SimontY said:
before I made my latest sub enclosure I had the 2x 15's in a sealed enclosure of similar volume but with the drivers on the same side, the difference in bass between the 2 enclosures is impressive, the old one would rock and vibrate slightly (and it was braced pretty well) where this new one doesn't move or vibrate at all.
I think this is all just a design exercise and mostly unnecessary. Even a 750watt sub is only putting 750 watts throughout the entire interior of the box and that is not a lot of force. Even more so, the compression of the air inside a sealed box might change the air pressure inside by 0.1 psi (0.7kPa). That's pretty small considering the box is probably built with 3/4" MDF or ply.
Still, even I want to truly minimize any box flex, so I propose this for big enclosures.
In a sub with anything other than a 1:1 port, the braces have to deal with both compression and tension. Even more so with a sealed box.
Any of the listed solution will work well for tension - dowels, pipe, tube. I will call them all rods. The problem with compression is the it requires lateral strength in the structural of the brace. One was to think of this is to stand on a (non-alcoholic) beer can. It will not crush. However, if your friend pokes the side with a stick and gives it a dent, you will quickly end up standing on a flattened can. It is easy to see how the rods flex when you put them on your knee and bend each end with your hands. This flex nullifies any compression strength in the material.
To give this compression strength back, you can do only two things: 1) Add more material or 2) Use the material over a larger diameter. In practice this would be like using larger diameter rod. For the tube wall thickness doesn't matter much as long as it does not dent to the touch and remains perfectly cylindrical during installation.
Even more effective than increasing the diameter is to do both 1 and 2 in combination. For each brace, use a 3 smaller diameter rod, even pencil sized. Space them apart in a triangle about 25mm center to center and glue them in that way. I like the thru-hole method with glue and cut off at the surface. Very strong and easy. Before gluing them in, cut a number of small spacers with the same 3 holes spaced 1-inch (25mm) apart in a triangle. Set these spaces about 150mm (6") apart along the length of the brace. You can use almost anything for the spacers as they only need to to keep the rods from flexing.
🙂ensen.
Still, even I want to truly minimize any box flex, so I propose this for big enclosures.
In a sub with anything other than a 1:1 port, the braces have to deal with both compression and tension. Even more so with a sealed box.
Any of the listed solution will work well for tension - dowels, pipe, tube. I will call them all rods. The problem with compression is the it requires lateral strength in the structural of the brace. One was to think of this is to stand on a (non-alcoholic) beer can. It will not crush. However, if your friend pokes the side with a stick and gives it a dent, you will quickly end up standing on a flattened can. It is easy to see how the rods flex when you put them on your knee and bend each end with your hands. This flex nullifies any compression strength in the material.
To give this compression strength back, you can do only two things: 1) Add more material or 2) Use the material over a larger diameter. In practice this would be like using larger diameter rod. For the tube wall thickness doesn't matter much as long as it does not dent to the touch and remains perfectly cylindrical during installation.
Even more effective than increasing the diameter is to do both 1 and 2 in combination. For each brace, use a 3 smaller diameter rod, even pencil sized. Space them apart in a triangle about 25mm center to center and glue them in that way. I like the thru-hole method with glue and cut off at the surface. Very strong and easy. Before gluing them in, cut a number of small spacers with the same 3 holes spaced 1-inch (25mm) apart in a triangle. Set these spaces about 150mm (6") apart along the length of the brace. You can use almost anything for the spacers as they only need to to keep the rods from flexing.
🙂ensen.
Encouraging thoughts and ideas... I've got some strips of thin wood I might do some dowel-type bracing with in my speakers, not that they *really* need it, but it all helps 🙂 I'd like to put a piece across each bass chamber - right behind the driver, so I can rest the driver on it. Has anyone ever compared not supporting the driver, to supporting it like this? (I've often read that it's reccommended)
Volenti, its good to hear your newer sub is so superior. I've yet to meet a speaker cabinet that doesn't vibrate to the touch, when playing loudly. I guess push-push is truly the way to go, at least for a sub.
-Simon
Volenti, its good to hear your newer sub is so superior. I've yet to meet a speaker cabinet that doesn't vibrate to the touch, when playing loudly. I guess push-push is truly the way to go, at least for a sub.
-Simon
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