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KEF Carina II filling/wadding and damping

 
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ED
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Joined: 08 Jul 2014
Posts: 5

PostPosted: Sun Jul 13, 2014 3:36 pm    Post subject: KEF Carina II filling/wadding and damping Reply with quote

Hello,
I recently acquiered a pair of Carinas II and I'm very happy with them, they sound very good to me! but I'd like to make the most of them if there's room for improvement. I'm a total begginer on this subject but first thing that came to mind is the inner filling of the boxes, is it worth improving it? There is some white filling not too densely packed... Is it worth improving damping with "Dedshete" or similiar materials glued to the inside surfaces (as described in the Constructor series instructions) and then substituting the stock white filling with something different? will there be any gains from this?
Thanks
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speakerguru
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Joined: 18 Nov 2005
Posts: 954
Location: Green Hut, Tovil

PostPosted: Tue Jul 15, 2014 8:31 am    Post subject: Reply with quote

Carina was a budget model built to a price. Like most wooden boxes, more damping would reduce the output from resonant vibrating panels. The BAF wadding is OK; no better or worse than foam pads.
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ED
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Joined: 08 Jul 2014
Posts: 5

PostPosted: Thu Jul 17, 2014 10:14 pm    Post subject: Reply with quote

Thanks Smile
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SaSi
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Joined: 24 Aug 2008
Posts: 223

PostPosted: Sat Jul 26, 2014 8:15 am    Post subject: Reply with quote

A couple of years ago I made an experiment to measure the effect of bitumen sheets to the inside of the enclosure.

I built a 190lt enclosure (approx. 90x45x60cm) with 3 braces across the height. The enclosure was made so that the woofer (a B300) was mounted in a small 20lt subenclosure firing inside the cabinet. The 20lt sub-enclosure gave a pretty high Q causing a rather significant boom in the low frequencies, right where the resonance of the box enclosure was.

I padded the inside of the 190lt cabinet with 3mm of bitumen, 6mm and then 9mm of pads, all along the inside of the panels.

In reality, if resonance is what you want to kill, you only need to cover the center half of the surface of each panel. But I was going for that plus soundproofing the enclosure.

The short version of the results was:
No padding whatsoever resulted in the woofer being heard with enough detail (remember it was fully enclosed in the large cabinet).
3mm of padding made some significant reduction in levels, 6mm some more and 9mm a little bit more, bringing the output level to the point it was more or less at the same level as ambient noise in the measurement environment.

The Carina are not as large boxes so I would suggest that 6mm would be more than enough to deaden the box vibration and soundproof them.

Remember: A woofer radiates to the back (inside the box) as much as it does to the front. So the box needs to be able to not only provide a spring loading to it but also absorb the rear firing energy. A bit of foam here and there or even along the inner surface isn't enough to do this.

Pasting 6mm of bitumen sheets across the inner panels all round will give you a much heavier unit that should feel much more substantial to anyone handling it.

And will sound pretty much better.
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ED
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Joined: 08 Jul 2014
Posts: 5

PostPosted: Sat Jul 26, 2014 5:19 pm    Post subject: Reply with quote

Great, thanks, very informative answer!
I will try to experiment with that
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