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Multi-Way Conventional loudspeakers with crossovers

constrained layer damping with MDF and Ply
constrained layer damping with MDF and Ply
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Old 14th February 2020, 07:37 PM   #311
tmuikku is offline tmuikku  Finland
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The piston/cylinder analogy Earl wrote would have 4 times the shearing area than two rods side by side like you've modeled. Piston/cylinder approach raises questions like: How to make the cylinders, plywood? how to assemble the actual box with construction like that?
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Old 14th February 2020, 07:38 PM   #312
marcus1 is offline marcus1
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That's a lot clearer. How would the middle of the blue cross brace(s) (of the legs) be connected together? Are they glued as well or connected together with screws or the like?

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Originally Posted by Arnandsway View Post
4th time the charm?


I made the cross brace in blue so you can see that the other legs/fingers (in white) are connected to the panels.


I also widened the connecting surfaces of the legs. Because in my thinking this would make it more rigid. Hopefully it isn't too confusing.
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Old 14th February 2020, 09:27 PM   #313
gedlee is offline gedlee  United States
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Yea, that's right. The brace needs to be "rigid enough", but rigidity is not what you want, it's damping. The Shore hardness will determine the stiffness far more that the legs or the attachment. So personally, I would just use straight legs, no flare. I don't see it doing anything.
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Old 14th February 2020, 09:31 PM   #314
gedlee is offline gedlee  United States
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Originally Posted by tmuikku View Post
The piston/cylinder analogy Earl wrote would have 4 times the shearing area than two rods side by side like you've modeled. Piston/cylinder approach raises questions like: How to make the cylinders, plywood? how to assemble the actual box with construction like that?
I don't actually use tubes, I use square rods just like shown.

I make the piece separately and glue it in after the enclosure is assembled.

Overkill is not good engineering.
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Old 15th February 2020, 05:46 AM   #315
ScottG is offline ScottG  United States
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Overkill is not good engineering.
-it's excellent marketing though!
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Old 15th February 2020, 06:52 PM   #316
gedlee is offline gedlee  United States
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I make the piece separately and glue it in after the enclosure is assembled.
But my piece is only a cross in 2D, not 3D, so placing it isn't a problem. With a 3D one that could be tricky. In my speakers I only damp the front-back and sides. Top and bottom are pretty small and one in on the ground, so I don't worry about those.
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Old 15th February 2020, 08:08 PM   #317
drpro is offline drpro  United States
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constrained layer damping with MDF and Ply
An interested reader with a question. If I understand correctly the pieces are glued along the long axis, the point where they intersect in the middle of the enclosure and glue at the ends where they touch the walls of the enclosure.

And it's not glue but this IE40 damping material?
Thanks
David
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Old 15th February 2020, 08:39 PM   #318
gedlee is offline gedlee  United States
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Yes, the IE40 is applied all along the braces. I usually use a hard glue to attach them to the walls, and a hard glue at the center. But no where should one be able to follow a path through any hard mount from any side to any side or the middle joint. All path must be damped.
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Old 15th February 2020, 10:31 PM   #319
drpro is offline drpro  United States
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constrained layer damping with MDF and Ply
Thank you Earl for the explanation.
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Old 15th February 2020, 11:41 PM   #320
gedlee is offline gedlee  United States
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Here is the thing with IE40, it is very thin and runs out all over. The filler helps - a lot - but it still runs. So I ended up making a mold that I could basically cast the pieces into thus filling up and coating all the surfaces. This was about the best method that I found. The piece when it was done was dead, dead, dead.
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