Ferrofluid questions.

I am considering changing out the ferrofluid in the tweeters on my Thiel CS 3.6 speakers. It appears that I should be able to do the work myself. Someone gave a link in another thread to little tubes of the ferrofluid that you can buy for less than $10 from Parts Express.

I have been attributing unclear vocals to my Bryston 4Bsst2 amp being not clear enough. I may still upgrade the Bryston amp to the "cubed" version of the 4B but I’m starting to wonder is it more an issue of my older Thiel speakers’ tweeters having overly resinous ferrofluid.

Could too old of ferrofluid in a tweeter contribute to coarseness in the treble range? What about a slight lack of vocal elocution? I have resorted to using the Soundhound app on my iPhone when listening to vocal music in order to bring up the lyrics. Or, I read the lyrics on the CD cover if they are provided.

If the new ferrofluid improved vocal clarity I would be a very happy guy.

I hope I don’t damage the tweeters in the process.

Also, if you can change the ferrofluid on the tweeter, does the midrange cone work in the same manner?

I look forward to optimizing my speakers further. Thanks for any help you can give.

I'm not an expertin Thiel, but yes, old ferrofluid tends to gunk up the coil.

AFAIK, this was really only a thing in tweeters, so no, you won't have the same issues in the mid.

Definitely worth doing first given the age of your speakers.
To be clear, you need to be prepared to clean the VC as well as replace the fluid. :)

thank you @erik_squires . What does VC stand for?

The fasteners for the tweeter are exposed right in front of the speaker and then there is a triangular plastic guard covering the dome tweeter with more accessible fasteners.

I saw a few you tube videos where they show how to wick out the old fluid. One video demonstrated using a piece of masking tape, folded in a way that the adhesive was on both sides of the outside in order to remove the old ferro fluid. The other video I watched, they just used like coffee filter paper one little piece at a time until there were minimal dark stains on the paper. Then they took more of the coffee filter paper with some rubbing alcohol (or pure grain alcohol?) on it in order to get it even cleaner before they put the fresh ferro fluid in.

VC = Voice coil

The alcohol part of this is wahat I referred to. :)  Definitely want to leave it squeaky clean if you are going to to the work.  No sense in filling it with fluid, finding out you still have issues, and then cleaning it the second time. :)

Readers in DIYAudio however are going to have a lot more first hand experience, I recommend looking at old threads there, and asking questions.



I am not very handy, and likely looked at the same you tube videos you did.

In fact, I took my tweeters apart, cleaned them and reapplied the ferrofluid in my scanspeak tweeters. My tweeters were so much easier to disassemble than those in the you tube videos. If they had been any harder I would not have attempted it, you can mess up.

So this is what I am getting at, your Thiel’s may be really easy or difficult to work on, hopefully you can find some precise information for your specific tweeter before attempting.

On the other hand, if it was me, and I wasn’t totally comfortable, I would call Bill at Millersound and inquire if he would take it on. He is great to work with and reasonable as all get out.
Good luck
lots of Thiel owners including two guys whp worker there and one that services Thiel over on the Thiel thread - curated by Jafant. The 3.6 is a wonderful speaker when functioning as designed. The triangle shaped bit is a phase plug. Also, there are Ferrofluid midranges they tend to be domes, but.. i would do a bit of searching.

Coherent Source Service , Rob can help you.
One day I'll have to replace ferrofluid as well.  Not only in tweeters but also in 6" midrange that uses it for suspension (no spiderweb suspension).   I know it can be obtained from Parts Express or Madison Speaker Store, but wonder if there is only one type/quality of ferrofluid.  Do they make it in different quality or viscosity?
Yes, there are differences in ferrofluid types and brands:


One of the little known facts about Paradigm Loudspeakers, we still buy ferrofluid for our Tweeters, Mid-Ranges, and Woofers from the original manufacturer of it - not from a knockoff company.

Just curious: How much are new tweeters? Can't be more than $100 each unless out-of-production. How about an upgrade? these speakers must be 20 something years old -must be better tweeters out there. Finally, feasible to use an ultrasonic cleaner to remove goop build up (in the originals)? 
I suspect these tweeters are out of production. If you could purchase replacement tweeters of the exact spec they would surely be more than $100! These speakers are at least 30 years old. The sound is still quite good. I’m just wanting to perfect it a bit more.
Thank you @tomic601 I will contact Rob at Coherent Source Audio with the question of ferroflid replacement. 
Just curious: How much are new tweeters? Can't be more than $100 each unless out-of-production.
Original will be more than that, if still made, also never sub them, as the speaker resale will fall off a cliff. 

It'll be $100 for new diaphragms/voice coils if you can get them, and you still have to clean out the old Ferro Fluid from the magnet gap.
So you  may as well just clean the old diaphragm coils as well as save that $100.

Cheers George
Hi OP, I thought you might want to check out our range of Ferrofluid products https://frenergy.com.au/collections/magnetic-ferrofluid. If you have any questions you can check out our product page, the Knowledge page or get in contact with us, we'd be happy to help.
They were made by Vifa and are a metal dome so you have to be very careful not to dent the dome. I would tape something like a tuna fish can over it for safety. Rinse the gap out with electronics parts cleaner like this 
Until it comes out clear. I'm not sure what kind of seal is in there, probably an "O" ring which you might want to replace. Home Depot has a selection of sizes.
One of the best speakers made in it's day considering the price. Good Luck!
I personally am against ferrofluid now. When the ferrofluid tweeters first came out, I thought it was great and a breakthrough, mainly for the added power handling. After listening to FF tweeters compared to non-FF tweeters, I can say the fluid does affect the sound negatively. Maybe like some have mentioned, various quality and they do tend to thicken over time. I'm now a big fan of ribbons and JBL 2405 type diaphragm tweeters. It would be interesting to hear the tweeters if you decide to clean them out to remove the ferrofluid, before adding new fluid. Maybe reassemble without the fluid and listen at lower volume. I would be very interested in this test should you decide to pursue...