The ferrofluid dilemma: fact or fiction?
- Thread starter Jayrosc
- Start date
The Energy 22s are a classic tweeter for that issue .... but also rather fragile too and doesn't like to be driven hard by lower-power clipping amps (what self respecting tweeter does?!)
Many of the Seas tweeters are ferrofluid filled ... so I don't think the 87H (i.e. Dynaco A25) are but the H253 tweeters in my Paisley Research AE-400 speakers are ferrofluid filled.
Which brings up another comment .... I had the same H253 tweeters in another pair of Paisley Research ... and the woofers were ferrofluid filled too ... and one had failed.
Many of the Seas tweeters are ferrofluid filled ... so I don't think the 87H (i.e. Dynaco A25) are but the H253 tweeters in my Paisley Research AE-400 speakers are ferrofluid filled.
Which brings up another comment .... I had the same H253 tweeters in another pair of Paisley Research ... and the woofers were ferrofluid filled too ... and one had failed.
milanomike
Well-Known Member
Yeah, that's the video I saw. But once you have tweeter out, follow the procedure to pop the dome cover and plate off. Use index cards or printer paper cut into strips to fit in gap. Do this until goo is mostly gone. I found dipping printer paper in alcohol (a cheap blend, not a single malt, seriously, std rubbing alcohol here) helped the process. Buy the amount for the size tweeter you have, i.e. 1" and squeeze it in. Takes like 15/20 minutes per tweeter taking your time
MJB1959
Super Member
You might have been reading some of the ADS threads that have been posted along the way, the ADS family of speakers used the dome tweeters and midranges in many of their models, the company is no longer, and the speakers at this point are nearing the 30-40 year old mark. invariably the ones that were employing the ferrofluid began to dry, causing audible losses. The owners are the last to notice as it is typically a gradual issue of time, I have had some of my ADS domes rebuilt and restored to original specs and that included new ferro as well as dome material and voice coils and after a gentle break in period, they are sounding great. I know I am not the only one here that can attest to the marvels of renewing your ferro fluid.
You may also want to find out if there's ferrofluid in your drivers before you attempt anything. Per Richard So there's no ferro in ADS's 1530's mids and tweets.
I fried a 1" Vifa soft-dome, pulled it apart and see that there's no fluid. The other one, which did not fry, still has fluid.
So the chicken or the egg? Did a transient that opened the coil also evaporate the fluid? I doubt it and presume that the fluid was gone first. It did prompt me to check and replace the fluid in some other speakers that I have, just to be sure.
So the chicken or the egg? Did a transient that opened the coil also evaporate the fluid? I doubt it and presume that the fluid was gone first. It did prompt me to check and replace the fluid in some other speakers that I have, just to be sure.
I went on a ferrofluid replacing binge about a month ago. The highs came back in a big way. The Seas drivers on my Mission 770s were a bit harsh though. Disappointing. BUT! I am happy to report that they smoothed out beautifully over the last month. They perform beautifully now. I have never been happier with my Missions.
In conclusion, it appears that there is some break in after a ferrofluid replacement. Because the tweeters are so much sweeter!!!
I can not explain this scientifically though...
In conclusion, it appears that there is some break in after a ferrofluid replacement. Because the tweeters are so much sweeter!!!
I can not explain this scientifically though...
Last night I replaced the ferrofluid in four of my Energy Pro 22 tweeters. In three of them the fluid was good but in one the fluid turned thick and tar like. It was the last of the four I did and by the markings on the tweeter it appeared to have even serviced in 2003. It is not hard to imagine how the gummy ferrofluid would cause tweeter failure by restricting its movement.
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Good Hifi
New Member
Wat there a muck in the gap?
oksailor22
New Member
I know this is an old thread, but I'm looking at the Ferrofluid cooled mid ranges in my Marantz SP1500's they are sounding very dull and over dampened. these speakers are sealed and not made to take apart. I've purchased an extra one to experiment on. and I'm going to try to reconstitute the FF by injecting some kerosene ( a small amount) through the cone into the gap between the magnet and voice coil. I will then face the speaker up (so gravity helps me) and run the speaker at a low current around 500hz or so to see if I can get the kerosene to mix with the gummy FF. I don't have any test equipment to check the drivers current performance, so this may be somewhat arbitrary, but if it makes a physical and audible improvement, that will be considered a success by me. I've not seen anyone on the web attempting this. but as far as I can research stable kerosene is an oil base that is frequently used in making FF. It has about twice the viscosity of water.
I'm certainly open to suggestions if anyone has different ideas....
Also, I've not been able to find a frequency response graph for these speakers anywhere, so if any one has or knows of one, that would be awesome to have. Thanks Mark
I'm certainly open to suggestions if anyone has different ideas....
Also, I've not been able to find a frequency response graph for these speakers anywhere, so if any one has or knows of one, that would be awesome to have. Thanks Mark
Which driver are you attempting to repair? Midrange? Tweeter? Do you know what type of ferrofluid it originally used?
