FerroFluid aging

I know the topic has been discussed previously but this one is a tad more specific.

Did B&W use ferrofluid in the 800 matrix (801 - 805's) series (1-3) tweeters?

If they did, is there any known issues with the drying out of the ferrofluid in the 800 series specifically?  Yes I had some Vifa tweets that it happened to, but sadly my 805's died from other causes so I don't know if they would have lasted.

Any info would be appreciated.


https://www.stereophile.com/content/bampw-matrix-800-loudspeaker-specifications  Ferrofluids dry up after about a decade or so and can be replaced but it's a pain. And once dried up you have metal in your VC thus damage can occur. I avoid it at all costs its a cludge to make cheap overworked tweeters last a bit longer. 

Thank you for the link, however, that is the one tweeter in the 800 range that is not the same.

Even the link to the 801 s2  doesn't specify FerroFluid or not.  But after seeing it in the 1,25" tweeter I would "assume" it is in the 1" also.




It's easy to tell if you disassemble the tweeter.  The coil will be crusted over with it and need to be cleaned.

It’s easy enough to replace FF if you can open the tweeters up. Did it with my Seas H400 tweeters a couple of years ago, and was surprised that it made an audible improvement once replaced.

Once the voice coil is separated from the magnet, take a piece of index card or folded paper and scrape out the residue from the magnet gap. Refill it with fresh ferrofluid about 3/4 up. It’s useful to have a syringe or squeeze bottle with a fine fill tube for injecting it into the gap. It’s not rocket science, and there are plenty of pics and vids on Google.