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Old 10th September 2012, 03:31 AM   #1
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Join Date: Jun 2012
Question KEF 105/3 Restoration

Hello all! This is my first post and I am looking for a little help and advice.
Seems there are some folks here that used to work for KEF back in the day, so I'm hoping they might chime in.

I recently acquired a pair of 105/3's in fairly good condition. As they are, they sound fantastic! However, I have noticed a few things which I think need to be addressed:


1- The center woofer donuts have been replaced, but not with the typical foam ones you see on the web. They are some kind of woven fiber/fabric. They seem to be OK in the sense that they keep particles out of the coils, but there is no spring/tension to them. Also, one of them is not even attached to the rim of the plastic sheath around the rod. I have done this repair on a set of 104/2's using the foam donuts and it is my guess that they not only provide protection from dust, but also keep the woofers "suspended" so the coils don't bottom out. These speakers are much easier to work on than the 104/2's, so I am thinking it would be best to replace them with a set of standard foam donuts.


2- The tweeters were replaced and must have been within the time that KEF still offered originals, as they are NT25's. However, the job must not have gone smoothly, as evidenced by the fact that one of the UNI-Q midrange drivers is missing the plastic washer/guide that centers the tweeter. It has been replaced with a large metal washer which is glued in place. A hole was drilled through the edge of the washer to allow the wires to pass through. It works, but it 'aint pretty. Aside from all this, the question I have is, were these tweeters subject to the same issue with dried-up Ferrofluid as the T33's in the 104/2's? They do sound a little dim to me. I spoke with KEF in NJ and they do offer replacement tweeters, but they are a substitute part. Can anyone offer an opinion on the substitute tweeters?


3- One of the UNI-Q midranges has a slight voice-coil rub when depressed. You can hear a slight "tik-tik-tik", as if there is a bur or some particle rubbing on the coil wraps as it moves in and out. It does not appear to cause any audible problems, but I figure if I am doing a restoration, I may as well try to correct this. I have already rotated the driver in case it was caused by sag, so we'll see if that helps any. KEF no longer has any originals, nor do they even offer a substitute part at this point. However, they do offer a reconing service. Has anyone here ever used their service for something like this?


4- The bass response, while tight and accurate, is a bit lacking in slam. I have read mixed things about using the KUBE in that it can cloud the wonderful midrange. I believe the KEF museum makes note that the KUBE 200 was the one to be used with the 105/3. I have also read that it can be used in a bi-amp setup on the LF inputs only. This sounds like the best bet. Has anyone used this combination?


As I figure I'd have to spend a boatload of money to get anywhere near the quality of the 105/3's in a modern speaker, I think a couple hundred in parts and a Saturday afternoon would be worth it.


I would be most grateful for any tips or knowledge with regards to working on these speakers, or anything in general that would be helpful, as well as any other alternate resources for parts or places that specialize in servicing KEF.


Thank you for reading!
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Old 10th September 2012, 09:12 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

Biamping with the Kube only on the bass section is clearly a way to avoid
having some basic opamp circuitry in series with the mid and treble.

I really can't see the central doughnuts having any real effect suspension wise.
They could easily be omitted AFAICT (top unit), they don't do the spiders job.

rgds, sreten.
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Old 10th September 2012, 09:25 PM   #3
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Location: Queensland Australia
Hi rdeckard2019.
Another site that may prove useful to you is one dedicated to KEF units. If you Google "hifiloudspeakers" the site turns up very early (if not the first non-commercial one). A lot of v. serious KEF 'afficionados' hang out there in the forum section. They might be helpful.
Cheers, Jonathan
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Old 11th September 2012, 01:38 PM   #4
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Quote:
Originally Posted by sreten View Post
Hi,

Biamping with the Kube only on the bass section is clearly a way to avoid
having some basic opamp circuitry in series with the mid and treble.

I really can't see the central doughnuts having any real effect suspension wise.
They could easily be omitted AFAICT (top unit), they don't do the spiders job.

rgds, sreten.
Good point re: the spider, just wasn't sure if the foam donuts did anything but keep particles out of the coil. Thanks for the info!
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Old 11th September 2012, 01:40 PM   #5
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Join Date: Jun 2012
Quote:
Originally Posted by Jonathan Bright View Post
Hi rdeckard2019.
Another site that may prove useful to you is one dedicated to KEF units. If you Google "hifiloudspeakers" the site turns up very early (if not the first non-commercial one). A lot of v. serious KEF 'afficionados' hang out there in the forum section. They might be helpful.
Cheers, Jonathan
Much appreciated! I have now posted over there as well and gotten some good info already.
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Old 8th October 2012, 11:44 AM   #6
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Join Date: Oct 2012
Hi rdeckard2019,

I recently purchased a mint condition pair of KEF 105/3's here in the UK. They required bass driver refoaming (doughnut and surrounds) which I purchased from AudioFriends in NL. I speak Dutch so I am happy to translate any of their instructions of repairs if needed. I took photos every step of the way with my repair so I am happy to assist anyone with such a job on these fine speakers. I'm in need of a Kube 200 and I find schematics here but that is a job probably beyond me, so I'm looking to either buy a Kube 200 from someone or would buy a unit built by someone with quality components. I like the idea of bi-ampification to retain the brilliant midrange. I'm waiting on an authorisation code from the admin to join the HiFiLoudspeaker forum. Let me know if I can help you in any way.

Cheers, Zak
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Old 15th December 2012, 01:02 AM   #7
nat8808 is offline nat8808  United Kingdom
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Join Date: Aug 2010
Location: London
Quote:
Originally Posted by sreten View Post
Hi,

Biamping with the Kube only on the bass section is clearly a way to avoid
having some basic opamp circuitry in series with the mid and treble.

I really can't see the central doughnuts having any real effect suspension wise.
They could easily be omitted AFAICT (top unit), they don't do the spiders job.

rgds, sreten.
I'm relatively sure I was told by Kef spares that the cetre doughnuts don't have a suspension effect - they are just for keeping out dust just as you assume. It's a vague memory and I actually called them to ask about replacement tweeters on some 107s.
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Old 15th February 2013, 01:38 AM   #8
milosnj is offline milosnj  Serbia
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Join Date: Feb 2013
Default kef 105/3

Hello Zak,

Could you please send myself fotos about reparing 105/3.

Regards,
Milos
Beograd, Serbia

Quote:
Originally Posted by zaktech View Post
Hi rdeckard2019,

I recently purchased a mint condition pair of KEF 105/3's here in the UK. They required bass driver refoaming (doughnut and surrounds) which I purchased from AudioFriends in NL. I speak Dutch so I am happy to translate any of their instructions of repairs if needed. I took photos every step of the way with my repair so I am happy to assist anyone with such a job on these fine speakers. I'm in need of a Kube 200 and I find schematics here but that is a job probably beyond me, so I'm looking to either buy a Kube 200 from someone or would buy a unit built by someone with quality components. I like the idea of bi-ampification to retain the brilliant midrange. I'm waiting on an authorisation code from the admin to join the HiFiLoudspeaker forum. Let me know if I can help you in any way.

Cheers, Zak
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