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  #16  
Old 02-14-2012, 02:14 PM
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Quote:
Originally Posted by Kahoona View Post
Hi
I have a flat tweeter from an SB-M5
http://www.audiokarma.org/forums/sho...ght=Ferrofluid
That I am thinking of trying to repair. I can tell you that the Ferrofluid that was in the gap was thicker than molasses and actually pulled a couple of winds of wire off of the coil when I removed it. I remived as much as possible while using only a Q-tip lightly dampened with mild soapy water.If I can find the break in the coil I may try to repair it but the big question is will the Ferrofluid short out the repair to the gap walls rendering it useless? Do I seal the solder joint and how?? This tweeter is unavailable and rare and I would love to do the repair and have working again. Can anyone direct me to any info on working with Ferrofluid or offer any advice? I could then be able to tell you how the repaired tweeter with new FF compares to the other original one.
I recall checking out your post. VC on yours looks burnt, judging by the images anyway. There are a few sellers on eBay with the stuff. It's not cheap, but not terribly expensive either. Quantity certainly is a question since VC diameter is only one factor. There's depth and how much vacant space inside the "chamber" since it's not just a gap you'll be filling. I'm thinking, out loud of course, that since it's magnetic in nature and it doesn't pour out of the gap, the only issue would be overfilling? I guess you could fill the "chamber" (rubbing alcohol?) till full, then pour that into some kind of measuring cup, preferably small with many graduations. Any amount less than that should be effective enough.

Does anyone know if there needs to be an air pocket for compression (when the cone/dome, travels inward)? If so, then certainly less than measured. Maybe we'll work out the science here?
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  #17  
Old 02-14-2012, 02:48 PM
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Quote:
Originally Posted by Copa1934 View Post
I recall checking out your post. VC on yours looks burnt, judging by the images anyway. There are a few sellers on eBay with the stuff. It's not cheap, but not terribly expensive either.
Hi
Thanks for the reply. Yes it is burnt on one side . Does this mean that it is not reparable, particularly since it would be submerged in conductive liquid after repair?
Are you talking about replacing the coil and it's Mylar tube section only and keeping the original holder and flat honeycomb diaphragm?Wow. That would be an adventure for sure!
The Ferrofluid comes in single use packets according to coil diameter. I checked that out. You empty one packet into one gap. The fluid in these did not come close to filling the entire gap, just the lower area where the coil was.so that would not be a problem and the other one should be done.
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  #18  
Old 02-14-2012, 03:15 PM
Bellair Bellair is offline
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Ferrofluid was a major advancement 40 years ago....nowadays I look for tweeters without it because it tends to over dampen and lacks "life" The Vifa ring tweeters are a good example of no ferrofluid.
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  #19  
Old 02-14-2012, 03:42 PM
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Whew! Tried to solder coil wire but just too small for my big hands and short patience. Looks like we may have an Orphan Speaker and some parts for Barter town!
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I don't care anymore,no no,no no"
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  #20  
Old 02-14-2012, 09:01 PM
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Who was the first to use ferrofluid in tweeters?
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  #21  
Old 02-15-2012, 09:59 AM
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Quote:
Originally Posted by dowey View Post
how long is the average life span on these? how can you tell if they are bad or dried up? thanks...
There are hundreds of types of magnetic fluid, each of which has a different life span under different conditions. Also, not all driver designers know, or have the freedom to apply, best practices. Properly selected and used, a fluid-filled tweeter can last 40 years with very little degradation. On the other hand, many people find their tweeters shot after less than 10 years. (When mag fluids were first introduced, some over-enthusiastic manufacturers erroneously used water-based formulations and/or paper formers, which lasted weeks or less.)

The easiest way to check the condition of the fluid is to run an impedance curve and look at how much bump there is around resonance. Ideally, this should be compared to both a working reference and a non-filled unit. Still, simply looking at the curve can usually tell you a fair amount.

-k
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  #22  
Old 02-16-2012, 12:01 AM
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The fluid was also used for damping, so when it dries up the driver will obviously change.
There is some school of thought that the fluid inhibits the sound in a negative way.
Personally I always thought the ferro fluid as a compromise, the driver/ compliminting drivers and crossover should be designed with a power rating in mind that shouldn't require cooling fliud.
Probably why I prefer the Great Heil, stick a fuse on it, drive with a nice amp that doesn't clip right away and your good to go. Plus they easily outpreform any domes or cones I have heard in the last 40 years or so.
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  #23  
Old 02-16-2012, 12:15 AM
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I think most forum users assume ferrofluid is used to prevent voice coils from over heating. It also dampens resonance. I think this became a secondary and complimentary affect to protect the tweeter at lower crossover frequencies.

Does having lubricated voice coils on the tweeter slow transient response.

It has been stated it does.

Having the lowest tweeter inductance should increase transient response compared to tweeters with higher inductance values.

What effect does having tweeters with ferrofluid have in auto sound during freezing temperatures. Do you have to let the tweeters warm up. And what would be the correct method in doing this?

I have learned never to assume anything.
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  #24  
Old 02-17-2012, 10:47 PM
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  #25  
Old 02-17-2012, 11:18 PM
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I bought some T/E 360's and when I went to refoam the mids the ferrofluid had dried and turned so stiff the cones wouldn't move, they felt like frozen Polk drivers. I had to wash out the residue with acetone.
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  #26  
Old 02-18-2012, 06:55 AM
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again ferrofluid isnt only used in tweeters. my epicure 3.0 not only have ferrofluid in the tweeters but the midrange have ferrofluid in them as well. the woofer did not have any as i could see.
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  #27  
Old 02-18-2012, 10:09 AM
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I want to ask the question someone else did, who was the first to use ferrofluid in their tweeters? I was thinking maybe Genesis, but am curious as to who did it.
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