Blog Forums DIY Speakers and Subwoofers What products do you use as sealant?

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    • #12087

      Hi guys,

      I often find, when I am building closed enclosures, that I am chasing air leaks in the end. I do everything I can during the build to ensure that openings are sealed properly, and yet I almost always spend extra time in the end anyways.

      Air leaks identify themselves by sounding like a sort of rattling, on the large beats of the driver (The umf umf sounds are accompanied by something that sounds like rattling wires or something – but its not, its air leaks from somewhere).

      Anyway, my question is, how do you guys seal your enclosures? Is there a good product to use, for around the edges of the speaker driver after screwing it in (from the inside) and for around holes for switches, plugs etc.?

      I’ve been using hot glue to seal around edges etc.

      In my current project, I still have no clue where the rattle is coming from, which is very frustrating.

      All the best,

    • #12089


      There’s a few things I do depending on the circumstance.  The first is make sure you clamp really well during glue up.  Do not skimp on the clamps.  It can make all the difference in the world.  Talking about glue up, make sure to use quality glue.  I typically use titebond II to glue wood or MDF.  But some of you projects use concrete.  For that, I might try something like gorilla glue, which expands to fill in cracks.  It might help fill in those porous areas.  You just need to make sure it doesn’t come out the front of your project and ruin your front baffle.

      Secondly,  You can always seal from the inside.  What does that mean? add a bead of silicone caulk all the way around the internal perimeters.  Fill any area that was glued together.  

      Another thing you can do, with anything you will be painting, it to fill the spots that the mdf or wood was glued together.  What I like to use is Bondo.  It is very strong and if it goes over the whole seam, it should stop the air leak. 

    • #12090


      Thanks! Yes, usually its concrete. On these I usually have the problem when screwing on the front panel. There it seems that the problem is somewhere around the edges of the front panel, where the wood meets the internal mdf frame with the foam strip. Usually that is solved by screwing in the panel very very tight. I haven’t had problem with the concrete, and the holes for connections on the back are sealed with hot glue to keep the air from leaking through, namely the power panel mount.

      However, this project is an all-wood one – boards glued together and carved out
      Up until now I thought the problem was perhaps one of the drivers, not connecting good enough with with the front – I screw the speaker driver in from the inside. Its sealed plenty around the edges, but I didn’t use the little foam inlay that comes with the box, when you buy the speaker driver. What that a mistake? I don’t use it because it is near impossible to make it invisible from when looking from the front. It sticks out here and there, around the hole, seen from the outside.

      I have not considered that I might have air leaking from between the boards, if the clamping has not been sufficient.

      I have been using this type of wood glue

      Does it seem likely to you that it might be from between the boards? I can try to use silicon caulk around all seems?

      Should I try to remove all the hot glue around the connections and drivers, and replace with silicon caulk instead?

    • #12092


      I don’t know anything about that specific wood glue, so I can’t really comment on that.  However, you should be using the rubber gasket that came with the speakers if rear mounting.  That will help fill any small inconsistencies between the wood and the metal frame. 

      Although, I am not completely sure you have an air leak.  You have done more than most to rectify this potential problem.  If it remains, there might be another issue.

    • #12094


      Thanks again! Come to think of it, I think it’s locally produced in Scandinavia, so I understand 🙂 However the brand is good quality in general. 

      Ok I though you might say that, so I’ve prepared myself mentally all day to disassemble the whole thing again if I can’t locate the problem. 

      I don’t know what else it could be. I mean, it’s not the driver I think. I though this once before on another project. But when I remove the back panel, the rattle gets worse until the air move freely from out the back through the big hole, the sound then sucks but the rattle stops. I assume the driver moves the same big motions with or without air tightness, only the sound is affected, therefore I concluded it’s not the driver. Am I on the right track? 

      It might be that it’s difficult for the human ear to locate where exactly the sound is coming from, and it’s really somewhere from out the back. Might be more likely, I don’t know. 

    • #12095


      I think I’ve located the leak! It’s seems to be on the driver I thought it was. What I did was stuff an led strip inside the box and close it up again, light it up and turn off all the lights. There is a little light seeping out of just that driver and nowhere else. 

      If this turns out not to be the problem I will have done a lot of work in vain. Not onto removing all the glue and get of the drivers only to reassemble everything again with the foam gasket. You were right, the gasket is necessary. Wish we’d talked about this a couple of days ago, haha. So stupid and guy like. “Well yeah, I see it in the box there, but I don’t need that”. 

      Anyway, will let you know if that’s the problem or if I am just rambling… 

    • #12096

       😆  True guy fashion! “Gasket? Gasket? We don’t need no stinking gasket!” Lol

      If you still feel the need to seal the box even more, an easy way would be to use the glue to paint the inside. Preferably, you would thin it out just a little – use whatever is recommended to clean up, water, thinner, etc., just enough to make the glue less thick and able to seep into any openings/cracks fairly easy. Almost like decoupage, just not so thick.

    • #12097
      Posted by: @tvor-ceasar

       😆  True guy fashion! “Gasket? Gasket? We don’t need no stinking gasket!” Lol

      Haha!  This made me laugh out loud, literally.

      @kanaaudio that was a great idea with the led strip.  I have never thought of that.  I’ve used that trick before (aka light to find a leak), just never with my speaker building.  Great innovative idea. 

    • #12098


      Thanks, I’ll keep that in mind if I can’t make this work. 
      I’ve always avoided using the foam gasket because it ends up being visible from the front. The diameter of the gasket is just 1-2 mm less than the cutout hole in the front panel. 
      So I’ve been trying to glue in the drivers in addition to the screws, but I think what I’ve been using is too rigid to connect properly with the wood. So I will try to screw them in again and seal with the silicon chaulk as toid said 🙂

      Got everything disassembled last night, so hopefully I’ll cross the finish line sometime this weekend:-)

    • #12099


      Thank you! It feels good to be the one contributing with something on here for a change 🙂

    • #12125

      @123toid @tvor-ceasar

      Thanks for your help with this, I just want to give you an update.

      I ended up not using the foam gasket, because it turned out to be impossible to make it non-visible from the front. It is simply just a few millimeters too little compared to the cutout-hole. For future builds, I will have to get a hole-drill of 75 mm rather than 78 mm for the ND-91 drivers, then everything should fit perfectly.

      Anyway, I removed all the glue etc., and replaced it with a silicon chaulk instead as you said, around the edges of the speaker drivers and other connections penetrating the box. That did the trick. 

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