How do you seal all seams in a box? - AVS Forum
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post #1 of 37 Old 12-04-2007, 07:07 AM - Thread Starter
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Hey all,

I'm finally getting around to building my Adire Kit 281's in a TL design. My question though is more generic. How do you seal a speaker box? On sub boxes it's usually pretty straight forward because you can reach in the huge hole for the driver and apply caulk to all the joints.

However, once I put the front baffle on my 281's, there is no way I'll be able to seal all the joints with caulk. Do you all just put a bunch of glue and hope that it is a perfect seal?

Thanks in advance,

Russell
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post #2 of 37 Old 12-04-2007, 07:49 AM
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Well you have two things going for you here,
1. you aren't moving nearly as much air as a subwoofer and
2. the box isn't sealed

this means there won't be a tremendous amount of pressure on the joints, I wouldn't worry about caulking them, just glue them well and if your cuts are straight, you shouldn't have any issues whatsoever.
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post #3 of 37 Old 12-04-2007, 08:39 AM - Thread Starter
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That's a very good point. In fact, the neccessity of sealing the box is altogether a bit more of a nitpick than anything else. I have caulked all the edges except the front so I'll just add a bunch of glue and make sure I clamp it well. I doubt the small amount of air leakage will negatively impact the sound in any way.

Thanks!
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post #4 of 37 Old 12-04-2007, 09:09 AM
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Actually, you don't really want a perfectly sealed box. I know someone that did this with a subwoofer - problem was, it heated up inside and hot air expands, of course... with nowhere to go, it pushed the cone out.

C
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post #5 of 37 Old 12-04-2007, 09:33 AM
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Quote:
Originally Posted by cjd View Post

Actually, you don't really want a perfectly sealed box. I know someone that did this with a subwoofer - problem was, it heated up inside and hot air expands, of course... with nowhere to go, it pushed the cone out.

C

Well, if you are going for a sealed design, you do want the box to be sealed was well as possible, perfectly if you can. The air pressure (and small amounts of heat) are what the enclosure/driver combo is designed for.

I don't have any idea how someone would create enough heat inside the box to blow out a cone unless there was steam and an actual fire.
If the cone blew out, it was becasue of the driver self destructed from abuse, not from heat inside the box.

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post #6 of 37 Old 12-04-2007, 09:43 AM
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Leaks make all kinds of horrible noises, you definitely don't want them in any sub. There are people that drive powerful 18" subs in small boxes with thousands of watts and don't deal with what you mentioned (joe for one, you don't get much beefier than an LMS/CE4k combo unless you get into car stuff)
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post #7 of 37 Old 12-04-2007, 09:53 AM
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Yep, sealed means sealed, not mostly sealed or almost sealed.

If you want a box with holes, go ported/vented.

I like to glue/clamp everything together then go around the inside with caulk or liquid nails just case there is a void where the glue did not seal correctly.
But of course, building the enclosure correctly goes a lot further in the first place.

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post #8 of 37 Old 12-04-2007, 12:13 PM
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Nope. Sealed doesn't mean perfectly sealed. It means nearly perfectly sealed, within reason.

You *can't* if the driver has a phase plug... No double peaks still - it's "sealed" mechanically, even though technically there's an air leak.

It didn't destroy the cone or driver, it just pushed the driver out so its "centered" position changed. Calculate volume change for an air mass and a 30 degree rise (F) in temperature - not at all unreasonable within normal operating parameters. (hint: 6.5% increase in volume) That's from a 70 degree nominal (i.e. room temp) to 100 degree (i.e. body temp...) - it wouldn't even feel warm to you. And especially small sealed systems heat up more than this.

C
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post #9 of 37 Old 12-04-2007, 03:05 PM
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I'm sorry we will have to agree to disagree.

No one designs an enclosure to leak. It is a sealed system and there is simply no reasonable way to heat up the air that much to blow out the cone or distort it. If you could heat up the air THAT much it would simply push the cone a miniscule amount. The voice coil and basket and everything else would melt before there could be enough energy to heat up the air inside that is being surrounded by cool air that is in contact with the enlcosure and ultimately the surroundings. The voice coil, while getting very hot under extreme conditions is soooo small in comparison to the volume of air it would have to heat to that degree. The cone may fail do to some factor including heat, but it will not be becasue the super heated air blew it out. Sorry, It just doesn't happen.

BTW, none of my enclosure leak, that is unless someone drilled a hole in it without me noticing. Many of us are sending thousands of watts into small enclosures. If you had a leak you would hear tremendous amounts of whisting, chiffing and all sort of terrible noises. The smaller the leak the worse it would be.

I have been wrong about a great many things and will gladly admit it if that is the case, but I don't see it happening. I will let others weigh in on it.

