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Triamped system with B200/B110/T27

 
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lasser
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Joined: 25 Dec 2013
Posts: 3
Location: Stockholm, Sweden

PostPosted: Thu Dec 26, 2013 9:29 pm    Post subject: Triamped system with B200/B110/T27 Reply with quote

Hello,

being a new poster on this forum, I would like to contribute with my triamped system using the classical KEF drivers B200, B110 and T27.

http://techtalk.parts-express.com/album.php?albumid=485

Please comment on this system. More info on the PE board (search for my posts if you want more info and see the comments)

Best regards//lasse
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SaSi
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Joined: 24 Aug 2008
Posts: 223

PostPosted: Tue Dec 31, 2013 10:27 am    Post subject: Reply with quote

Hello and welcome.

What version of the B200 are you using? There are a few I can recall (SP1014, 1022, 1039, 1063) in this shape.

I am sceptical about the shape of the frame of the baffle around the drivers. Supposedly, you don't want to have anything protruding around the drivers as it can be a source of diffraction. That said, the R104 is just like that...

Edit: OK, after looking at all the pictures it shows it's an SP1014.
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audiolabtower
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Joined: 06 Jan 2009
Posts: 544

PostPosted: Tue Dec 31, 2013 12:42 pm    Post subject: Reply with quote

I agree with SaSi about the possible diffraction, the Ref 104 was not quite so depressed as your picture I seem to remember. However I have seen research showing that the inset increases the enclosure rigidity compared to flush baffle, so as everything in speaker design it is a compromise.

You can get a sheet of closed cell black foam and surround the tweeter with a cutout for the T27 under the grill to stop HF waves travelling across the baffle, hitting the edge and reflecting back to interfere with the direct sound at source and spoiling the stereo image. If you have seen pictures of the LS3/5a without grill it had a felt ring round the T27 for that exact reason.
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speakerguru
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Joined: 18 Nov 2005
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PostPosted: Tue Dec 31, 2013 2:45 pm    Post subject: Reply with quote

audiolabtower wrote:
.... the Ref 104 was not quite so depressed as your picture I seem to remember...


FYI, all the design work on Model 104 was done using a cabinet with the picture frame edges sawn off and taped over. When I asked about this (I had just joined KEF), I was told that is was easier to see what what going on without the cabinet edge diffraction but that, although you could measure the diffraction effect, you could not hear the difference.

Another example of the brain not hearing what a microphone measures?
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lasser
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Joined: 25 Dec 2013
Posts: 3
Location: Stockholm, Sweden

PostPosted: Tue Dec 31, 2013 3:17 pm    Post subject: Tanks for the feedback! Reply with quote

Hi all,

and thanks for the feedback.

Yes, I gather that the design of the edges around the baffle could be better from a strict SQ Point-of wiew but, as mentioned, all designs are results of a lot of compromises. In this case, the speaker system (and the cabinet with amps, CD and more) are in my (and my wifes) bedroom acting as a "second system". There was a strong signal (loud and clear) that this system should be nice to look at and that led me to that design where the drivers (not very beautiful to my wifes eye...) are not showing.

If you look in the other folders on the web-page in the original post, showing other speaker-systems of my design, you see that there is a few that have baffles with rounded edges.

http://techtalk.parts-express.com/album.php?u=6127

The suggestion with foam around the T27 is definiely Worth looking in to. Has anyone any measurements of the T27 with/without foam to share?

Best regards//lasse
Stockholm, Sweden
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lasser
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Joined: 25 Dec 2013
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Location: Stockholm, Sweden

PostPosted: Mon Jan 06, 2014 12:38 pm    Post subject: Reply with quote

Hi again,

I´m a bit curious what you think (apart from baffle edges and an idea on felt around the tweeter) as there isn´t very common to see DIY-efforts with old KEF-drivers around on the net.

-Is this the first design around with this driver-combination?
-What do you think of the XO? Perhaps there is a better one for T27/B100? (this is "KEF Coda") If so what do you suggest?
-Has anyone else tried triamping? Percieved benefits?

Best regards//lasse
Stockholm, Sweden
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proffski
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Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Mon Jan 06, 2014 1:03 pm    Post subject: Reply with quote

Tri-amping with correct equalisation for the drivers worked wonders for one of my projects. Also concentric felt rings on T27s.
You will have to browse here:
http://s891.photobucket.com/user/AndyGoloskof/library/?start=all#/user/AndyGoloskof/library/?start=all&page=4&_suid=1389009607287010784693623995045

Click on the pictures for larger view, some are scanned from prints so quality is poor. Feel free to browse.
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