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rebuy

Cabinet Damping

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I had to remove my drivers for having work done and got a good look

at the insides---I was surprised at what I saw.

 

The cabinets have good internal bracing.

 

The cabinets were damped in two areas

There was about a 6 inch area behind the lower Mid/Bass driver that has damping material.

There is damping material on the bottom of the cabinet---And that's all.

The rest of the cabinet is bare---I'm not planning on adding any material because

I'm not going to second guess the designers design.

I like the speakers sound--I was just surprised at the amount of material in the cabinet.

Are yours damped the same way?

Edited by rebuy

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You didn't say what cabinets you have.  :)

 

I have Klipsch CF-4's.  They put two pieces of 3/4 foam together and lay them loosely in the cabinet.

 

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I have F 20 cabinets that are about 39 inches high and 15 deep and 8 inches wide.

My speakers do not have that much material--or that type.

Edited by rebuy

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Here is a picture of a retro brace job done on my Heresy 3 cabinets done with white oak 3/4" strapping for greatest structural strength wile taking up the least amount of precious cabinet volume in this already undersized cabinet. Every seam of the cabinet now has a 3/4" baton of white oak and each panel is braced length wise along its centre with the same 3/4" oak brace you can see the front to back baffle braces. These cabinets are now ultra solid. This all takes care of the mechanical bracing/stiffening and for internal acoustical damping (which increased apparent internal volume as far as the woofer is concerned) the cabinets are packed to about 95% solid with high density fiberglass which is positioned on edge relative to the woofer to further enhance acoustic absorption of back radiated woofer output (this makes a significant difference)the cabinet is totally air tight as a result of the oak strapping mounted in the seams. There is also some photos of the inside of my Quartet cabinets braced with 3/4", ply the same system of braces and stringers is used to tie all the cabinet panels together. There is a horizontal brace installed both above and below the passive of the Quartet (on the rear baffle) and one above and below the woofer on the front baffle as well, these are important to minimize baffle flex.

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Edited by moray james
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The Heresy is an airtight Speaker--Acoustic Suspension?

And did I read right that it is 95% full of fiberglass?

 

Of course mine--like many here is a Bass Reflex design as you know.

When they damped this speaker behind the lower Mid/ Bass driver--they used

a few inches of material with air space behind it--I assume for Air Flow from the driver above it.

Then some material on the base of the speaker---the rest of the speaker is bare walls.

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Yes the Heresy is a sealed cabinet (all Heresy are totally sealed including the Heresy ll and the Heresy lll) design which results with a 12db per octave roll off below the tuning frequency. Stock Heresy do not use ANY internal acoustic damping material, this was an intentional choice made by PWK but I find that the resulting trade offs of installing the correct form of damping material far out weigh not using any as I achieve better bass weight impact and extension with the inclusion of the high density fiberglass damping material. There are professional versions of the Heresy which are reflex loaded but they have poor bass extension by comparison to the Heresy it is the higher tuning of the pro reflex version which allows them to still have some bass output but is mostly to get them to play louder. With a reflex design there MUST be open cavity volume (which resonates) to optimally couple effectively between the woofer and the vent. It is the woofer that drives the vent into resonance and it is then the vent that is tuned to resonate to control the woofers fundamental resonance within the cabinet. Hope this helps. Best regards Moray James.

Edited by moray james
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I'm surprised that stock original Hersery's had no internal damping in the same way mine has very little.

Then again--I really like the way the speaker sounds that's why I would not add any more.

I guess the damping adds to the voicing of the speaker.

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I have been pondering this before I put my speakers back together--

Since it's only damped in two places--would it be beneficial to put a layer of

damping on the back wall behind the second Mid/woofer or just leave it alone?

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I have been pondering this before I put my speakers back together--

Since it's only damped in two places--would it be beneficial to put a layer of

damping on the back wall behind the second Mid/woofer or just leave it alone?

You could experiment. If they're not too had to get inside, add that piece in back like you mentioned in only one speaker, then compare it to the other speaker. See if you can hear a difference. But it could be like you said, it's hard to second guess the engineers.

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With just one piece--I would not expect to hear a difference--

The damping material would just be there to absorb the backwave from the second driver.

Otherwise-they sound good for us.

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My KG-4's have foam from top to bottom on both sides. They are open through the middle, expected I'd think considering the passive radiator design. I'd never seen foam inside a speaker before. Fiberglass, wool batting, poly batting, never foam. In contrast, a small set of Infinity's was stuffed, and I mean stuffed tight with poly.batting.

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