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post #10 of 37 Old 12-04-2007, 03:15 PM
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Thats kinda funny, cuz I do impedance tests on my sealed sub builds to ensure that there aren't any leaks. Of course, a completely perfect seal is pretty much impossible, even if you use 2 layers of mdf, caulk and sealant around the driver, but the level of air exchange in such instances won't affect the sound and definitely not the cooling of the box, though I suppose if you have a huge temperature difference between the inside and outside of the box, some of the air may escape over a long period of time, but the air will also be cooling down over a long period of time as well.
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post #11 of 37 Old 12-04-2007, 03:15 PM
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The best way to seal the box is to put a THICK bead of liquid nails on before you nail it together. Watch the glue spread out and you now have to choices. You can let it dry the way it is and sand it off. Or you can take a rag and wipe it. I prefer to wipe it into the wood and give it a light sanding afterwards.

Another way is to use fiberglass resin and paint it over all the joints and the rest of the box.. then light sand so its smooth

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post #12 of 37 Old 12-04-2007, 03:22 PM
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I don't think any of us nail our cabinets together, I could be wrong though. Also, the smoothing, while it looks better, weakens the seal, since you are sealing the inside of the box, I wouldn't worry about how it looks. Also, to the OP, all of this is pretty moot since you are doing a TL design, you will have more air exchange in one listening session than a sealed sub will have over its entire life. Like I said before, just use your glue (liquid nails or similar) and make sure your cuts as perfect as possible, if they are good, you shouldn't have any problems.
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post #13 of 37 Old 12-04-2007, 03:28 PM
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Joe, when he mentions cone blowout, I think he is referring to the resting position of the cone changing over time, not the entire sub being blown out of the cabinet. This can happen over time, but its not something I would loose sleep over, I am not sure what happened to cjd's friend's build that made it blow out, but that has not happened to the sealed sub I built, and it was very well sealed, and it was super tiny (0.7cubes) and took 1500watts.
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post #14 of 37 Old 12-04-2007, 03:29 PM
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Quote:
Originally Posted by jdohman View Post

The best way to seal the box is to put a THICK bead of liquid nails on before you nail it together. Watch the glue spread out and you now have to choices. You can let it dry the way it is and sand it off. Or you can take a rag and wipe it. I prefer to wipe it into the wood and give it a light sanding afterwards.

That's basically what I do. After getting a good seal with glue, screws and clamps, I then coat the inside seams with a bead of liquid nails for added measure. I just smear it in there with a finger to ensure it gets into every crack and void.

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post #15 of 37 Old 12-04-2007, 06:45 PM
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In smaller enclosers where you can't get a calking gun in, I use a glue gun. You can feel the seam with the tip and apply a bead of hot glue that dries in minutes.
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post #16 of 37 Old 12-04-2007, 07:32 PM
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Quote:
Originally Posted by armystud0911 View Post

Joe, when he mentions cone blowout, I think he is referring to the resting position of the cone changing over time, not the entire sub being blown out of the cabinet. This can happen over time, but its not something I would loose sleep over, I am not sure what happened to cjd's friend's build that made it blow out, but that has not happened to the sealed sub I built, and it was very well sealed, and it was super tiny (0.7cubes) and took 1500watts.

Yes, it changed the resting position, but rather dramatically. Long-throw 15" in a 2 cu/ft enclosure. It returned to normal after cooling down. He does marine work, so when he built it sealed, it was sealed. Double o-rings for all the fasteners, the works. You might be surprised how much heat is generated over time while in use. A similar sub I've built in a 2cu/ft sealed box runs about 110 degrees F on the cone surface after a movie. Do the math. Even 5% volume change equates to enough difference to change the resting position of the cone 3/4 of an inch.

The volume change is so small over time that it doesn't take much "leak" to balance this out, while still qualifying as very much sealed. A pinhole would do it. All I'm saying is, if you're using glue on your joints and not skimping out (which would result in dry joints and poor results), the end result should be more than sufficiently sealed. No need to bead every joint beyond that with caulk or similar.

C
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post #17 of 37 Old 12-05-2007, 09:50 AM
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Quote:
Originally Posted by armystud0911 View Post

I don't think any of us nail our cabinets together, I could be wrong though. Also, the smoothing, while it looks better, weakens the seal, since you are sealing the inside of the box, I wouldn't worry about how it looks. Also, to the OP, all of this is pretty moot since you are doing a TL design, you will have more air exchange in one listening session than a sealed sub will have over its entire life. Like I said before, just use your glue (liquid nails or similar) and make sure your cuts as perfect as possible, if they are good, you shouldn't have any problems.

