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[Michael {Bink} Knowles]

I'm trying to find out who pioneered the use of ferrofluid as a cooling agent in the voice coil gap of compression drivers, which was the first application. A bunch of books and articles say that 1973 was the year, but they don't name the person or company.

[Tim McCulloch]

Binkster!  You're back!

My memory says "TAD" but I'm not certain that is correct.

1973 is a lot of brain cells ago...

[John Roberts {JR}]

Have you tried asking the manufacturer of ferro-poop...?

JR

[Mike Caldwell]

NASA invented it in the 60's.
Not sure who first had the idea to put it in a voice coil gap.

[Justice C. Bigler]

NASA invented it in the 60's.
Not sure who first had the idea to put it in a voice coil gap.

Probably some NASA engineer when he was home brewing his HiFi stereo system at home?

[Michael {Bink} Knowles]

Have you tried asking the manufacturer of ferro-poop...?

JR

Not yet. I understand Ferrofluidics in Burlington, Mass, put out a sample kit in 1973, so they're definitely on the early side.
https://www.czferro.com/ferrofluid-history

[Michael {Bink} Knowles]

... And this patent says "the 'Newsreports' section in Electrimechanical Design, October 1973 describes the use of Ferrofluids to seal the space between the poles of a loudspeaker."

https://patents.google.com/patent/US4017694A/en

[Michael {Bink} Knowles]

This Ferrotec page says "The first commercial use of ferrofluid in loudspeakers was 46 years ago, in 1973." I'll shoot them an email and ask who it was.


http://www.loudspeakerindustrysourcebook.com/united-states/bedford/liscategories/ferrotec-28usa29-corporation

[Douglas R. Allen]

I'm trying to find out who pioneered the use of ferrofluid as a cooling agent in the voice coil gap of compression drivers, which was the first application. A bunch of books and articles say that 1973 was the year, but they don't name the person or company.

I seemed to remember Radio Shack using it in their speakers back in the early/mid 1970's. I had a set of Mach 1's when they first came out and they did mention liquid cooling that I believe they said was oil but that was a few years ago.

Douglas R. Allen

[Michael {Bink} Knowles]

Ferrotec responded to my email in 36 minutes! Wow.

Marketing specialist Vanessa Rene at Ferrotec says that Bob Berkowitz of Acoustic Research began studying ferrofluid in 1972, using it to damp resonance of a tweeter. Fred Becker and Lou Melillo of Becker Electronics were also early adopters in 1976. Panasonic was the first Asian manufacturer to put ferrofluid in commercial loudspeakers, in 1979. The field grew rapidly in the early '80s, with Meyer Sound, Apogee Sound and many more jumping in.

Other archival sources show that Dana Hathaway of Epicure in Massachusetts was using ferrofluid for tweeter damping in '74, and he noticed the cooling mechanism.

By 1979, Showco was putting ferrofluid in woofers for the cooling effect.
https://books.google.com/books?id=fAEAAAAAMBAJ&pg=PA61

[ProSoundWeb Community]