What is Ferrofluid?
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- Опубликовано: 13 дек 2018
- Ferrofluid in loudspeaker drivers was all the rage years ago. What is it and is it really a magic potion for speaker performance or BS? Have a question you want to ask Paul? www.psaudio.com/ask-paul/
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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.
Got your facts a little mixed up. Epicure used it in their speakers, i.e. the Epicure 11, no real relation to Acoustic Research.
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
Ferrofluid is really common in pro audio where extreme power handling is a thing
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 RUclips video about ferro fluid had mentioned it was used it tweeters.
I thought it was used to create an infinitely small gap between the coil and the magnet for efficiency, which also goes toward cooling.
Wow... I never thought of that. You’re right though. It would certainly have an effect on magnetism. The benefits would outweigh the frictional losses in speakers that don’t move very far, such as tweeters.
Keep in mind that this guy isn’t perfect, and as much as he knows, he lacks a lot of knowledge. Most of what he says is simply opinions and perspectives, and nobody has every possible perspective... except god, the collective consciousness... 😏
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).
Didn't Acoustic Research use that?
The Kef 104/2 I had used ferrofluid in the tweeter.
Same with my C-40's.
I have (British) Spirit (by Soundcraft) Absolute 2 nearfield monitors, which have a 6,5" woofer and a soft dome tweeter with ferrofluid coolant. -Woofer looks a lot the same what B&W used on DM-series, suspension curved inwards but these have a dark blue paper cone.
Curie Temperature of magnets - typically around 700 °F for rare earth magnets where at this temperature they will loose their magnetic property.
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
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
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?
You gave me an idea, Paul. Tube power amps with a super-cooled output transformers and super-cooled speaker magnets!
You would have to be careful about added noise from the nitrogen cryo compressor. While your at it, find a way to make a coolant loop that passes through the plates of a tube to allow MUCH higher power dissipation. I’m fairly sure that plate temperature is the primary limiting factor of a tubes power output, but if it’s not, it would still help to improve its capabilities.
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!
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
True thats why you need dump resistors to extract the power once it quenches ....otherwise the whole thing will melt
didn't know about it. Though always when quench the energy goes into heat but not to this extent. I have only basic knowledge being at Bruker as a Trainee several years ago. Cool company.
e.g. uspas.fnal.gov/materials/17UCDavis/MachineProtection/uspas_mm.pdf page 37....nice to hear that you have worked with magnets aswell. I m working in a magnet devision at a particle accelerator facility.
Well I had some ferro fluid and the doctor sent me to the GU clinic to keep the heat away,,,,!!! Strange,,,,!!!
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!
He has been told that many times, but it seems he doesn't care about the sound of his videos, as absurd as that sounds.
this vid sounds fine on my Mac.
@@googoo-gjoob Have you got your Mac feeding a high quality DAC and headphones or feeding a resolving HiFi system? Don't tell me you're using the speakers on your Mac?!
@@mag-wp6yt i'd call my setup mid-fi. Musical Fidelity M1 DAC to MuFi dual mono M6i to B&W 804d2.
as he dips his head once in a while one syllable is louder than the rest...but doesn't quite clip.
Why would you waste your time watching a youtube video on a hifi system? Its youtube! I wont watch on anything other than a phone or ipad sometimes my computer at work.
I hear you cuss and get to the point, I hit like. Simple as that.
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.
It’s possible that ferro fluid increases sensitivity (viscosity frictional losses aside) by effectively closing the gap between the magnet and coil, extending and strengthening the magnetic field, since ferro fluid is essentially suspended iron. Even if the frictional losses negate the sensitivity gains, the fluid would provide more cooling and allow higher power operation. Tweeters don’t move in long strides like a subwoofer does, therefore, it moves less air and in turn, less air passes across the coil. Tweeters may benefit more from ferro fluid than other speakers, due to their lack of self cooling. Your assumptions are probably accurate for other speakers, like woofers and midrange drivers.
@@jjhack3r Thank you for the correction. I was totally forgetting about the tweeter side of things😂
It's very irritating when certain techs get misapplied in an attempt to achieve a goal and by then so much money has been spent the company's pawn off their failure to none knowledgeable people. So ya, tweeters ferro fluid ='s 👍
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.
IIRC high end tweeters do not (or at least did not) have ferrofluid , so avoiding them is a good thing soundwise , but not so good for your budget . I may be wrong coz I am an AirMotionTransformer type of guy
@@gerritgovaerts8443 Dynaudio Esotars are as high end as tweeters go and use ferro fluid.
@@zaldam As a counter example I can cite a very expensive (300 $ a piece) member of the Scan Speak Revelator series : www.madisoundspeakerstore.com/ring-radiator-tweeters/scanspeak-revelator-r2904/7000-09-tweeter-black-face-black-plug/
From the product description I quote : " Better dynamics are achieved by not using ferrofluid" .
I have nothing against Dynaudio , I actually used to admire them a lot when their drivers were still available to the DIY crowd . I even have advised people to buy Dynaudio speakers and I still love my Totem Signature speakers which I think have Dynaudio woofers (and a SEAS tweeter) . Scandinavian drivers are the best , but some German brands are OK too (Mundorf)
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.
Do your research before the video.
Doesn't Google work or what?
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