I nail all glue all my cabinets together. The nails only holds it in place until the glue dries. Lets just say I have built probally over 1500 cabinets in the past 4 years alone and never had one come apart on me. A good air nailer and glue will do the same job blue and screws will do. You also do not have to worry about counter sinking pre drilling and if the wood is going to split. If you have not tried it you really must. Once you do you will never go back.

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post #18 of 37 Old 12-05-2007, 11:05 AM - Thread Starter
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There's some interesting discussion here As to my original post, I build almost all of my enclosures with an air nailer and glue, I don't use clamps except to hold things in place while nailing. I don't have a lot of very large clamps that would be necessary for building a full size speaker In the past I've always been able to fit an arm or hand into the cabinet after it was built to finish applying caulk to all the seams. However this is my first TL cabinet and there is no way to even check if the seams are sealing with the glue, much less get any caulk in there.

My cuts were straight and assembly was good with no more than a 1/16" overhang on any of the pieces so I'm going to assume that it's sealed enough.

Thanks all,

Russell
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post #19 of 37 Old 12-05-2007, 02:31 PM
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All of the builds I have done don't use screws or nails, just lots of clamps until the glue dries. I suppose you could use nails, I have just never seen it done around here.
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post #20 of 37 Old 12-05-2007, 07:30 PM
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Quote:
Originally Posted by armystud0911 View Post

All of the builds I have done don't use screws or nails, just lots of clamps until the glue dries. I suppose you could use nails, I have just never seen it done around here.


clamps are going to do pretty much the same thing as nails.

I thought you were saying that you used screws.

The nails just make it easier putting the box together.

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post #21 of 37 Old 12-05-2007, 09:47 PM
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makes since I guess, I just haven't seen it, I suppose If I had a nail gun, I'd give it a try
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post #22 of 37 Old 12-06-2007, 06:59 AM
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Quote:
Originally Posted by armystud0911 View Post

makes since I guess, I just haven't seen it, I suppose If I had a nail gun, I'd give it a try

It does work well to speed thing up as well. You can join the panels and "shoot" them to hold them in place. Sometimes fumbling around with adjusting the clamps and devising ways to hold things can be a real pain. A nail gun can make short work of that process. Anything I don't have to stain/poly I shoot or screw together, along with glue of course.

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post #23 of 37 Old 12-06-2007, 01:54 PM
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I don't have a nail gun but do have a brad nailer. Was thinking about doing that while the glue dries to speed up the process instead of waiting for clamps to be available.

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post #24 of 37 Old 12-06-2007, 02:00 PM
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Are you guys using nails pre-drilling the holes? I've found that unless you pre-drill the nail holes I get a split just about every time you drive one in.

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post #25 of 37 Old 12-06-2007, 03:23 PM
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Originally Posted by impala454 View Post

Are you guys using nails pre-drilling the holes? I've found that unless you pre-drill the nail holes I get a split just about every time you drive one in.

then you are doing something seriously wrong. Or you are using nails that are WAY to big.

I have probally built over 1000 enclosures using my nail gun and never have the wood split.

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post #26 of 37 Old 12-06-2007, 03:24 PM
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Quote:
Originally Posted by Avus_M3 View Post

I don't have a nail gun but do have a brad nailer. Was thinking about doing that while the glue dries to speed up the process instead of waiting for clamps to be available.


That is what we are talking about.

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post #27 of 37 Old 12-06-2007, 03:27 PM
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Doh...good to know. I wonder why more don't use them? Seems like it would drastically speed the time frame up??

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post #28 of 37 Old 12-06-2007, 04:50 PM
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It is just one of those tools that most don't have. I use brads but not 10 penny nails.

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post #29 of 37 Old 12-06-2007, 09:16 PM
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I'm surprised nobody mentioned Gorilla glue yet. The polyurethane glues expand as they cure. This will give you a much more air tight seal and fill the gaps as long as they aren't too wide. They do however need moisture to cure. In the winter we never had very good luck with them. You can take a spray bottle and moisten the edges of the MDF before you glue it together, but it just doesn't seem to cure the same as when there is more humidity. I've seen some wood shops with humidifiers to make these kinds of glue cure better and also to keep static electricity down. Boiling some water does the same thing.

I assemble most everything with 16awg brad nails. I'll typically put on the glue, use clamps to pull everything tight, nail, and then take the clamps off and move on to the next piece. On painted enclosures I will typically just glue and clamp the outside layer of the box. That way I don't have to worry about filling the nail holes.

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post #30 of 37 Old 12-07-2007, 04:47 AM - Thread Starter
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John,

I had thought about Gorilla glue, but in doing some research I was told that because it expands so much, you have to keep your work clamped down. Nails aren't strong enough to keep it in place. Sounds like you've had a different experience?

Humidity won't be a problem for me, I'm in Houston where it's currently 80 degrees and 95% humidity
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