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T33 Ferrofluid - Anyone know?

 
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SimplySound
Junior Contributor 20+


Joined: 08 May 2012
Posts: 21
Location: Albuquerque, NM

PostPosted: Tue Mar 12, 2013 9:41 pm    Post subject: T33 Ferrofluid - Anyone know? Reply with quote

Hi Folks,

I contacted Ferrotec to inquire about what Ferrofluid was used in the T33's. Especially the T33 SP1210 used on the KEF R107. I am considering having the fluid replaced and it would be good to know what type and how much was used in the original specifications.

Does anyone here (Colin and Company) know what type of fluid was used on the T33's? A specification or any information?

They don't have any documentation of what was used at Ferrotec, but they might be able to get close with some additional information on the speaker design. Here is a link to what they need filled out.

Can anyone fill in these blanks?

Here is their response;

Hi Doug,

I have been doing some digging, and it seems that KEF was purchased by Gold Peak (GP) Industries. GP is a Hong Kong based company. They acquired several brands over the years…including Celestion. Unfortunately, I am not sure that there is anyone around who would remember which ferrofluid was used in speakers built 25+ years ago.

I do have a couple of avenues to explore, but what might help is if you can scare up any of the specs on these speakers then I can see which fluid seems like a good fit, including the fill volume.

I am attaching a document to this email message that is called the “Loudspeaker Information Sheet”. If you can fill out any of the information fields included, it would go a long way towards helping me determine a good fluid fit.

If you can’t give me much information that’s OK, we can go with one of the default fluids that we currently use for general purpose. It may not be quite as perfect as the original, but it will be close. In the meantime, I will continue to dig.

Thank you and best regards,

Vanessa M. Rene

Product Specialist - Ferrofluids
Ferrotec (USA) Corp.
33 Constitution Dr.
Bedford, NH 03110
Tel: (603) 472-6455
Fax: (603) 472-6449
www.ferrotec.com

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Kef 107's-"One of the few full-range loudspeakers that I have experienced to touch the soul—not just of the music, but of the listener."—John Atkinson
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SimplySound
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Joined: 08 May 2012
Posts: 21
Location: Albuquerque, NM

PostPosted: Tue Mar 12, 2013 10:55 pm    Post subject: Reply with quote

Ok... dug around on the site and found this from Speaker Guru....

speakerguru wrote:
More info here http://ferrofluid.ferrotec.com/products/ferrofluid/audio/
KEF used to use the now obsolete APG512 which you won't find on this site. From memory it was a 75cp fluid. i.e. the fluid was used primarily to increase conduction of heat to the metalwork, not to provide damping. The base fluid is a synthetic oil and I guess everything dries/evaporates eventually...


Also....

speakerguru wrote:
APG S15N looks to be close to the original in viscosity. If Ferrotec are cautiously recommending it, then it is probably the most suitable for T33 use. The exposed part of the T33 vc is high temperature cured epoxy, aluminium and CA (superglue) adhesive. Not much risk of a bad reaction with an oil based fluid, I think, but no guarantees.


So I will see what Ferrotec has to say about APG512 and using S15N as a replacement!
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Kef 107's-"One of the few full-range loudspeakers that I have experienced to touch the soul—not just of the music, but of the listener."—John Atkinson
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speakerguru
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PostPosted: Tue Mar 12, 2013 11:13 pm    Post subject: Reply with quote

You beat me to it Laughing
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SimplySound
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Joined: 08 May 2012
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Location: Albuquerque, NM

PostPosted: Wed Mar 13, 2013 6:26 am    Post subject: Reply with quote

speakerguru wrote:
You beat me to it Laughing


All I can say Guru, is a big thanks so much for the support you guys with "knowledge" provide to the KEF Fans in the UK and a broad... without you guys we'd be lost!
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fan4fan1
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Joined: 21 Sep 2004
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Location: South Pittsburg, TN

PostPosted: Fri May 24, 2013 5:28 am    Post subject: Reply with quote

http://app.audiogon.com/listings/speakers-kef-t33-103-105-107-series-repair-service-for-dried-out-ferrofluid-2013-05-20-vintage-equipment-23229

This ad has been showing up on Audiogon here in the states for a while now. The poster has a nice passive preamp business going, and I've e-mailed him a couple of times. I think he's worth a shot, though I have no idea if the type of ferrofluid he's using is exactly what is needed. Be worth getting in contact with him though. $50 a piece is reasonable in my opinion and I'm considering sending my old pair in (using the Morel's now with very nice results so no hurry).

John
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ZeroG
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Joined: 18 Aug 2013
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Location: Southern California

PostPosted: Tue Aug 20, 2013 3:24 pm    Post subject: Ferrofluid replacement Kef T33 Reply with quote

Hi, I'm new here, and quite enamored of my Kef 104/2 and in process of restoration.

It's really not that difficult to replace the ferro fluid. I also contacted Ferrotec first, which ultimately steered me back to Parts Express for the ff. It comes in a kit with a pre-measured amount of ff, some filter paper strips and a small booklet of instructions.

