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Kef 107's and ferrofluid

 
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vistisen
Intermediate Contributor 50+


Joined: 01 Sep 2006
Posts: 57
Location: Denmark

PostPosted: Sun May 10, 2015 7:43 pm    Post subject: Kef 107's and ferrofluid Reply with quote

I have just got my tweeters back from the US where they were sent to be refilled with fluid ( the speakers have been in my possession for over 10 years and I don't think they've been looked at since new). What a revelation!
Suddenly vocals have a natural sibilance. I can hear the zing of a slightly loose guitar string against a metal fret. If anyone has Kef's with T33's that you know have not been treated recently, then don't wait, do it $100 upgrade that will astound you. Suddenly the musicians are in the room again, it all sounds so natural Very Happy
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SaSi
Senior Contributor 200+


Joined: 24 Aug 2008
Posts: 223

PostPosted: Thu May 14, 2015 8:03 pm    Post subject: Reply with quote

What was the timbre of the highs before treating the tweeters? Were they dull, too bright, sibilant or muddy?
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vistisen
Intermediate Contributor 50+


Joined: 01 Sep 2006
Posts: 57
Location: Denmark

PostPosted: Fri May 15, 2015 7:09 am    Post subject: Reply with quote

There were two main problems, one is that especially on some modern recordings the treble was very harsh. It spat at you, that seems to be a lot more under control. The other main thing I now realize was missing was the natural 'punctuation' of sound that I did not think had any treble frequencies, but now know they do. I was listening last night to Alison Krauss. The acoustic bass sting plucking actually contains a lot of treble information, and while before I loved my Kef for the weight of the bass, I now hear the instrument in the room. with all its interactions with the air around it. Its difficult to explain. So I guess the answer is that it the subtle treble sounds that were muddy before that are now revealed without it going over the top.

I should add that I use a DEQX PDC2.6 instead of a Kube and that does a good and very precise job of equalizing both the frequencies and the phase of the speakers (and the room) I do not know if the harsh treble I experienced before is all the fault of the source material or the result of the DEQX being too linear,, but it is much less harsh now.
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SaSi
Senior Contributor 200+


Joined: 24 Aug 2008
Posts: 223

PostPosted: Fri May 15, 2015 8:59 pm    Post subject: Reply with quote

Thanks for the feedback. I'm asking because I don't know the condition of the T33s in mine. They sounded too bright in an empty reflective room (workshop) but sound pretty nice in the furnished listening room.

I still, though, find some recordings where the highs are a bit pronounced. Like needing a -3dB roll off. OTOH, with some very good recordings (Jazz and classical) the highs come out fine unequalized.

The heads were not used and stored for years face up in a basement storage room with ambient conditions varying from damp warm to cold. Wonder if that may have caused the ferrofluid to evaporate.
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exkefman
Intermediate Contributor 25+


Joined: 19 Jun 2015
Posts: 25
Location: Cheshire, England

PostPosted: Mon Jun 22, 2015 12:45 am    Post subject: Reply with quote

SaSi wrote:
Thanks for the feedback. I'm asking because I don't know the condition of the T33s in mine. They sounded too bright in an empty reflective room (workshop) but sound pretty nice in the furnished listening room.

I still, though, find some recordings where the highs are a bit pronounced. Like needing a -3dB roll off. OTOH, with some very good recordings (Jazz and classical) the highs come out fine unequalized.

The heads were not used and stored for years face up in a basement storage room with ambient conditions varying from damp warm to cold. Wonder if that may have caused the ferrofluid to evaporate.


Hi,

It's not "unknown" for ferrofluid to dry out over time...and the loss of it can easily affect the sound as there's less dome damping effect.

It is not easy to take apart a T33 to check, as (IIRC), the dome/voice coil assembly is held in place onto the magnet assy by "adhesive tape". And lifting off the dome/vc assy might then mean it doesn't go back in the right position. So, take care if this becomes your best option.

Otherwise, if you find replacement drivers, (of the same type), then they might be of the same vintage and hence have the same issue.
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regards
Tim

(I used to work for KEF from 1988-1995 - you can see my "profile" here: http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=1706)
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