Hi to all.
I built two birch plywood speakers. I wanted to ask you if any of you have ever used the dynamat internally, to make the box stiffer. I bought this that is similar to the dynamat ...
https://www.reckhorn.net/pages/damping/abx-alubutyl.php
I built two birch plywood speakers. I wanted to ask you if any of you have ever used the dynamat internally, to make the box stiffer. I bought this that is similar to the dynamat ...
https://www.reckhorn.net/pages/damping/abx-alubutyl.php
I think that Dynamat - and similar products - are mainly intended to dampen resonances of metal surfaces in auto installs. In that regard, I've certainly found them to work very well indeed. Note that the products on Reckhorn site are clearly described for damping in cars (trucks)
As for making a birch plywood box stiffer, it's been my experience that the material is inherently quite stiff- certainly as compared to MDF - but if you think more is required, strategic bracing between panels can help, and needn't be extreme.
Of course the next question raised would be exactly what performance parameter you're looking to optimize by stiffening, and good like finding consensus on priorities, or on the methods / materials to achieve them.
As for making a birch plywood box stiffer, it's been my experience that the material is inherently quite stiff- certainly as compared to MDF - but if you think more is required, strategic bracing between panels can help, and needn't be extreme.
Of course the next question raised would be exactly what performance parameter you're looking to optimize by stiffening, and good like finding consensus on priorities, or on the methods / materials to achieve them.
Dynamat and yours have an aluminum layer for reflecting heat in automotive applications. 2mm thickness works on 18ga steel with very high resonant freq, but not enough mass for damping heavier and lower resonant frequency birch. It's also very expensive because of the automotive specialty.
I use roofing membrane. 5mm thick, 1lb/sq ft/$1.
I use roofing membrane. 5mm thick, 1lb/sq ft/$1.
Just a quick thought. By adding roofing material or Dynamat (in layers) you are not adding stiffness. You are adding mass without stiffness and that is the idea. Thin Plywood works well since it is stiff for it’s thickness but not so stiff (like 3/4”) that the resonance is up in the midrange where it can be heard easily.
The extra mass does not change the frequency but it will smear them out and lower the amplitude. Lowering the amplitude is what you are doing and why it works.
As above you can add multiple layers of Dynamat or similar. Or use few layers of thicker material. I have used RAAM mat since I had a lot of it. It works fine in layers. I would suggest 3-4 layers depending on the size of the box. On a bookshelf size I used 3 layers on the sides on a two on the very small top and bottom.
The extra mass does not change the frequency but it will smear them out and lower the amplitude. Lowering the amplitude is what you are doing and why it works.
As above you can add multiple layers of Dynamat or similar. Or use few layers of thicker material. I have used RAAM mat since I had a lot of it. It works fine in layers. I would suggest 3-4 layers depending on the size of the box. On a bookshelf size I used 3 layers on the sides on a two on the very small top and bottom.
Here an interesting article about the importance of bracing and stiffness
Thanks
Myths & Facts about Loudspeaker Cabinets: Identifying Legitimately High Fidelity Designs | Audioholics
Thanks
Myths & Facts about Loudspeaker Cabinets: Identifying Legitimately High Fidelity Designs | Audioholics
Hi, I wanted to tell you my experience on the sound-absorbing material.
in a closed box I replaced the polyester I had previously used, with pure carded wool with long fibers.
The change has been remarkable, now the box no longer booms, as if it were full, with the use of only 50 grams of wool for each cabinet.
in a closed box I replaced the polyester I had previously used, with pure carded wool with long fibers.
The change has been remarkable, now the box no longer booms, as if it were full, with the use of only 50 grams of wool for each cabinet.
I don’t agree with everything said about cabinets in this article. This is contrary to the BBC engineers and it is also country to Kef engineers that developed the LS50.
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