Bonzo Posted August 17, 2014 Share Posted August 17, 2014 I purchased a pair of K-79-K tweeters, one with a known dead diaphragm. I was not concerned as I had a spare set of working diaphragms. I pulled the horn and diaphragm off the magnet structure and checked the gap. I found it was full of an unknown dark liquid? I cleaned it out as best I could and put in a working diaphragm. It read zero DCR on my multi-meter. I placed it in the other tweeter and it read 9.3 ohms. To the best of my knowledge there is no ferrofluid or any other liquid used in this tweeter. Has anyone had a similar experience or have a clue on what is up with this driver and, maybe how to fix it? Any help would be appreciated, thanks! Quote Link to comment Share on other sites More sharing options...
mungkiman Posted August 17, 2014 Share Posted August 17, 2014 Hopefully, someone with more experience will chime in, because I thought the k-79-k did have ferrofluid. Quote Link to comment Share on other sites More sharing options...
Bonzo Posted August 17, 2014 Author Share Posted August 17, 2014 Hopefully, someone with more experience will chime in, because I thought the k-79-k did have ferrofluid. You could be right and that would make sense. Quote Link to comment Share on other sites More sharing options...
jjptkd Posted August 17, 2014 Share Posted August 17, 2014 I have come to the conclusion that the difference between the K-75 (Forte) and K-79(2) is the Ferrofluid. I've had many sets of each, the K-792 being the pro version and I assume it helps with peak power handling. Quote Link to comment Share on other sites More sharing options...
Bonzo Posted August 17, 2014 Author Share Posted August 17, 2014 I did notice there is a sticky substance around the plate on top if the magnet structure of the K-79's in my Chorus II's. I can only assume it's ferrofluid or something like it. If so, this is bound to be an issue for those who have that tweeter in their speakers, especially if you drive them hard and/or live in a warm climate. I wonder if there is a way to take that plate off and fix the problem? To my knowledge, there is no suitable replacement for the K-79? Quote Link to comment Share on other sites More sharing options...
jjptkd Posted August 17, 2014 Share Posted August 17, 2014 The K-75 from the Forte models are the same tweeter as the K-79 minus the fluid and are much more common. Quote Link to comment Share on other sites More sharing options...
jjptkd Posted August 17, 2014 Share Posted August 17, 2014 (edited) The fluid is meant to direct heat away from the coil allowing them to handle stress a little better than without the fluid. Either way you can clean the fluid out if you don't want it in there, rubbing alcohol should do it. Edited August 17, 2014 by jjptkd Quote Link to comment Share on other sites More sharing options...
Bonzo Posted August 17, 2014 Author Share Posted August 17, 2014 The fluid is meant to direct heat away from the coil allowing them to handle stress a little better than without the fluid. Either way you can clean the fluid out if you don't want it in there, rubbing alcohol should do it. Thanks, I think dried up fluid may be the cause of the non-working tweeter. I put some rubbing alcohol in the gap and will let it sit for awhile. Hopefully that will fix the problem. I will report back with my findings. Quote Link to comment Share on other sites More sharing options...
Bonzo Posted August 18, 2014 Author Share Posted August 18, 2014 After soaking it for about an hour and letting it dry, I didn't get much of anything out of the gap. I tried putting a couple of diaphragms in it and nothing. I am open to any suggestions of where to go next, thanks. Quote Link to comment Share on other sites More sharing options...
jjptkd Posted August 18, 2014 Share Posted August 18, 2014 Did you run anything through the gap? A folded post it (sticky part out) or tape folded so the sticky side is out push into the gap and circle it around to be sure there is nothing in there. It wouldn't hurt to use compressed air either if you have it available. Also, are you sure the two diaphragms you have are good ones? I've recently experienced something similar and later realized that both were bad, they were used though. The fluid itself will not cause a short, it must be a left over piece of coil from the original diaphragm if anything. Shine a light in the gap and see if anything is in there. Quote Link to comment Share on other sites More sharing options...
Bonzo Posted August 18, 2014 Author Share Posted August 18, 2014 Did you run anything through the gap? A folded post it (sticky part out) or tape folded so the sticky side is out push into the gap and circle it around to be sure there is nothing in there. It wouldn't hurt to use compressed air either if you have it available. Also, are you sure the two diaphragms you have are good ones? I've recently experienced something similar and later realized that both were bad, they were used though. The fluid itself will not cause a short, it must be a left over piece of coil from the original diaphragm if anything. Shine a light in the gap and see if anything is in there. I did everything I could to clean the gap and I don't see anything obvious inside. The diaphragms are good, I tried them in the other tweeter and both read 9 ohms +/- DCR. I will keep trying. Quote Link to comment Share on other sites More sharing options...
MikeFord Posted August 19, 2014 Share Posted August 19, 2014 Rubbing alcohol is my least favorite solvent, contains glycerin and diluted with water. Disinfectant alcohol in as full of strength (not diluted with water) is usually a better choice, but only from the stand point of leaving a residue. If rubbing alcohol did not work, you need some other solvent. As mentioned, none of the goop should result in a shorted voice coil, something else is doing that. I would sort that out first. Quote Link to comment Share on other sites More sharing options...
moray james Posted August 23, 2014 Share Posted August 23, 2014 fero fluid as far as I know is made with mobil synthetic as the base lubricant. Quote Link to comment Share on other sites More sharing options...
djk Posted August 23, 2014 Share Posted August 23, 2014 "fero fluid as far as I know is made with mobil synthetic as the base lubricant." Where do you come up with these strange notions? Synthetic esters typically provide higher thermal stability than synthetic hydrocarbon oils. https://ferrofluid.ferrotec.com/about/ferrofluid/ Quote Link to comment Share on other sites More sharing options...
oldtimer Posted August 24, 2014 Share Posted August 24, 2014 very interesting. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.