AR Midrange Ferrofluid

[turnitup]

Here goes... Ferrofluid. A controversial topic I know, at least in regards to restoration. I have 2 AR12 midrange drivers, both require new surrounds. 1 is flexible in its fluidity of upward and downward motion (I.e. seemingly normal), the other is “thick” in its motion, slow motion, feeling like it is sitting in thick fluid - slow motion in its rebound. As I understand it, the mids contain ferrofluid.

I’ve read a multitude of articles on ferrofluids. While the suspension fluid can obviously dissipate over time ( based on oils, or other suspension liquids), the actual “ferro components” of the ferrofluid will not evaporate. Iron does not evaporate...

Can the suspension fluid be rejuvenated, by a solvent of sorts? Would seem logical, am I right? Since speakers are mostly held at right angles, what holds the fluid in the drivers, and keeps it from pooling at the bottom of the drivers, or eventually leaking out via natural gravity over time?

Any experience out there or thoughts? How are ferrofluids removed/replaced?

 

[SaturationPt]

You want the two midranges to match, exactly.

To that end I don’t think you can fix one, my suggestion is to remove fluid from both, clean the gaps, replace with new fluid exactly the same amount in each,

 

[GD70]

There's videos on YouTube.
This is for KEF tweeters, but the process should be the same for the AR tweeters.
You'll need to determine the VC diameter for the amount you'll need for each tweeter.

 

[turnitup]

Hi Glenn, Thanks for the reference to the video on replacing ferrofluid in a tweeter. My tweeters “seem” to be in good working order, it’s a midrange that I’m having an issue with. I’m not sure it is possible to replace the ferrofluid in a midrange without completely reconing the speaker due to the spider, etc. Have you ever run across any methods for doing this on a compression driver, such as a midrange?

 

[GD70]

Hi Glenn, Thanks for the reference to the video on replacing ferrofluid in a tweeter. My tweeters “seem” to be in good working order, it’s a midrange that I’m having an issue with. I’m not sure it is possible to replace the ferrofluid in a midrange without completely reconing the speaker due to the spider, etc. Have you ever run across any methods for doing this on a compression driver, such as a midrange?

Luckily I haven't dealt with mids. LOL! The 12's mids are unique.
Have you checked on the classic speaker pages site?

Look here, post #12.
https://audiokarma.org/forums/index.php?threads/opinions-on-ar-12-speakers.275171/

He doesn't describe how to actually replace the fluid though.

 

[drterry]

I also have two AR 12 Mid range that need to be refurbished. I had Larry do the tweeters and woofers but he did not want to mess with the mids. I don't blame him. I have not got a clue where to start! The photos show my two mids. The right one is ok (probably needs the oil changed or whatever it is you do to them). The one on the left is more suspect.

Any help would be appreciated!

 

[drterry]

You want the two midranges to match, exactly.

To that end I don’t think you can fix one, my suggestion is to remove fluid from both, clean the gaps, replace with new fluid exactly the same amount in each,

How does one go about this replacement of fluid and cleaning of the gaps?

 

[GD70]

How does one go about this replacement of fluid and cleaning of the gaps?

See the video link above, same basic process. When pulling the cones and VC rings, remove very slowly. Yes rubbing alcohol to thin the ferrofluid to aid removal.

 

[drterry]

See the video link above, same basic process. When pulling the cones and VC rings, remove very slowly. Yes rubbing alcohol to thin the ferrofluid to aid removal.

Thank you Glenn

 

[drterry]

Thank you Glenn

Do you have any suggestions about the cones etc on mine? I assume I need to remove both to remove the old ferrofluid and clean everything. One of the mids looks much worse than the other and I am guessing there may need to be replacement of material etc. Is that indeed doable? As you might guess, I have never tried this!

 

[drterry]

See the video link above, same basic process. When pulling the cones and VC rings, remove very slowly. Yes rubbing alcohol to thin the ferrofluid to aid removal.

Can the cones be replaced? And what about the surrounds? They look terribly deteriorated.

 

[GD70]

Here's my resto thread. Tons of pics and info. Should be able to answer most of your questions.
Cheers, Glenn

AR-12 Restoration & Pics

I got these for free from the same owner that netted me the ADS 910's, Magnepan SMGs (not working, but physically mint), a Luxman receiver and Mac amp. The Mac & Luxman are sold, I kept the speakers. I originally passed on the AR's, and after doing some reading about these, I realized they are...

audiokarma.org

 

[GD70]

Can the cones be replaced? And what about the surrounds? They look terribly deteriorated.

Cones, no, surrounds, yes.

 

[drterry]

Cones, no, surrounds, yes.

So, how do you separate the cones from the surrounds without damage? Forgive me, I have never done this and I promise, I wont do it again at my age! This will be my last pair of speakers and I can't wait to hear them!

 

[GD70]

So, how do you separate the cones from the surrounds without damage? Forgive me, I have never done this and I promise, I wont do it again at my age! This will be my last pair of speakers and I can't wait to hear them!

The one with the crumbling surround, use your fingers and remove as much as possible. Nextn gently pinch the cone edges and carefully run your fingers along the edges to rub it off. Don’t worry too much about remaining glue, but remove as much as possible, and get the surface a smooth as possible. If the cone moves fairly freely, I’d leave it and glue the new surround to the cone first, then the basket. There’s pics in my resto thread showing this.

Cheers, Glenn

 

[drterry]

The one with the crumbling surround, use your fingers and remove as much as possible. Nextn gently pinch the cone edges and carefully run your fingers along the edges to rub it off. Don’t worry too much about remaining glue, but remove as much as possible, and get the surface a smooth as possible. If the cone moves fairly freely, I’d leave it and glue the new surround to the cone first, then the basket. There’s pics in my resto thread showing this.

Cheers, Glenn

You are awesome! Thank you so much for helping an old guy!