Ferrofluid also works for keeping voice coil cooler... and also used for dampening sound. used in tweeters and midrange drivers usually. Check my EON 610 Repair video as I show the voice coil fail in a spot that was not getting cool because stock ferrofluid was inadequate

Not snake oil , tweeter oil

Paul, I just wanted to tell you how much I appreciate the effort you make to provide these entertaining and informative videos ever single day. I know it can be difficult to find the time and I thought I'd let you know that I enjoy them very much. Thank you!

I watch every video you post because you CAN talk to us audiophiles in such a fun and non technical way that it's just a pleasure listening to you. Best regards from Tehran where many audiophiles live...

I think ferro fluid was first used in loudspeaker drivers by Acoustic Research in the mid 1970s in their tweeters for the model 10 pi and 11. These speaker systems were further refinements of AR3a. Cooling voice coils especially in tweeters is critical. Not only does ferro fluid increase power handling capacity but voice coils increase their electrical resistance when they get hot. This results in thermally induced dynamic compression. There's another good reason to use multiple tweeters. Heat is generated proportionally to the square of the current.

Ferrofluid is really common in pro audio where extreme power handling is a thing

my original Advent 2 have Ferrofluid tweeters but not the woofers, the tweeter moves much faster and creates heat, cant wait to see what you come up with for your line of PS Audio speakers. had to replace the woofer surrounds twice before with the original voice coils , hope I can afford the new middle line...thanks Paul

I took apart a couple tiny laptop speakers for the neodymium magnets but found that there was brown oil inside. I had no idea what it was until some KZfaq video about ferro fluid had mentioned it was used it tweeters.

Curie Temperature of magnets - typically around 700 °F for rare earth magnets where at this temperature they will loose their magnetic property.

Oil liquid with particles of iron which cools dynamic twitter. It's good to be replaced every 20 years ... or when you hear that the twitter has become tamed (obscured).

I thought it was used to create an infinitely small gap between the coil and the magnet for efficiency, which also goes toward cooling.

I believe some drivers that used Ferro fluid weren’t sealed and as a result would seize the drivers with dust and dampening material getting in and creating glue

The Kef 104/2 I had used ferrofluid in the tweeter.

You gave me an idea, Paul. Tube power amps with a super-cooled output transformers and super-cooled speaker magnets!

I'll add fuel to this fire: After watching this video I was surprised to see that Paradigm's new Persona speakers use ferro-fluid, specifically in the tweeter (as per other comments below) even though the tweeter and the mid-woofer are both beryllium drivers. Paul didn't note any detriment to using ferro-fluid; just that it's not seen as often any more. But Paradigm's is a very recent implementation. I wouldn't mind Paul's input on what technological advancements have occurred more recently after ferro-fluid was first introduced in audio: are there now better solutions, or are new materials just intrinsically not as prone to negative consequences of heat?

Didn't Acoustic Research use that?

I always thought f-fluid was more of a tweeter thing. Faster moving, smaller coils, tight spaces, more heat? Never seen a ferrofluid cooled woofer, but, who knows! PS Audio speakers? Sure, why not!

if vibration is the name of the game (generally speaking) do you see a radical evolution of speakers? beside the building upon the existing patterns of speakers.and im not talking about cabinets or omnidirectional speakers. im hoping for some new inventions given the new possibilities of technologies and creativity to implement something new.i know you and youre company work on something but what im interested in is something like electric cars vs petrol cars.i can only imagine the possibilities of digital control over many aspects.

i use to have some yamaha 3 was w ferro tweeters that sounded amazing should of never sold em

Well I had some ferro fluid and the doctor sent me to the GU clinic to keep the heat away,,,,!!! Strange,,,,!!!

Hi Paul. the MRI machines have magnets of superconductor (basically coils once pumped with energy and short-circuited (so the energy cycles inside of them). The crio-coolant is used not to keep the magnet cool but for keeping the coil material (wire) in the superconducting stage (near absolute zero). :) Have a nice day

I hear you cuss and get to the point, I hit like. Simple as that.

SVS PB Ultra 16 subwoofer has an 8inch voice coil and it's a solid driver. No need for ferrofluid.

I'm no mic expert to put it mildly but Paul your mic is clipping😮 Maybe mics can't clip?.. but there's definitely some distortion in the chain somewhere. I listen to these vids through my 2 channel Rega/Quadral system and it can get pretty nasty at times. Just sayin!

The biggest problem is ferrofluid is it still subject to Hoffman's iron law, simply put what you gain in power handling you lose in sensitivity so a properly designed transducer should not need ferrofluid to achieve any moniker of high Fidelity. Maybe I'm wrong and if so please feel free to explain to me why.

Do your research before the video.

I’d always assumed ferro-fluid was used in tweeters. Its big problem is that it dries out rendering the driver useless. Personally I’d avoid ferro-fluid drivers, they’re a problem waiting to happen.

Oh boy... The magnet coils of an MRI are kept cold with liquid helium and the He boil off is slowed by an outer cryogenic jacket of liquid nitrogen. The coils need to be kept cold because superconducting wire (which superconducts only at very low temps) is used to generate the magnetic field. There are no permanent magnets (where The Curie point is relevant) in most modern MRI systems (certainly not any of the human imagers found in hospitals). Lastly, it was Pierre Curie that the Curie point/temperature is named after, not his wife.

Hey Paul, NASA has an article about this on their site! This video prompted me to look it up spinoff.nasa.gov/Spinoff2015/cg_2.html "Speakers produce sound by sending alternating currents through a coil, which moves rapidly back and forth in relation to a permanent magnet. The coil’s movement vibrates the diaphragm, producing sound. A damper is typically a ring of any manner of materials, perhaps cardboard, paper, or silk, that fits around the coil to prevent it from wobbling and also to inhibit the diaphragm from blowing out. The downside of the damper, however, is that it can cause extraneous vibrations that can distort sound and lower overall volume capability. Sony’s solution was to replace a solid damper with ferrofluid. The result, according to the company, is a better speaker. “The ferrofluid provides a free-flowing movement for the speaker to deliver sound without the vibration of a traditional damper, which minimizes some of the accuracy of the sound reproduction,” says Rob Manfredo, a communications specialist with Sony. “The lack of dampening also means you get three decibels more in volume.” The firm’s in-house research and development group also claims that efficiencies created by the fluid decrease energy use by 35 percent." Also here's a link for Sony's own info: bit.ly/2PHtosA

Doesn't Google work or what?