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calnda cabinets

 
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grayyyt
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PostPosted: Sun Jul 21, 2013 10:51 pm    Post subject: calnda cabinets Reply with quote

I have a pair of Kef Calindas and have a couple questions , I hope someone can satisfy. The inside of the cabinets are lined with foam rubber abt. 1 1/4 in thick. Is that correct for these? Wouldn't the foam lining deter bass as it would lessen the volume of air needed to push the passive radiators? Your help is appreciated. Keith
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audiolabtower
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PostPosted: Sun Jul 21, 2013 10:58 pm    Post subject: Reply with quote

Everything in a Kef speaker is there for a purpose Wink The foam damps standing waves inside the cabinet and reduces main resonance which can give an unpleasant "one note bass" type of thump with no relevance to the music. If anything it flattens the bass and the amount is effectively "tuned" to each enclosure and overall design.
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proffski
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PostPosted: Mon Jul 22, 2013 8:41 am    Post subject: Reply with quote

audiolabtower wrote:
Everything in a Kef speaker is there for a purpose Wink The foam damps standing waves inside the cabinet and reduces main resonance which can give an unpleasant "one note bass" type of thump with no relevance to the music. If anything it flattens the bass and the amount is effectively "tuned" to each enclosure and overall design.


If you look at the physics of it "speaker stuffing" as it is commomly called increases the apparent volume of the enclosure... In this case it would be minimal, but as you correctly say also having other benefits.
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SaSi
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PostPosted: Sun Jul 28, 2013 9:56 am    Post subject: Reply with quote

The foam helps control the standing waves generated inside the enclosure. Keep in mind that the woofer radiates as much inside the enclosure as it does in the room. That's a lot for the small volume of the enclosure and there's a lot of pressure modulation inside the enclosure.

As already stated, stuffing the enclosure with porous foam does increase the effective volume of the enclosure in terms of the effects the volume has (deeper bass for example) as it slows down the sound speed.

To a lesser extent, the foam attenuates the sound coming out of the panels of the enclosure. For that there are usually strips of bitumen material glued and stapled to the center of panels. Unfortunatelly, after 30 yeas, these pieces of bitumen have hardened and no longer perform their task. Actually, I am guessing that hard and brittle as they have become, they resonate instead of dampening resonances.

I have had considerable improvement by glueing such bitumen sheets to the inside of a pair of Carlton III, a design very similar to the Calinda (8" woofer with B139PR). Bass has become much tighter and boxiness (sometimes audible) has decreased to the point it's almost inaudible.
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speakerguru
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PostPosted: Sun Jul 28, 2013 9:49 pm    Post subject: Reply with quote

If you want to get a feel for what the lining achieves, remove the woofer and have someone who's voice you know well, speak to you, while holding the open hole of the cabinet near their mouth. Remove the stuffing and repeat the experiment.
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