Let's Talk About Ferrofluid

Nightfall

Specifically, what exactly happens when it "dries up", evaporates, or whatever it does. Does this affect the actual sound of the tweeter in question or just the power handling? Why aren't tweeters sealed so that the Ferrofluid doesn't escape? ...or are some of them? Can Ferrofluid be replaced? Any other thoughts?

Edit: I'm directly referring to the original Peerless tweeters, if that makes a difference. I'd assume the conversation would be the same no matter which tweeter we're talking about though.

honestaquarian

My understanding is that Ferrofluid is magnetic,low viscosity fluid that doesn't evaporate.Maybe asking Polk would be better.

Nightfall

@KennethSwauger Do you have an understanding of this subject?

[Deleted User]

I believe what happens is the surfactant coating of the microscopic particles eventually breaks down and the particles start clumping together, resulting in a change in the viscosity and a reduction in the damping action of the fluid. From what I gather heat is a significant cause of the surfactant breaking down over time.

honestaquarian

So it's kind of like what happens to motor oil over time.

Nightfall

Has anyone tried taking apart a Peerless tweeter and cleaning and replacing the fluid?

I have one pair from a real beat up pair of RTA-12's I found on Craigslist. 2 of the midwoofers were frozen and the cabs looked like they'd been thrown down a flight of stairs followed by being used at a frat party. I suspect the tweeters were abused, they might make good subjects for me to experiment on. Any thoughts on using Parts Express ferrofluid vs whatever the original fluid was vs cleaning and leaving no fluid?

F1nut

It turns to a sludge after some years. I haven't worked on a Peerless, but you'll want to remove the dome to gain access to where the ferrofluid should be, which is the outer edges. Clean out whatever is left, then add a small amount of new. As far as I know ferrofluid is all the same.

seabeerob213

F1nut wrote: »

It turns to a sludge after some years. I haven't worked on a Peerless, but you'll want to remove the dome to gain access to where the ferrofluid should be, which is the outer edges. Clean out whatever is left, then add a small amount of new. As far as I know ferrofluid is all the same.

Is anything in this really, the same? Pretty blanket statement

F1nut

What's your question, Rob?

seabeerob213

Saying that it's all the same sounds kind of similar to the people who say that all speaker wire performs the same, or all motor oil is the same. Not trying to say you're wrong, or right, just that with all the subtle and dramatic differences in audio, I have a hard time wrapping my head around anything being the same, unless it is in fact, the same thing, such as 2 speakers, that rolled off production sequentially.

F1nut

I did qualify my comment with, As far as I know.....

westmassguy

There are different viscosities. Which one Peerless used is anyone's guess.
https://ferrofluid.ferrotec.com/products/ferrofluid/audio/audioSelect

littlewoodboats

I have heard of ferrofluid of course but have never heard it explained. It is for cooling purposes? Can someone tell me what it is made of or how it is made?

Nightfall

Any new viscosity has to be closer to original than sludge.

westmassguy

Nightfall wrote: »

Any new viscosity has to be closer to original than sludge.

True, but how do you remove magnetic sludge from the gap between the pole piece and the surrounding magnet?

westmassguy

littlewoodboats wrote: »

I have heard of ferrofluid of course but have never heard it explained. It is for cooling purposes? Can someone tell me what it is made of or how it is made?

https://en.wikipedia.org/wiki/Ferrofluid

mikeyb128

Should check out the videos on YouTube of ferro fluid sculptures. Super cool!

Nightfall

westmassguy wrote: »

Nightfall wrote: »

Any new viscosity has to be closer to original than sludge.

True, but how do you remove magnetic sludge from the gap between the pole piece and the surrounding magnet?

I don't know. Any ideas? Some Googling lead me to this, he uses a q-tip, alcohol, and what looks like masking tape? Skip to 17:35 maybe you know what it is for sure.

https://www.youtube.com/watch?v=wtfqarUiFhw

littlewoodboats

Thanks Dave. Interesting article. It seems the magnetic properties of the nano particles actually change with temperature. As the fluid closest to the magnet structure increases in temperature the magnetism reduces causing the warmer fluid to migrate away from the magnet where it can cool. Pretty cool considering it was first developed as a zero G fuel.

westmassguy

Nightfall wrote: »

westmassguy wrote: »

Nightfall wrote: »

Any new viscosity has to be closer to original than sludge.

True, but how do you remove magnetic sludge from the gap between the pole piece and the surrounding magnet?

I don't know. Any ideas? Some Googling lead me to this, he uses a q-tip, alcohol, and what looks like masking tape? Skip to 17:35 maybe you know what it is for sure.

https://www.youtube.com/watch?v=wtfqarUiFhw

Looks like painters tape.

westmassguy

littlewoodboats wrote: »

Thanks Dave. Interesting article. It seems the magnetic properties of the nano particles actually change with temperature. As the fluid closest to the magnet structure increases in temperature the magnetism reduces causing the warmer fluid to migrate away from the magnet where it can cool. Pretty cool considering it was first developed as a zero G fuel.

Cooling and damping properties.

littlewoodboats

westmassguy wrote: »

Cooling and damping properties.

Yes, and it changes its magnetic state with temperature to self rotate to aid in its own cooling. Fascinating stuff

tonyb

Seems to me if the ferrofluid was meant to be changed, it would have a drain plug and a dipstick.

zarrdoss

I was researching this subject as a few of my speakers are past the 20 year mark and wondering if anyone here has actually changed out the ferrofluid in their tweeters? If so what changes did you notice? I have taken other 20+ year old tweeters apart and found an abundant amount of what appeared to be normal viscosity ferrofluid. It seems to be pretty stable and would imagine extreme heat to be its worst enemy. Or fluid made of poor quality if there is such a thing.

zarrdoss

OK I decided to just crack one open and have a look. Still fluid in them but you can definitely tell where it has leaked out. I will probably just get some new and replace it in both and not have to worry about it for 20 more years.

zarrdoss

I also pulled my Sony ES SS M7 apart and found no fluid in the VC gap or on the VC itself, it has all ran to the back of the magnet, I think because of their sloped front baffle, and the fluid itself has broke down over time. It is safe to say that yes ferrofluid should be something to consider in 20+ year old speakers. B&W recommends changing it every 10 years from what I hear. And from reading some reviews of the stuff they sell at Parts Express B&W even recommended buying it from there to a customer. Out of all the mods we do here this should be an easy one and crucial.

F1nut

Since this thread has been resurrected and since the original question was primarily in regards to the original Peerless tweeter I asked Ken, who asked Stu and the answer is no ferrofuild in the original Peerless.

Nightfall

That is interesting... thanks for the leg work Jesse.