Tannoy 'Oxford' T125 HF Driver - Ferrofluid replacement

[Kanders1]

Has anyone ever changed the "Ferro fluid" in theses units..? (Driver model No. 1108B)

I have been in touch with Tannoy and the answer I received was they are not serviceable... helpful.

I have seen the fluid available.. just wondered if its all the same viscosity etc...? some places state they are selling Tannoy fluid..?

any help greatly appreciated..

Cheers

[spendorman]

I think I had these apart years ago, one of mine stopped working. Don't remember seeing ferrofluid in there. Tweeter coil was open circuit though. Audax made unit I believe. Bought two second hand ones on ebay, both no good.

[Kanders1]

Cheers..

One of mine was not working.. when I checked the coil no reading at all so took it apart and there is fluid inside... brown and crusty... I have a new 'used' one coming. Just wondered if anyone had done this job...?

[spendorman]

Perhaps the brown and crusty was burnt out coil not ferrofluid. I was thinking of fitting a different tweeter to the horn, looks possible.

[Kanders1]

Nope... defo fluid I poured it out... the original spec quotes the use of the fluid...

http://www.hnny.nl/archief_tannoy/pdf-brochures/tannoy_stratford-oxford-cambridge.pdf

[struth]

Parts express and simply speakers do kits i think.. Dunno about oxfords though.

There was a guy on emotiva lounge did a walk through for doing tweeters, that might help

http://emotivalounge.proboards.com/thread/34281/fixing-ferrofluid-tweeters

[spendorman]

Nope... defo fluid I poured it out... the original spec quotes the use of the fluid...

http://www.hnny.nl/archief_tannoy/pdf-brochures/tannoy_stratford-oxford-cambridge.pdf

Ah, OK then. I think that the crossover uses electrolytic capacitors in it. I would replace these as they are likely to off by now, could be one of the reason the tweeter failed.

[Kanders1]

I swapped the good tweeter over to check... all good there. But yes that's on the list.. cheers

[Kanders1]

Ah, OK then. I think that the crossover uses electrolytic capacitors in it. I would replace these as they are likely to off by now, could be one of the reason the tweeter failed.

If the cap in that speaker is failing would the good tweeter still work..? or are you saying that its a cause and over time will make a replacement unit fail..?

Cheers

[spendorman]

Quite possible that the new tweeter will work, but the old capacitor(s) could kill the new good unit.

Happens quite a lot in old KEF speakers. T27's blown by bad electrolytic capacitors. They can increase in capacitance, lowering the crossover frequency, putting more power through the tweeter than designed.

[walpurgis]

Ferrofluid is the bane of older 'modern' speakers and it will continue to be a problem. I avoid speakers and drive units that use it.

[spendorman]

Ferrofluid is the bane of older 'modern' speakers and it will continue to be a problem. I avoid speakers and drive units that use it.

I bought some B&W DM22's, one of the tweeters had low output. took it apart and removed the dried out ferrofluid, seemed OK after that, did the same to it's brother, just to match.

[Kanders1]

yep understand...thanks, there is only one cap on the crossover... heavily glued in place with the value on the bottom...:( ill check the other side see if its up the other way... but I'm sure someone will have posted the value anyway.

[Kanders1]

Ferrofluid is the bane of older 'modern' speakers and it will continue to be a problem. I avoid speakers and drive units that use it.

This may be true... but I have a good sound and with some TLC the ferrofluid can be changed and the speakers can live for another 10 years +.... :)

[danilo]

Years ago when ferrofliud divers were first starting to time out.
Many advocated removing All traces of the stuff and running without it.
Some claims of improvements ensued.
No idea if accurate... But?

[walpurgis]

Ferrofluid provides heat dissipation, thereby raising the power handling of the driver. It also gives some damping to the coil and diaphragm movement, so removing it will give unpredictable results.

[Kanders1]

Found a supplier of the ferrofluid. And will clean the coils and replace the fluid.
Thanks for the input and advice.

Cheers :)

[Geoff101]

(Shameless advert below)

If that doesn't work, I think the Stratfords I have for sale use the same tweeter (you'd need to check but they look the same). Both are working.
http://theartofsound.net/forum/showthread.php?44606-FS-Tannoy-Stratford-Speakers

[Kanders1]

Thanks, good value for those the tweeters are going for £30 each on Ebay...!

Both of mine are working... going to change the ferrofluid as a "preventive maintenance" job

Karl

[Kanders1]

So quick update in case anyone else wants replace the ferrofluid is in these.
It's quite simple to do.

Read through first.. Take pictures if you can in case you forget what goes where ��
I got the ferrofluid from eBay Sonitus audio ferrofluid by just_add_music

Remove the tweeter...!

1. Remove the black plastic ring on the front of the tweeter, I used a Stanley knife blade to lift it and slipped under, the glue is old and gives up quite easily. Try to avoid cutting fingers as blood does not mix well with ferrofluid ��
2. Undo the tree screws holding the horn casting, left of carefully as it seals against the coil and dome. Note how tight they are.
3. Loosen the screw that holds the coil and dome connectors don't remove it yet.
4. Use something thin and made of plastic to lift the voice coil and dome seal, I used a plastic toothpick the point removed it's enough to lift the seal without damaging the coil. once the seal is free remove the screw and VERY CAREFULLY lift the coil and connector plate out set aside.
5. Look out for a paper gasket and remove.
6. Clean out the magnet slot. I used WD40 and contact cleaner with thin plastic to remove crusty deposits...make sure the groove is clean and no dust or cleaning cloth paper or whatever you use is left in there.
7. The coil, be careful the wires are thin and old...! I only needed to clean the inside which is the paper spool I used Cotten bud with WD40 and it seems to clean of the old ferrofluid easily. Be sparing with fluid on the spool. Don't touch the coils unless you have to. If you do need to clean them be very very gentle...! Clean the seal and paper gasket.
8. Once it's all clean and dry the fun starts ferrofluid! I bought two .5 ml syringes you will only need one.. So if you have never used this stuff befor it lives up to its name... Ferrofluid is liquid that's got iron in it and guess what it just loves a big fat magnet..! So use the tiny nozzle that comes with it and take it slow the magnet will pull the fluid from the syringe! You may need the slightest pressure but it won't take much. I filled mine to just below the top. There is a huge cavity behind the face so I don't think any pressure will result if you over do it a tiny bit. You can use the syringe to remove but the magnet really does not want to let go and you can end up with even more fluid in..!
9. Once you have conquered the ferrofluid then replace the seal and coil, it fits nicely into the casting ring press evenly all round use the plastic tool/toothpick. Check the alignment of the connection plate before you press the coil home.
10. Replace the screw for the connection plate don't over tighten. Hold the plate as you tighten the screw in case it tries to turn as you tighten it. There is a locating pin but it's a loose fit.
11. Put the casting back on, make sure its clean on the face that seals the coil and that it sits squarely. Replace the screws and tighten them a little at a time try to keep the pressure equal. Mine were quite tight so take note as you undo them to get an idea of how much they need. ( I'm sure someone will know the correct torque for them...lol)
12. Connect and test, if all okay then replace the plastic ring. Mine still had enough residue stickiness to hold firm but a sliver of thin double sided tape should do the trick.
If it's not okay...🤔 Then you may have broken connection wire. Check solder back on remember the wire has a lacquer coating and will need to be removed first.

Hope this helps.. It does make a difference to the sound. The tweeter was very hard and loud before, after replacing the ferrofluid in one I compared them and the sound was definitely more controlled.
This worked for mine if you find something different let me know...
Cheers