Dead Tweet That Uses Ferrofluid

vinylndunks

vinylndunks

suisanhayamaticrealis
Will cleaning and replacing the ferrofluid in a dead tweet get the tweeter working again or should I just source another tweet? Considering taking a crack at it if there is a chance the tweet will work again. Have a set of Kef 10's and the tweet on one of them stopped working altogether, no sound at all. Has anyone had any luck replacing the fluid in a dead tweet and getting to work again?
 
Nope. Unfortunately the ferrofluid only helps power handling by allowing the heat from the voice coil to dissipate into the magnet structure more efficiently that just air. Once the voice coil is burned, replacing the ferrofluid won't revive the tweeter.
 
Thanks for the heads up, I guess I will have to source a tweet. I may clean the other one that still works for some insurance.
 
Pull the "dead" tweeter and check it with a DMM for DCR. If it reads open or zero, it is toast. It is possible (not really likely) that the VC is "frozen" in the dried out ferro-fluid, but you can verify continuity (or lack thereof) with a quick check with a DMM. If it reads open, check all connections/leads for continuity, as well, before declaring it "dead".
 
The ferrofluid also tunes the tweeter, removing it is not a good idea. Best to buy a pair of tweeters at this point so that they are matched.
 
Well I have seen this issue on different threads with other tweets where the sound was cutting in and out, when the ferrofluid was cleaned and replaced the tweet worked again. Are you saying if it's broke don't fix it? The speaks are over 30 years old so the fluid gotta be sludgy, so a cleaning and replacement wouldn't hurt it I would imagine. Then again I'm no pro. Anybody else replace the fluid on a tweet that was working with success?

@savatage1973 thanks for the tip, I checked and it's dead.
 
vinylndunks said:
Well I have seen this issue on different threads with other tweets where the sound was cutting in and out, when the ferrofluid was cleaned and replaced the tweet worked again. Are you saying if it's broke don't fix it? The speaks are over 30 years old so the fluid gotta be sludgy, so a cleaning and replacement wouldn't hurt it I would imagine. Then again I'm no pro. Anybody else replace the fluid on a tweet that was working with success?

@savatage1973 thanks for the tip, I checked and it's dead.
Click to expand...
I've replaced the ferrrofluid in several working tweeters with no problem. It's best to to it before the tweeter stops functioning, doing it afterwards isn't going to accomplish anything.
 
vinylndunks said:
Anybody else replace the fluid on a tweet that was working with success?
Click to expand...

Yes, I have removed old ferro-fluid, cleaned everything, and put in fresh fluid with great success. The fluid is there primarily for heat dissipation to allow the tweeter to handle more power, but it also does have a certain degree of damping effect. Once it starts drying out and turning to sludge, not only does it not dissipate heat as effectively, but the level of damping increases dramatically, making the sound "dull". Fresh fluid not only increases the longevity of the tweeter, but also restores the original high frequency response of the driver.
 
If the tweeter is not working it is more likely than not a break in the VC wire somewhere or a short in the VC wire somewhere
 
If you know the impedance of the good tweeter, and the dome material, as well as size. It might be possible to find a donor to swap it over. I've done this type of repair on a number of different tweeters, including Kef NT19 coaxial tweeters. Knowing the specs of the original helps too in finding donors.
 
darkblue94 said:
I've replaced the ferrrofluid in several working tweeters with no problem. It's best to to it before the tweeter stops functioning, doing it afterwards isn't going to accomplish anything.
Click to expand...

This is what I figured, thanks. Also thanks to everyone else who provided input.
 
Good luck I hope you get the tweeter up and running! Did you end up having a burnt voice coil? I had a pair of tweeters that stopped making sound but voice coils were fine, it was the ferrofluid that had dried up and locked them up. New ferrofluid did the trick.

Here's a good youtube video on the process, there are many more if you search:

 
ra.ra said:
Can either of you recommend any good AK threads that show this process in step-by-step detail? I've got a tweeter that has mysteriously come apart and I'm a bit stumped.
Click to expand...
I found a couple of good videos on YouTube. Just key in "tweeter ferrofluid replacement."
 
Johnny_Law said:
Good luck I hope you get the tweeter up and running! Did you end up having a burnt voice coil? I had a pair of tweeters that stopped making sound but voice coils were fine, it was the ferrofluid that had dried up and locked them up. New ferrofluid did the trick.

Here's a good youtube video on the process, there are many more if you search:

Click to expand...

Yep, gonna have to get another. What is the best way? To use blotter paper or masking tape? I came across this site in my searches...

https://speakerrepairshop.nl/index....uid_in_tweeter_vervangen&lang=en#.XDo-Fml7mUl

If the blotter paper is better, any specfic size (thickness) the paper comes in? Looking at getting this below but I don't know if it's thin enough. Also, I want to know if anyone else used the masking tape method and if that is better...

https://www.ebay.com/itm/Pk-10-Rose...b:g:4SAAAOSw7z1aAfZ5:rk:3:pf:1&frcectupt=true
 
vinylndunks said:
Yep, gonna have to get another. What is the best way? To use blotter paper or masking tape?
Click to expand...

There's no harm in experimenting with things - you likely won't do any harm. I have tried a bunch of different things and personally prefer to use 3x5 index cards - they seem to be the right combination of stiffness, thickness, and absorption. Although some of it will soak up, depending on how bad the fluid has hardened, part of the exercise will be the scooping of the hardened fluid. I've used a thin piece of plastic like from a gallon of milk which I cut into a little hook to help with the scooping.
 
Johnny_Law said:
There's no harm in experimenting with things - you likely won't do any harm. I have tried a bunch of different things and personally prefer to use 3x5 index cards - they seem to be the right combination of stiffness, thickness, and absorption. Although some of it will soak up, depending on how bad the fluid has hardened, part of the exercise will be the scooping of the hardened fluid. I've used a thin piece of plastic like from a gallon of milk which I cut into a little hook to help with the scooping.
Click to expand...

Sweet! Those index cards I actually have on hand so that will save me cash. Just ordered the ferrofluid. Pricey. Wish I had a gallon of that stuff to sell on AK! Thanks Johnny.
 
Might want to confirm the tweeter is actualy dead....swap the tweeters in your soeakers, there's a small chance its a crossover or connection issue.
 
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