jheis Posted June 9, 2006 Share Posted June 9, 2006 I recently bought a pair of KG 4.5's which turned out to have a dead tweeter. I ultimately diagnosed the problem as a broken lead at the voice coil. The tweeters are K-86-K. In taking things apart, I found that the magnet gap was full of a dark brown gunky liquid. I tried to clean it out with the tip of a paper towel, but that just made a mess. So, being out in the garage, I grabbed a can of brake cleaner, sprayed the gunk out and then blew it out with compressed air. After doing a little research here on the forum (better late than never), I learned that the brown gunk was "ferro fluid" which is some type of oil that is supposed to help cool the voice coil. I ordered new diaphragms from Bob Crites & asked him about replacing the ferro fluid. The replacement diaphragms are, apparently, used in a variety of speakers - some use ferro fluid and some don't. So, Bob's advice was to clean out the other magnet the same way & leave the ferro fluid out. So, I guess the question is: is ferro fluid necessary and will it do any harm to leave it out? James Quote Link to comment Share on other sites More sharing options...
BEC Posted June 9, 2006 Share Posted June 9, 2006 Actually, I think leaving it alone in both drivers would have been the best thing to do. Since you had already removed it from one of the drivers, how to proceed from there is a bit more murky. I am not sure which way to lean on that issue. I am not even sure that putting it back into both drivers is the right way to go, if you had the ferro fluid to put in. After thinking about this some more, I suspect that you may have been able to remove most of he oily stuff the magnetic particles are suspended in, but may have left most of the magnetic particles clinging to the magnet structure. Perhaps someone else has some ideas on the subject. Bob Crites Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted June 9, 2006 Share Posted June 9, 2006 Well being my mildly educated guess but since the ferrofluid was designed for the actual driver I would think that removing it would heat it much quicker than without. Sorta like blocking the airvents of a computer. Sure it will work but if you leave them on for a long time expect it to thermally fail or so. I believe non ferrofluid designs usually have some other method of heat exchange and since you removed the oil now there is a layer of air which does not transmit heat very well at all. The problem now is finding ferrofluid that has the specific weight that came with the driver. That would almost be an impossible thing to find out unless someone in the know tells you. Is the ferrofluid magnetic because I thought that ferrofluid meant particles of metal non magnetized that would form a shape with a magnetic field. Also they are coated to make sure they do not stick to each other. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted June 9, 2006 Share Posted June 9, 2006 Some tweakers recommend removal of the ferro fluid from any driver claiming an improvement in HF clarity and imaging. Bob's right, use your cleaner to remove the oil from the other magnet assembly. When both are quite dry use Bob's folded Scotch tape method to clean as much of the iron particles from the gap as possible. When using your KGs, avoid underpowered SS amps. It is clipping from underpowering that is deleterious to tweeters more so than overpowering at deafening levels. Rick Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 11, 2006 Share Posted June 11, 2006 ferro fluid can be bought in small bottles. but re-applying is not as easy as it appears. issues is the qty...the more you put on, the heavier the coil becomes. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted June 11, 2006 Share Posted June 11, 2006 yes you can buy ferrofluid but you need to know what weight the oil is. Quote Link to comment Share on other sites More sharing options...
jheis Posted June 12, 2006 Author Share Posted June 12, 2006 The two new poly/fabric diaphragms I ordered from BEC last Thursday afternoon arrived today (thanks for the quick service Bob). Since I don't have any ferrofluid, I decided to just clean out the other magnet - so, at least they'd both be the same. These speakers are in my BR system, so they're never (well, hardly ever) going to be cranked. The new diaphragms have been installed and my new/old KG 4.5's are now firing on all cylinders. My $49.99 KG 4.5's are now $98.99 KG 4.5's, but still quite a deal. Now, I just have to do something about the cabinets.... James Quote Link to comment Share on other sites More sharing options...
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