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Old 5th March 2013, 09:12 AM   #11
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Seeing how quickly ferrofluid damped tweeters fail with solidifying ferrofluid, this is just a bad idea
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Old 5th March 2013, 10:31 AM   #12
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Quote:
Originally Posted by Brett View Post
You could get even better performance and longer life from drivers by designing or modifying them to have a heatsinking system that passively or actively removes waste driver heat to the outside of the box.

A passive approach was detailed by Wayne Parnham years ago, here and with more links here.
A bit like Volt does with their radial drivers?
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Old 5th March 2013, 10:59 PM   #13
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Default Been Done for Years....

Many of the models up and down Community's line are Ferrofluid Cooled. The Solutions Series in particular comes to mind. The sound very good and get unbelievably loud. I think the SLS960 can hit over 140 dB SPL. Even their old CSX series cheapo boxes had FF cooled woofers if memory serves.

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Old 5th March 2013, 11:17 PM   #14
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davidsrsb,
Where do you come up with the solidification information for a ferro fluid? I find that hard to understand from a basic chemical process. The fluid is an oil and unless there was a loss of a component due to evaporation or some secondary source of contamination how do you turn an ester based oil into a solid? Do you have actual experience of this or is this anecdotal information you are reading somewhere? I am very curious where this information is coming from, there are way to many devices with ferro fluids in commercial use to believe this is a common occurrence.
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Old 5th March 2013, 11:58 PM   #15
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I'm unaware of hardening of the synthetic "oil" base in ferrofluid.

Someone could inquire of Ferrofluidics or whatever the name of the company that bought them is...

As far as cooling using pole pieces, this is common practice now for most Neodymium drivers since the neo magnets do not do well with heat.

There is probably something online about the application of ferrofluid in woofers. No doubt underhung VC designs would work better than over hung high xmax designs.

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Old 6th March 2013, 12:06 AM   #16
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Bear,
He is the link to the only company that I know of doing it in the USA. I assume that it is a rumor myself that the fluids dry out. I think it is more likely that a poor designed motor assembly allows the fluid to be pushed out of the gap and then the voicecoil burns and sticks to the pole piece. I would think you would have to overheat the fluid by a large factor to break it down to the point of failure. The new Corvette and Cadillac and Ferrari uses ferro fluids in the shock absorber, would they do that if it was going to harden like that, and I can assure you those shocks get damned hot in use.

www.ferrotec.com/products/ferrofluid/audio
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Old 6th March 2013, 01:29 AM   #17
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from http://en.wikipedia.org/wiki/Ferrofluid:
"the surfactant tends to break down over time (a few years), and eventually the nano-particles will agglomerate, and they will separate out and no longer contribute to the fluid's magnetic response"
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Old 6th March 2013, 02:14 AM   #18
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PeteMck,
One thing we learned in my college classes is that Wikipedia is an unreliable source of information and none of that information is vetted or confirmed. Anyone can add to Wiki, I could write just the opposite, that is just an opinion. I am not going to say that there may not be some bad ferro fluids out there from who knows where, but that is not American made ferro fluid doing that.
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Old 6th March 2013, 03:18 AM   #19
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My TDLs had one tweeter with a completely locked dome and one locked at one point on its coil. Frequency response was vary odd with no lower treble and a strong peak in high treble. The harmonic distortion measured very high. Careful dismantling and wiping out the very sticky ferrofluid got the tweeters going again with reasonable measurements.
My Mission 752 tweeters have similar high harmonic distortion and loss of low treble, but I have not managed to dismantle the tweeters yet to inspect the coils. These speakers have NEVER been played very loud.
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Old 6th March 2013, 03:52 AM   #20
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Davidsrsb,
The real question becomes where is the fluid that is used in these devices made? That is the real question. In the USA you can only use the fluid from Ferrotec, it is protected by patent. So my first response is that the fluid is a knockoff and though it may be a ferro fluid it has a problem with the chemistry. There are too many companies in the US that would be screaming if this was the case here as the warranty problems would be in the millions of dollars. There are to many speakers here that are decades old without the problems you speak of. I see the kits to inject your own fluid into a speaker and the price gives them away, they are priced below what you can purchase the fluid wholesale from the manufacturer here. There is a reason for that. This is counterfeit materials. I would bet money on that.
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