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Kef 105.4 crossover refurbish & new bascabinets (p-6)
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audiolabtower
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PostPosted: Wed Apr 22, 2015 10:45 am    Post subject: Reply with quote

Very good job - they look like mini 107s ! Smile
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willem-57
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PostPosted: Wed Apr 22, 2015 12:24 pm    Post subject: Reply with quote

proffski & audiolabtower, thx for your reaction's! Yes it looks that they where manufactered alongside the RR107, only the compact version of it.Very Happy
Measurements are: 1090h x 276w x 306d mm (42.9 x 10.8 x 12 inches)
Kef RR107: 1165h x 330w x 448d mm (45.9 x 13 x 17.6 inches)
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willem-57
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PostPosted: Sun Apr 26, 2015 3:39 pm    Post subject: Reply with quote

Replaced the old cross bolds with inbus bolds, mutch better !

Tried also new and other filling material that i made from an piece of latex in combination with BAF. I have put it in the lower chambers and have a little deeper (or more?) bas now. I will now leave it because the sound is very nice now, a good balance between the bascabinet and the heads.

Maybe i also can improve the heads, i have read that in the RR107 Kef redesigned the heads and has put something in or on the insides of the heads, who knows more about this?

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willem-57
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PostPosted: Mon Apr 27, 2015 6:50 am    Post subject: Reply with quote

I found this in a article on stereophile about the RR107 headunit: The head assembly swivels at the neck, allowing the mid and treble units to be toed-in to maintain a good stereo image when the main enclosure is placed square against a wall. The rounded shape of the 105 head has been retained in order to minimize treble diffraction effects, which can smear or defocus the stereo image. Otherwise, the head enclosure has been re-engineered to increase its rigidity, and to slightly increase the cavity volume. A mineral-loaded polymer "goop" is injected into the cavity walls of the head enclosure for damping purposes.
What i wanna know is: from what material(s) is that mineral-loaded polymer "goop" made off?
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willem-57
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PostPosted: Mon Apr 27, 2015 7:09 am    Post subject: Reply with quote

Here's picture from the topic on Audio Karma from another Kef 105.4 owner, you can see the hollow 'walls' of the 105.4 head. Now i must know from what the 'goop' of Kef is made off, or otherwise, should i fill this gavity (partly) with what .... Question

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speakerguru
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PostPosted: Mon Apr 27, 2015 8:32 am    Post subject: Reply with quote

willem-57 wrote:
... you can see the hollow 'walls' of the 105.4 head...

Isn't that hollow where the bracket, which allows you to mount, swivel and rotate the head, goes? If you fill it, the head will be fixed, won't it?
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willem-57
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PostPosted: Mon Apr 27, 2015 8:57 am    Post subject: Reply with quote

Off course, i did not think about that Laughing
But maybe you know what the 107 head update was?
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speakerguru
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PostPosted: Mon Apr 27, 2015 4:49 pm    Post subject: Reply with quote

willem-57 wrote:
But maybe you know what the 107 head update was?

No. Sorry, I don't recall any head update.
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willem-57
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PostPosted: Tue Apr 28, 2015 10:03 am    Post subject: Reply with quote

Maybe the update of the head was only small and not so important, so at the moment i leave it or maybe someone else can tell more about this.

As i wrote earlier about the damping materials, here's a few pictures of the latex/baf damping i'm making for the upper cabinets.



Last edited by willem-57 on Sat Dec 03, 2016 10:08 am; edited 1 time in total
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SaSi
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PostPosted: Wed Apr 29, 2015 12:23 am    Post subject: Reply with quote

The latex "skeleton" looks like closed cell material. If so, it will seriously lower the effective enclosure volume and you will notice a significant bump in the bass with a lower cutoff frequency. May create a "hole" in the upper bass.
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willem-57
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PostPosted: Wed Apr 29, 2015 6:32 am    Post subject: Reply with quote

Thx for your reaction, but no, this is a open cell material, you can blow trough it. I know that's important, otherwise it will not work.
In my work i have to do with these materials (matrasses etc.). There is also a closed version, they call it here nasa matrasses or memoryfoam, that one you should never use for this purpose.

Or the old way, simple polyether foam, enough here:
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SaSi
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PostPosted: Wed Apr 29, 2015 5:17 pm    Post subject: Reply with quote

Then you should be fine. Experiment and let us know.
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willem-57
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PostPosted: Thu Apr 30, 2015 1:12 pm    Post subject: Reply with quote

SaSi wrote:
The latex "skeleton" looks like closed cell material. If so, it will seriously lower the effective enclosure volume and you will notice a significant bump in the bass with a lower cutoff frequency. May create a "hole" in the upper bass.


You where right! These also give a slight bump in the bass region, so i have now put the 'ordinary' poly foam instead and the bump is gone. At the moment the sound is again mutch more like the original rr105.4 design. Only the bass is more tight than with the old twin configuration, maybe because each woofer has now it's own chamber?
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willem-57
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PostPosted: Sun May 10, 2015 10:33 am    Post subject: Reply with quote

Found an article about bracing the speakercabinet:
Myth #3: Less cabinet bracing is better because it lowers resonant frequency and audibility
It is argued that if too much bracing is applied, a higher resonant point will result making any cabinet resonances more audible. While it is true that a higher cabinet resonance at a given SPL is going to be more audible (dismissing the possibility that that resonance will ever be over 3.5 kHz) the reality is that the physical coupling of the speaker to the cabinet is going to make frequencies accompanied by higher excursions (read lower frequencies) more problematic and more likely to result in panel excitation than a high Q resonance at a higher frequency. A stiffer cabinet will simply color the sound less. PERIOD. Less glue, less staples, less screws, and/or less bracing and less effort go into a cheaper cabinet making the enterprise more profitable at a given price point. It is a much faster process to throw the cabinet together quickly than to take the time to do it right. The last and final bonus of that approach is the reduction in weight, which is always going to reduce the cost of shipping.

http://www.audioholics.com/loudspeaker-design/loudspeaker-cabinets
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proffski
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PostPosted: Sun May 10, 2015 4:44 pm    Post subject: Reply with quote

Agreed! Forgive this chaps shyness, the video is most illuminating!

Link: http://www.bowers-wilkins.eu/Discover/Discover/Technologies/Matrix.html

Link: https://www.youtube.com/watch?v=IOnbkyjfQOI
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