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dsmith
Junior Contributor 20+
Joined: 17 Mar 2010
Posts: 20
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 Posted: Sat May 26, 2012 11:45 am Post subject: Re: Thinking of Stiffening 105.1 BassEnclosure with Ceramic |
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| neddy wrote: | .. hopefully resonances that do exist will be raised beyond the pass band of the bass cabinet.
Adding mass should minimise acoustic breakthrough, though I find it difficult to think that this is that important. Critical to when and if and how I try to improve the midrange enclosure will be the mechanical coupling between the bass cabinets and the midrange enclosure, which I think is much more important than acoustic breakthrough (coupling). One thing at a time though... |
I'm not sure why you make the distinction between "coupling" and breakthrough. All we really care about is radiation from the cabinets, primarily because it only happens in narrow bands of resonance and is audible as coloration. Reducing the Q of the resonances will lower their level and audibility. Driving them less (decoupling) is also worthwhile.
Raising them above the crossover point is possible in a 3 way (not in a 2 way at all), but it is hard work. Harwood and Barlow (see the Colloms book) both showed that thicker cabinet walls raised resonance frequencies without lowering resonance levels and made damping much less effective.
You are falling into the audiophile trap of "stiffer is better".
David S. |
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audiolabtower
VIP Contributor 500+
Joined: 06 Jan 2009
Posts: 686
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| Posted: Sat May 26, 2012 1:16 pm Post subject: |
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B300s.. .Ah I see  I thought the data sheet parameters were the same. |
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neddy
Introductory Contributor
Joined: 08 May 2010
Posts: 8
Location: dublin
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| Posted: Thu Apr 18, 2013 2:02 am Post subject: bass bin 105.1 |
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After much deliberation i have decided to clad my kef 105.1 bass bins with 8 mm porcelain black mirror tiles. I intend to use Bostik timebond as the adhesive.
My question is to you experts is whether there is any argument to change the
lossy connection of the bass unit and its baffle to a more rigid arrangement i.e. replace the foam sealing strips with a stiffer damping material such as bitumen sheet. |
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speakerguru
Über Contributor 1000+
Joined: 18 Nov 2005
Posts: 1192
Location: Green Hut, Tovil
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| Posted: Thu Apr 18, 2013 10:00 am Post subject: |
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I see you've chosen to ignore dsmith's well informed comments. Is this in light of your experience that painted stripes on a car make it go faster?  |
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neddy
Introductory Contributor
Joined: 08 May 2010
Posts: 8
Location: dublin
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| Posted: Thu Apr 18, 2013 3:34 pm Post subject: |
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Is this really such a stupid question? If (I know its a big if) cladding the bass bins raised all resonances above the pass band of the bass bins (400Hz 24db octave) then there would be no need for lossy coupling of the bass unit?
I wholeheartedly agree with D.Smith regarding bass/midrange enclosures. In this case I am not adding that much to the structural rigidity of the bass cabinet, more that I am making the panels more rigid and hopefully adding damping by virtue of the glue used. I accept there is a risk that all I may achieve is raising resonances to an audible level at presumably higher frequencies.
never did try the go faster stripes  |
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