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Heresy cabinet damping (again)


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Hello,

A lot of posts have been written about damping the Heresy's cabinet and it seems that almost everybody consider it as a bad thing. But all those experience were an attempt to damp the load of the woofer.

I recently read a very interesting article about parasitic vibrations in speakers enclosures and I'm thinking about damping the cabinet walls (maybe with Dynamat or bitumen sheets). I already replaced the back wall with thicker plywood with good results, so I'm wondering if damping the walls could be as good. Does anybody here tried such a mod?

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stiffening and cross bracing will do more for you than attempting to damp high Q panel vibrations with thin layers of goo. Split the panels down their long axis with a good stiff on edge brace then tie the panels together with strapping from brace to brace, front to back side to side top to bottom. At this point there will no longer be and serious panel resonances within the passband of the driver. You could then experiment with some damping on the panel walls to see what you think. Hope this is of interest. Best regards Moray James.

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like james said. first put in a cross brace (front to back, sides to sides). brace should be between the horn and woofer.

second, go grab a bag of the poly-fill sheet from walmart and glue them to the walls. also remember to put a sheet on top of the brace.

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Thanks for your answers.

Stiffening the walls seems to be a good idea. It must be worth the work. Nevertheless, I think that stiffening a cabinet can move parasitical vibrations to an upper frequencies, so maybe it could be usefull to put Dynamat after the bracing the enclosure.

second, go grab a bag of the poly-fill sheet from walmart and glue them to the walls. also remember to put a sheet on top of the brace.

Your idea seems logical, as in a closed enclosure, the rear wave of the speakers has to be totally absorbed (and this how most closed speakers are made). But it seems that lots of people who tried this on their Heresy didn't like the result. So I'm quite hesitant.

Did you stuff your cabinet with polyfill?

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I'm thinking about damping the cabinet walls (maybe with Dynamat or bitumen sheets).


Dynamat and materials like that are meant to damp vibrations/resonances in metal car body panels. They can also be helpful with metal horns like K400s, but wooden panels already have more inherent damping than metal panels, so the benefits of applying it would be limited.
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Another "cheat" for the H-I is to remove the original 1/2" rear panel and replace it with a 3/4" panel (45 degree router on the edges to bring the edge back to 1/2" thick takes care of the appearance issues...). Another "cheat" is to throw a couple of 3 pound "soft weights" (SCUBA) on the floor of the cabinet, up against the side panels. That'll really stop alot of unwanted resonance, vibrations, etc.....

[H]

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I'm thinking about damping the cabinet walls (maybe with Dynamat or bitumen sheets).


Dynamat
and materials like that are meant to damp vibrations/resonances in
metal car body panels. They can also be helpful with metal horns like
K400s, but wooden panels already have more inherent damping than metal
panels, so the benefits of applying it would be limited.


I use the word "Dynamat" as a generic term. I'm not sure I will use this stuff. Bitumen sheets or material used in house buildind to damp walls or wooden doors could be interesting. I have some scrap of Dynamat, I will try it on some plywood board to see how it manage with vibrations.

Another "cheat" for the H-I is to remove the original 1/2" rear panel and replace it with a 3/4" panel (45 degree router on the edges to bring the edge back to 1/2" thick takes care of the appearance issues...). Another "cheat" is to throw a couple of 3 pound "soft weights" (SCUBA) on the floor of the cabinet, up against the side panels. That'll really stop alot of unwanted resonance, vibrations, etc.....

Cool

I already replaced the back panel with a thicker one (19mm plywood). I can feel the difference when I put my hand on it. And I can hear it with a clearer, less draft (I'm not sure of the word) bass sound. A definitely essential mod.

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