After carefully removing the tweeters, you can gently remove the diaphragm by inserting a razor blade under the rim and cutting under the adhesive tape. Be careful not to insert it too far or you may cut the tweeter former or VC. Gently cut through the double-faced tape and try to save as much as possible, twisting the blade in a few areas to raise the diaphragm. Remove the diaphragm (mark one side first) and examine for damage. Hopefully all you'll see is a little gunk.

I took a 10 mm strip of plastic shim stock (for VC) and wiped out the gunk with it. Then I took a coffee filter and cut a strip to wrap around the shim stock and kept wiping the gunk out. Finally I finished with the supplied cleaning strips (thicker than the coffee filter so use by themselves) and wiped until they came out clean.

Clean the inside and outside of the voice coil very gently. I used a tiny bit of WD-40 on a q-tip and a makeup sponge and wiped ever so gently. Let all the WD-40 (or isopropyl) evaporate. Cut the tip of the ff vial, insert it, and just squeeze it in. It's self leveling, so no worries about spreading it around.

Reassemble and that's that. I previously did this same repair on a pair of ADS L300s. It's very much like refoaming a woofer. Once you've done a couple of them you're an expert.

Both tweeters were functioning prior to the ff replacement and seemed in very similar (good) condition. Following the ff replacement they are both performing much better, though one seems very slightly less bright than the other, and I would presume that to be related to either crossover age or room acoustics . I'll get around to swapping out the top end modules to verify that.

Hope this helps. (I'd post a picture if I knew how. Can they simply be attached?)
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speakerguru
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PostPosted: Tue Aug 20, 2013 8:49 pm    Post subject: Re: Ferrofluid replacement Kef T33 Reply with quote

ZeroG wrote:
(I'd post a picture if I knew how. Can they simply be attached?)

I think you have to post a link to a picture hosting site of your choice.
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MartinW
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PostPosted: Sun Feb 23, 2014 2:19 pm    Post subject: Reply with quote

Thread revival time!

I finally got around to renewing the T33 ferrofluid on my 104/2s after refoaming the B200s some time ago (background and a picture-heavy refoam guide here if you're interested http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=1472).

The only easy source for the ferrofluid that I found was Parts Express which had AGPL11; this is more viscous than the 75cP mentioned above but much better than the 1994 gunge it replaced.

It was pretty easy to do, as described by ZeroG. It took about an hour or so to remove them, clean them up, add the new fluid and refit. I've previously felt that the treble on my 104/2s could be a little strident - it's possibly imagination and wishful thinking but it seems to have tamed it somewhat.
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keffan
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Joined: 19 Feb 2011
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Location: USA

PostPosted: Sun Jun 12, 2016 2:15 am    Post subject: T33 Ferrofluid Replacement Reply with quote

My 104/2 still works and sounds good too. However, I do want to replace the ferrofluid of the tweeters before they are burned in high heat. Do I need to replace the adhesive tape when reassembling the diaphragm? How do I make sure that the VC could be insert back correctly?

Thanks

Kwok
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speakerguru
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PostPosted: Sun Jun 12, 2016 10:14 pm    Post subject: Reply with quote

If you are super careful, you may be able to remove the diaphragm assembly without damaging the tape. Otherwise you need to source a thin double sided adhesive tape.

The diaphragm assembly is located on the magnet top plate by holes in the pcb ring and semi-shear pins in the top plate; very easy.
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keffan
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PostPosted: Mon Jun 13, 2016 5:04 am    Post subject: Reply with quote

Thank you very much for your reply. My concern is whether the vc needs to be exactly in the middle inside the gap? What is the pcb ring?

Thanks

Kwok
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speakerguru
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PostPosted: Thu Jun 16, 2016 1:09 pm    Post subject: Reply with quote

keffan wrote:
My concern is whether the vc needs to be exactly in the middle inside the gap? What is the pcb ring?

Everything if fixed to the pcb ring and the ring is centered with respect to the magnet gap by the pins. Nothing can move off-centre.
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SaSi
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PostPosted: Fri Jun 17, 2016 9:30 pm    Post subject: Reply with quote

How does a tweeter with dried up ferrofluid sound? Does it sound bright or dull?

My KEF 107/1 tweeters appear to sound a bit bright. I am not sure if the first series had ferrofluid or not. Wonder if it's a matter of that or capacitors running away from nominal values.
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TSWisla
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PostPosted: Wed Oct 19, 2016 6:38 pm    Post subject: Reply with quote

I can't seem to find a consensus regarding the ferro fluid for 104/2 tweeters. Is the parts express fluid adequate or should I be using fluid from somewhere else? Thank you.
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speakerguru
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PostPosted: Thu Oct 20, 2016 8:55 am    Post subject: Reply with quote

Please read the sticky: http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=1695

When I did this job on my 102 speakers I could not say I heard any difference before and after. I'm certain I could have measured something but I guess that my aged hearing is to blame.
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