them single or double) with the highest efficiency rate as possible and the lightest weight without compromising sound quality. Can I ask for anything more?
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Old 13th March 2009, 12:01 PM   #4
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Join Date: Feb 2006
Location: Chicago, IL
That sounds like solid thinking.

On the amps, you can always put in an Amp6 and if you feel the need to upgrade, that is possible. Nobody can't find some great use for an Amp6 board. I can verify that they're an easy build even if you don't have too much soldering experience. The surface mount projects (amp 32 and others) are much trickier.

You might consider lead-acid batteries, and they're really easy in this application, can power an Amp6 directly, can have a small solar panel plugged in parallel with them and are quite robust. One the size of your fist can run the Amp 6 at pretty good volume for 8 hours or so.

One very big consideration will be to figure out how to stiffen up your coolers. They're a soft material, and then you're going to be cutting holes in them. You will probably need some kind of stiffening bulkheads and or braces. Note in Saturnus' Boominator how the speakers brace each other. Consider doing this even if you have to add a block of something between them.

The other thing will be figuring out the acoustics: sealed box (if this is even possible w/a cooler) bass reflex (ported) or what. It's based on the parameters of the speakers and the volume of the box. I'm not an expert on this, but many others here are, and so it might be worth posting a query specifically about this aspect on the loudspeakers forum and have people tell you the best way to find out how to come up with something that works. There will be a good but of experimentation, I expect. Coolers are cheap.You may even consider using one as your test bed, and if you cut and patch and cut and patch, you can figure out the best sound and start with a new one and do it right.

--Buckapound
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