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Dutch Big Bass-reflex CS7 Enclosure

 
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stephen2007
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Joined: 16 Nov 2006
Posts: 4

PostPosted: Mon Jan 01, 2007 9:00 am    Post subject: Dutch Big Bass-reflex CS7 Enclosure Reply with quote

Hi , I'm Olaf Markus and I live in the Netherlands.
I build a pair of the big version of the KEF CS7 enclosure.
This is a 120 liter bass-reflex with a non compromise crossover filter.
The sound is incredible with an open mid and high en a dry and deep bass.

The units are :
B139B SP1044 Constructor
B110A Sp1003 Constructor
And Audax TWO 025

De filter components are :
Audyn cap MKP+
Band inductors
And a zero ohm inductor for the bass.







For more Photo's :
http://www.endgame-babylon.eu/luidsprekers/


Last edited by stephen2007 on Sat May 05, 2007 11:32 am; edited 1 time in total
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proffski
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Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Mon Jan 01, 2007 7:46 pm    Post subject: Big Bass-reflex CS7 Enclosure Reply with quote

Wow, nice work!

Out of interest what is the internal volume in Litres & what size of Port did you use in the design?
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stephen2007
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PostPosted: Mon Jan 01, 2007 9:16 pm    Post subject: Reply with quote

The internal volume is 120 liter, de port is 10 cm diameter an 8 cm long.
The inside of the enclosure is al braced en covered with bitumen.
The damping is wool.
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proffski
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Joined: 22 Aug 2003
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Location: Tewkesbury UK

PostPosted: Tue Jan 02, 2007 5:05 pm    Post subject: 120 Litres Reply with quote

Interesting. I have no parameters for the SP1333 but used them from one of the later SP1044 derivatives instead.

Seems your rnormalised amplitude esponse may be only -8dB at 20Hz!
Group delay and phase response also look reasonably well behaved.

Have you any extra bracing inside this large cabinet?
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stephen2007
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Joined: 16 Nov 2006
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PostPosted: Tue Jan 02, 2007 8:32 pm    Post subject: Reply with quote

Yes , the cabinet is all braced , I'll put some more pictures up soon.





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Almtb
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Joined: 28 Jun 2006
Posts: 6
Location: Bristol

PostPosted: Mon Feb 05, 2007 5:32 pm    Post subject: Reply with quote

Nice job! Very Happy

Is the sensitivity high enough to work well with the Valves amps?

Cheers,

Al
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proffski
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Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Mon Feb 05, 2007 6:23 pm    Post subject: KEF B139 Reflex. Reply with quote

What do the bass transients sound like?
Any overhang on organ notes?

Looks a nice neat tidy job, I'm jealous!
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stephen2007
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Joined: 16 Nov 2006
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PostPosted: Wed Feb 14, 2007 8:52 pm    Post subject: Reply with quote

well, back home again.
i spend a week in the hospital for a back spine operation.

The loudspeakers do work on valve amps but on a not to high volume.
Now I've two Vincent Sp 991 plus class A mono power amps a 35 kilogram each and that combines much better with the loudspeakers Laughing

The bas is tight, fast and clean, a short group delay and no booming sound what so ever.
Everything is in the right balance.
I never heard a contrabass witch such a detail.
Also caused by the large zero Ohm inductor in line with the B139 and the MKP capacitors parallel.

Still every day the sound amazes me.
we have in the meantime compared my loudspeakers with the JM-lab Electra 926 and the difference was huge, the Kef’s were by far the best on the hole frequency range.

I'm very satisfied with this achievement and wouldn’t sell them for 2000 euro if someone would bid it.
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