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Closed KEF Concerto?!

 
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Jan Eskildsen
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Joined: 21 Apr 2006
Posts: 2
Location: Bornholm

PostPosted: Fri Apr 21, 2006 10:17 am    Post subject: Closed KEF Concerto?! Reply with quote

Happy to find this site and discussion about classic speakers.
I own to pairs of Rogers LS3/5a, which includes more or less the same units that the Concerto, which of course also have B139.

I have a question but have to tell a little story first. My B139es was bought in London and brought home to be used as drivers in a closed subwoofer - my television was standing on it - and in my "all wall" bookshelf I had 2 Rogers. Unfortunately I didn't get the filter right, so cello and bass shifted from sub to side and vice versa.

Then I saw advertising for the Concerto, and went to a hifi shop.
The guy there told me I could use my B139 and he knew a cabinet maker, so I bought the 2 other speakers from him and cabinets were made. These very good loudspeakers were used since the late 1980'es, but right now I have them stored in the cellar, while I try to work out how to convince my wife, that they should go back to the living room (She likes the Rogers, even they are standing on AB1 basses). We have a lot of books (well, mostly me) and she wants some books to go out, if the speakers are to go in.

You can imagine the shock I got few days ago, when I discovered this site and saw the Concerto as a vented cabinet, since mine is closed! I have never seen it before - and advertising for the speaker kit in my country was not a vented one, but closed. Now I wonder, if I should start experimenting with holes in the back of the cabinet, or I should just go on using them as they are.

Another idea might be to build in the B139 in very flat (narrow) cabinet that could be laid under the sofa, and only use them for bass - and still use the small Rogers, but without AB1?

What is the best material to put into the cabinets to dampen them?
And where to get it?
Excuse me, I'm no technician myself and the questions might look silly, but all answers will be appreciated.

Jan (in Bornholm)
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Jan Eskildsen
Introductory Contributor


Joined: 21 Apr 2006
Posts: 2
Location: Bornholm

PostPosted: Fri Apr 21, 2006 10:20 am    Post subject: Closed KEF Concerto 2 Reply with quote

I forgot, that I have used the loudspeaker at my 50 years birthday, and they easily played up the whole room (by my 2x120 watts Kenwood), which was appr. 10 x 10 x 3 meters, which is equivalent ot the 2800 m3 they are suited for. I still think their sound are very good for most music, but sometimes I could hope for more "nuance" in the bass.
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ColinR
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Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Fri Apr 21, 2006 11:11 am    Post subject: Reply with quote

The KEF specification for the B139B states "closed box 30-60 litre" and "reflex 60-140 litre" so you've got a pretty nice pair of speakers with tight, but not grossly extended bass. The Cantata and CS7 use a closed box of ~70 litre btw, so leave 'em alone Very Happy .

Regarding crossovers pinch the bass section from the CS7 if you want to run a passive bass section with your LS animals. The full "Auskef" (Falcon No. 53) if you want to retain your "Concerto" boxes.

For subs with KEF units an active Bassett/Coffin (see t-linespeakers.org), or this dipole design half way down the page may suit.

http://www.tech-diy.com/Dipol-Subwoofer.pdf


Damping materials such a Deadsheet, passive and active sub crossovers are available from Falcon Acoustics www.falcon-acoustics.co.uk

One cautionary note, most classical sub-bass designs are usually inferior to the cheap £100 Yamaha subs bought from discount retailers like Richer Sounds Sad .
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