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KEF NT25 SP1240 UniQ Tweeter fixing - unmounted tweeter, now what?

C

Chrisburrc

New Member
A while ago, I noticed a muffled sound from my speaker, so I decided to investigate. It seems to me that it has an issue with the higher frequencies.

Following this post, I measured the resistance of the tweeter and it gave me "off limit". So I decided to unmount it fully and see what I can do with it. Smelling the tweeter doesn't really smell like burn, but rather like the leather sofa of my grandmother who used to smoke inside... I can't tell if this is because the speaker is gone bad or the previous owner was smoking next to the speaker.

I attached 3 pictures to show where I stand. I don't know if I should try to remove the voice coil from the base. I tried but the two part do not seem to split easily.

I'm a bit stuck at this stage, I see potential directions to go:
  1. Do not further unmount, clean with isopropyl alcohol, add new ferrofluid and seal everything.
  2. Try to open the voice coil and check if something is wrong (due to the results of my resistance measure before) -> if so, how should I access the voicecoil?
I also checked on the 2nd speaker, which sounds noticeably better, the tweeter also gives me "off limit" resistance, so maybe it's an expected result?

Thanks in advance.IMG_20220122_161555.jpg IMG_20220122_161555.jpg IMG_20220122_161605.jpg IMG_20220122_161625.jpg
 
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Quick update, I could move forward with the unmounting. Now I face two issues: the ring is broken, and one of the voice coil wire is broken. At this stage, does it make sense to keep moving forward and fix it?

Or should I rather clean up everything with Isopropyl alcohol and replace the voice coil with this part?
 

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I'll keep posting update as I'm making my way through it. Hopefully it can serve someone else in the future.

So I fully removed the voice coil, it's broken, I'll have to get another one. Any suggestion? There are few options on Ebay, such as this one.

I started to remove the dried out ferrofluid using paper, as instructed in many other forums. I've ordered some Isopropyl Alcohol to clean it clearly.

I'll order the new ferrofluid, and the glue from Simplyspeakers.

Since I'm based in Europe and parts are coming from China and US, I'll probably wait a few weeks.IMG_20220123_154333.jpg IMG_20220123_154340.jpg
 
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