SpeakerTalk

golanr · Posted: Fri Feb 10, 2012 5:46 pm Post subject: KEF T33 SP1192 Ferrofluid

Hi,
The ferrofluid in my T33 has completly dried out, I have remove the voice coil and cleand the gunk around it and inside the magnet cavity.

Now I am ready to apply the new ferrofluid but don't know how much to add.

Any recomendations?

Thank you,

speakerguru · Posted: Fri Feb 10, 2012 7:03 pm Post subject:

100 micro litres. It barely fills up all the way round but is enough when the coil goes in and displaces some.

ColinR · Posted: Fri Feb 10, 2012 7:09 pm Post subject:

golanr · Posted: Fri Feb 10, 2012 11:08 pm Post subject:

Thank you guys. I'll report the difference once I am done.

proffski · Posted: Sat Feb 11, 2012 12:15 pm Post subject:

Does the Ferrofluid dry out over time because of the heat generated within the motor assembly or does it contain volatile constituents which would evaporate over timeanyway if just left and not used?

Or both? Confused

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golanr · Posted: Sat Feb 11, 2012 4:49 pm Post subject:

I believe that the answer is both. The fabric used in the T33 dome is not completely sealed and in time allows the FF liquid part to escape leaving behind only the solid material.

ColinR · Posted: Sat Feb 11, 2012 5:01 pm Post subject:

Been digging Wink

.

According to KEF ferrofluid in drive units has a life expectancy of 20-25 years.

So "party-time" and otherwise over cooking speakers with central heating/South facing windows will reduce their lifespan, I don't think moving into a freezer will help Laughing

.
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proffski · Posted: Sat Feb 11, 2012 8:01 pm Post subject: KEF 104/2 Special

Cheers guys, I see that my 104/2s which are still in the family are yet to show any foam rot and the treble is sweet and beguiling. Have we been lucky or what?
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

speakerguru · Posted: Sun Feb 12, 2012 12:04 pm Post subject:

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.

I have my head firmly in the sand re my 102s. If they sound alright and I don't look, the ferrofluid must be OK Wink

.

proffski · Posted: Sun Feb 12, 2012 12:11 pm Post subject:

fan4fan1 · Posted: Thu Apr 19, 2012 7:59 pm Post subject: Ferrofluid Replacement

Hey Golanr, I wondered how your ferrofluid replacement went. I have a pair of 104/2's bought new in '86. The tweets still sound like they always have to me (a little on the dark side, but my ears are getting old!).

My understanding is the fluid dries out over time, just from the air. I've seen a pair of Morel replacement tweets on e-bay for these speakers but they're kinda' pricey (over $200 USD). Also looking into SP 1353's which I think are still available and I've seen quite a few reviews that they are a good drop in replacement.

Very keen to hear what you think after your overhaul. I'm having the B200 woofers re-donutted and this is a good time to look into this I think. Thanks in advance...

John in Tennessee
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golanr · Posted: Sun Apr 22, 2012 10:19 pm Post subject:

Well, it was pretty strait forward. Removed the four screws and the square plastic cover came off, then the dome will come out with the coil, do it slowly as it could stick to the magnet. I then used 90% alcohol to clean the voice coil and the cavity where it fits. Then put 3 drops of the FF and assembled everything back. HIgh Frequencies are more pronounced, and easier on the ear, hard to describe but it is like the Lund is less brittle.

I hope that helps.

iso · Posted: Mon Apr 23, 2012 8:35 am Post subject: ferrofluid

Spekerguru said that now obsolote APG512 was used as OEM. Which type matched best in your(or Spekergurus?) opinion to APG512 properties and where did you buy it.

How old were your T33:s and how big improvement this rebuild offered.

Best Regards

speakerguru · Posted: Tue Apr 24, 2012 10:17 am Post subject:

Try to get a low viscosity type, around 75cp, in order to minimise any change to the response around the tweeter resonance.

It could be difficult. I had a quick look on ebay and no one seems to include any technical data in their listings.

iso · Posted: Tue Apr 24, 2012 11:42 am Post subject: ferrotec.com

Ferrotec.com seems to list several types of ferrofluids + refill kits. I haven´t asked yet about their distributors. They inform that also adhesives and other materials used must be considered when choosing right fluid. There seems to be lot to be considered...

Did all 4 ohm T33 variants SP1191, SP1210 and SP1265 use ferrofluid and is it possible to use their cone assemblies as replacement to other types.Ie. use SP1210 plastic front plate and magnet assembly with SP1191 or SP1265 cone assembly.

Best Regards