NOS Audax TM025F7 Ferrofluid leak?

[MuseChaser]

Just finishing up the cabinets to the rear surrounds in the D'Appolito/Audax home theater system design and noticed that one of the two tweeters I bought new years ago (but never used) shows visual signs of possible ferrofluid leakage, but I'm just guessing; the white round label on the back of the driver is stained sort of a light oily brown over most of it's surface.

If it IS a ferrofluid leak, can it be fixed? PartsExpress and SimplySpeakers both sell ferrofluid replacement kits, but I can't ascertain as to whether or not this specific driver is serviceable.

TIA...

 

[Mark Tillotson]

Definitely ferrofluid, there's only one sort of fluid in a tweeter!


I suspect it has separated somewhat, and the magnetic gap is now loaded with thicker stiffer fluid due to the seepage. I guess you can run them both and compare them side by side with a measurement mike or equivalent to see if they work the same (a good sign), and this ought to mix up the fluid again (wear ear protection and use highish volumes at their lowest frequency). Only a guess mind you.

 

[MuseChaser]

Definitely ferrofluid, there's only one sort of fluid in a tweeter!


I suspect it has separated somewhat, and the magnetic gap is now loaded with thicker stiffer fluid due to the seepage. I guess you can run them both and compare them side by side with a measurement mike or equivalent to see if they work the same (a good sign), and this ought to mix up the fluid again (wear ear protection and use highish volumes at their lowest frequency). Only a guess mind you.

Thanks, Mark. I've attached a pic of the driver, just for yucks. I've looked at it closely, and I don't see any way to either disassemble it or a visible crack in which to insert thin blotting paper and then refill w/ ferrofluid. Also can't find any similar drivers currently manufactured and/or easy to get in the US. Peerless/Vifa make one that looks, spec- and measurement-wise, it would be a good replacement, but the 8 ohm version seems to be relegated to European sources, for whatever reasons. Here's hoping my Audax isn't past salvation.. perhaps the stain I'm worried about is just... well... a stain?

 

[Mark Tillotson]

Are you setup to do some sort of comparative measurement between the two tweeters? If they test alike for impulse response, or distortion, especially at high volume, that's a sign the cones are behaving the same - although they might both have dried up a bit.