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Boat Forum / Electronics / February 2005Speaker installation
So I finally found a set of speakers that seemed like a good enough deal and they came in last week. I'm wondering if anyone has any input/experience installing speakers. They aren't flush mount which needs I'll need to be cutting a few holes... some of my curiosity lies in wondering if there's any certain saw blades one should use for cutting fiberglass.... I was going to just drill a few holes to start a hand jig saw... maybe tape up the area with duck tape to avoid scratching.. other than that I didn't really know if there was anything one should take precaution with. Also, though they weigh a couple pounds each, should I worry much about providing some of support to the backing... like a brace to dissipate weight on the fiberglass walls? TIA -j > So I finally found a set of speakers that seemed like a good enough deal > and they came in last week. I'm wondering if anyone has any [quoted text clipped - 13 lines] > > -j Always cover the face of the cut/drill area with duct tape...it reduces the likelihood of the gelcoat chipping. You say these are not flushmount speakers so I assume they are already installed in boxes and the brackets for the boxes are what you will be attaching to the boat. I would consider some sort of backing strap or plate the help support the brackets. Large washers are another consideration. >> So I finally found a set of speakers that seemed like a good enough deal >> and they came in last week. I'm wondering if anyone has any [quoted text clipped - 16 lines] > Always cover the face of the cut/drill area with duct tape...it reduces > the likelihood of the gelcoat chipping. NEVER use duct tape for masking. When you remove it either the adhesive will stay and is a bear to remove, or it will tear off any finish it was applied over. Use something like 3M blue tape. > You say these are not flushmount speakers so I assume they are already > installed in boxes and the brackets for the boxes are what you will be > attaching to the boat. > > I would consider some sort of backing strap or plate the help support the > brackets. Large washers are another consideration. >>> So I finally found a set of speakers that seemed like a good enough deal >>> and they came in last week. I'm wondering if anyone has any [quoted text clipped - 18 lines] > > NEVER use duct tape for masking. You are correct. I should have said masking tape. >So I finally found a set of speakers that seemed like a good enough deal and >they came in last week. I'm wondering if anyone has any input/experience [quoted text clipped - 12 lines] > >-j Where on the boat are you installing them? Most speakers I've seen are inappropriate for use in the cockpit, if that is what you are planning. Unless they have a sturdy and solid enclosure, they are strictly for inside the cabin, or maybe up high in a flying bridge. Speakers without enclosures in the cockpit, instantly become large holes for water to enter if the boat gets pooped. BB Well, these ( http://tinyurl.com/692pp ) are the ones I got. They'll be going on either side of the walkway to the open bow (at cruise the two rears can't be heard at all, really.) I can climb under the dash on either side with enough room to work, and water (though moisture might) doesn't usually find it's way into that area.. -j >>So I finally found a set of speakers that seemed like a good enough deal >>and [quoted text clipped - 28 lines] > > BB > Well, these ( http://tinyurl.com/692pp ) are the ones I got. > [quoted text clipped - 37 lines] >> >> BB The link tells us nothing about the speakers other than that they *are* flush mount. No backing plate needed. If they are exposed to the sun and sea spray I hope they are capable of withstanding the long term effects...rubber surrounds and neoprene cones. If not be prepared to be replacing them every year or two. Sometimes cheap is not always the best deal. Sorry, that was a bit uninformative.. They weigh about 2 or 3 pounds/piece. They didn't come with back braces, and they would probably mount ok... my concern is the shock of slamming over wakes over time, cracking the perimeter... "Features: * Rubber surround * Magnetically Shielded * Weather-resistant woofer * UV impregnated ABS heat-resistant weatherproof grilles * One-piece formed ABS basket* Recommended amplifier power 10-60 watts RMS, 150 watts Peak * Requires 3.45" of mounting depth and 5.63" cutout diameter * * Dual Cone: Mylar * Cone: Polypropylene * Basket: Durable and light weight ABS plastic" >> Well, these ( http://tinyurl.com/692pp ) are the ones I got. >> [quoted text clipped - 51 lines] > > Sometimes cheap is not always the best deal. As long as you are happy with them they sound fine for a marine environerment. Just mount them per the manufacturers instructions. No backing plate should be needed. If you want additional insurance use extra large washers. > Sorry, that was a bit uninformative.. > They weigh about 2 or 3 pounds/piece. They didn't come with back braces, [quoted text clipped - 65 lines] >> >> Sometimes cheap is not always the best deal. > Sorry, that was a bit uninformative.. > They weigh about 2 or 3 pounds/piece. They didn't come with back braces, > and they would probably mount ok... my concern is the shock of slamming > over wakes over time, cracking the perimeter... Get yourself a piece of 3/4" birch ply. Cut a square for each speaker, about 2" bigger than the speaker. Cut your holes in the fiberglass. Make them perfect. Put the birch ply behind the holes you've made, trace the holes onto the plywood, and cut holes in that, too. Actually, do that ***BEFORE*** you've cut it into squares. The big piece of ply will be easier to clamp to a work surface than the smaller squares. Mount the speakers with the wooden squares as bracing from behind. One thing you didn't mention: What will be the enclosure BEHIND the speakers? For any speaker, there's a very small range of correct enclosure size. Get far from that range and the speaker becomes all but useless in terms of bass response. Trying to get decent bass by dicking around with tone controls will just overdrive your radio or amplifier, and blow up your speakers in short order. Hint: In even the quietest cars, you need about 75 ***CLEAN*** watts per channel to overcome road noise. If you intend to run this stereo in a boat while the engine's running, you need about twice that much power. Otherwise, you'd better be a big fan of distortion and blown speakers. The birch idea sounds good.. Can't say I gave enclosures much though.. sounds like I need to though. .. . -j >> Sorry, that was a bit uninformative.. >> They weigh about 2 or 3 pounds/piece. They didn't come with back braces, [quoted text clipped - 19 lines] > about twice that much power. Otherwise, you'd better be a big fan of > distortion and blown speakers. Basic physics: take note of the distance sound leaving the rear surface of the speaker has to travel through the air to reach the front of the speaker. Any sound with a wavelength longer that this distance will cancel itself out as the sound from the front is perfectly out of phase with the sound from the rear. No bass in other words. An enclosure effectively creates an infinite distance from front to rear as the two out of phase sound waves can't get to each other. they are blocked form meeting by the walls of the enclosure. If the enclosure is too small the speaker ends up using up most of its power trying to compress the air inside the enclosure resulting in little low bass as well. So the enclosure has to be both well sealed and big enough to be effective. It is possible to vent an enclosure with a tuned port (often called bass reflex) allowing a smaller enclosure but that isn't simple physics any more...  SignatureKen Heaton Cape Breton Island, Canada kenheaton AT ess wye dee DOT eastlink DOT ca > The birch idea sounds good.. > Can't say I gave enclosures much though.. sounds like I need to though. .. . [quoted text clipped - 24 lines] > > about twice that much power. Otherwise, you'd better be a big fan of > > distortion and blown speakers. > Basic physics: take note of the distance sound leaving the rear surface of > the speaker has to travel through the air to reach the front of the speaker. [quoted text clipped - 9 lines] > tuned port (often called bass reflex) allowing a smaller enclosure but that > isn't simple physics any more... Good explanation. It also helps to know the wavelengths. Sound travels about 1127 ft/second in air and wavelength = velocity/frequency so... freq. wavelength (Hz) (ft) 20 56 40 28 80 14 >> Basic physics: take note of the distance sound leaving the rear surface >> of [quoted text clipped - 25 lines] > 40 28 > 80 14 All good points. If he can't build a perfect enclosure, a good ballpark figure (at least with my experience) is that most car doors are a "pretty good size" for decent 5" to 6" speakers, assuming they've got at least 10-15 watts of CLEAN power driving them. >> Basic physics: take note of the distance sound leaving the rear surface >> of [quoted text clipped - 25 lines] > 40 28 > 80 14 Holy cow. This ain't rocket science folks. >>> Basic physics: take note of the distance sound leaving the rear surface >>> of [quoted text clipped - 30 lines] > > Holy cow. This ain't rocket science folks. Actually, it's *is* science, although it's not always possible to apply it accurately in cars & boats. You just do the best you can, using the rocket science as a guideline. And even if you're building freestanding speaker cabinets for home or stage use, the science assumes a perfect speaker cone which doesn't add color of its own, which is pretty much fiction. Even so, the science works. > So I finally found a set of speakers that seemed like a good enough deal and > they came in last week. I'm wondering if anyone has any input/experience [quoted text clipped - 4 lines] > with duck tape to avoid scratching.. other than that I didn't really know if > there was anything one should take precaution with. I've used a RotoZip for this - much easier than a Sabre Saw. If its simple glass it goes through it very quickly. Mine were in the cockpit seats which had a 1/2 ply backing, so I went though 3 or 4 bits for both holes. Tape the area with masking tape, draw your circle, and have a helper with a vacuum to keep the dust down. > Also, though they weigh a couple pounds each, should I worry much about > providing some of support to the backing... like a brace to dissipate weight > on the fiberglass walls? You shouldn't need support, but you could glass in some marine ply before or after you make your hole. Before you cut into the boat, are the speakers magnetically shielded so as not to interfere with your compass? >> So I finally found a set of speakers that seemed like a good enough >> deal and they came in last week. I'm wondering if anyone has any [quoted text clipped - 18 lines] > You shouldn't need support, but you could glass in some marine ply > before or after you make your hole. They are, actually... though we're usually only on a landlocked river.... -j > Before you cut into the boat, are the speakers magnetically shielded so as > not to interfere with your compass? [quoted text clipped - 21 lines] >> You shouldn't need support, but you could glass in some marine ply >> before or after you make your hole. Those speakers are not magnetically shielded. That is not a problem as long as you keep them away from the compass...e.g. 5 feet or so. > They are, actually... though we're usually only on a landlocked river.... > > -j > >> Before you cut into the boat, are the speakers magnetically shielded so >> as not to interfere with your compass? Some folks recommend a minimum of 3 meters or ten feet separation. Wouldn't hurt to conduct a test. Probably best done with the boat out of the water so it can't move during the test. May not be a problem at all on a landlocked river, but other readers might be more concerned about the effects of strong onboard magnets on offshore navigation. Some modern speakers have amazingly powerful magnets. > Those speakers are not magnetically shielded. That is not a problem as long > as you keep them away from the compass...e.g. 5 feet or so. [quoted text clipped - 5 lines] >>>Before you cut into the boat, are the speakers magnetically shielded so >>>as not to interfere with your compass? Don't put the holes through the hull below waterline. Just a thought jofra > Don't put the holes through the hull below waterline. > > Just a thought > > jofra I hope he doesn't put hole through the hull anywhere on the boat for this speaker installation. ;-) Might be a good idea to determine what's behind the bulkhead before drilling and cutting. If you cut the hole accurately, you can use SS wood screws in correctly sized holes to attach them. JR > So I finally found a set of speakers that seemed like a good enough deal and > they came in last week. I'm wondering if anyone has any input/experience [quoted text clipped - 12 lines] > > -j Signature-------------------------------------------------------------- Home Page: http://www.seanet.com/~jasonrnorth |
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