Do you know if the ferrofluid has become more viscous? Can you move the cone and see how it behaves? What measure / test are you using to determine it's overdamped (not dampened, that would be moisture)?
Ferrofluid was available in various quality when your marantz speakers were built in Korea, I doubt that they used a high quality fluid, but hard to tell.
If the fluid was a cheaper oil base, it very well might have softened the voice coil and become a gummy mess. The iron particles might have come out of suspension allowing the fluid part to run out, and it is also possible that the fluid base has become oxidized or evaporated. Without knowledge of what was used it is hard to prescribe a solution to repair it. Modern ferrofluid and that used by higher-end speaker manufacturers is typically polyolester or other synthetic carrier with a very good fine iron particle that stays in suspension. I realize that you're dealing with cone mids and tweeters that can't be disassembled, but it seems like introducing a solvent into the coil cap could be a problem if it further dissolves or swells the varnish on the coils. Not sure this will move you forward.
OTOH, if there's little financial risk, IE the speakers aren't worth much as-is, I guess it's worth a try provided you're not creating a flammable solution where electricity resides.
I'd do some testing to ensure that this is the problem before moving forward.
Also, in higher-end speakers the ferrofluid in tweeters is used to tune the response, and it is how the tweeters are matched. This matching is extremely important for imaging, and is difficult to reproduce for those of us with a screwdriver and a squeeze-pack of fluid. I do not recommend replacing ferrofluid as a regular maintenance like you are rotating tires on a car, if it's working then leave it alone IMO. You can test the tweeters with a good tone generator and calibrated mic, free programs are available for your computer to do this. If they meet original specs/curves I'd say they're fine.
Do you know if the ferrofluid has become more viscous? Can you move the cone and see how it behaves? What measure / test are you using to determine it's overdamped (not dampened, that would be moisture)?
Ferrofluid was available in various quality when your marantz speakers were built in Korea, I doubt that they used a high quality fluid, but hard to tell.
If the fluid was a cheaper oil base, it very well might have softened the voice coil and become a gummy mess. The iron particles might have come out of suspension allowing the fluid part to run out, and it is also possible that the fluid base has become oxidized or evaporated. Without knowledge of what was used it is hard to prescribe a solution to repair it. Modern ferrofluid and that used by higher-end speaker manufacturers is typically polyolester or other synthetic carrier with a very good fine iron particle that stays in suspension. I realize that you're dealing with cone mids and tweeters that can't be disassembled, but it seems like introducing a solvent into the coil cap could be a problem if it further dissolves or swells the varnish on the coils. Not sure this will move you forward.
OTOH, if there's little financial risk, IE the speakers aren't worth much as-is, I guess it's worth a try provided you're not creating a flammable solution where electricity resides.
I'd do some testing to ensure that this is the problem before moving forward.
Also, in higher-end speakers the ferrofluid in tweeters is used to tune the response, and it is how the tweeters are matched. This matching is extremely important for imaging, and is difficult to reproduce for those of us with a screwdriver and a squeeze-pack of fluid. I do not recommend replacing ferrofluid as a regular maintenance like you are rotating tires on a car, if it's working then leave it alone IMO. You can test the tweeters with a good tone generator and calibrated mic, free programs are available for your computer to do this. If they meet original specs/curves I'd say they're fine.
oksailor22
New Member
Thanks Jeff
I'm working on the midrage 5" driver. The tweeters are still working well enough at present, but the mid is just about missing completely. the only reason the speakers are listenable is that the woofer (15") is crossed over at 900hz which sounds crazy high since it supposedly a 18hz free air resonance.... On the mids the cones are very reluctant to move much at all.... I have no idea what viscosity the fluid was originally as I can find very little information on these speakers period.
I do have a replacement speaker picked if I just end up trashing these. Celestion tf0510 looks to be a fairly good match. sensitivity is in line as is the power handling and ohms as well. They are not too pricey as well, so I may go that direction, but just thought I would try to revive these before I just trash them. they are in excellent condition otherwise I would not even try.
I'm working on the midrage 5" driver. The tweeters are still working well enough at present, but the mid is just about missing completely. the only reason the speakers are listenable is that the woofer (15") is crossed over at 900hz which sounds crazy high since it supposedly a 18hz free air resonance.... On the mids the cones are very reluctant to move much at all.... I have no idea what viscosity the fluid was originally as I can find very little information on these speakers period.
I do have a replacement speaker picked if I just end up trashing these. Celestion tf0510 looks to be a fairly good match. sensitivity is in line as is the power handling and ohms as well. They are not too pricey as well, so I may go that direction, but just thought I would try to revive these before I just trash them. they are in excellent condition otherwise I would not even try.
Sounds well worth the effort.
oksailor22
New Member
well, it could be that I just trash the driver (and I intend to do just that with the identical spare I bought off ebay. I'm planning on cutting a section out of the cone so that I can see what is in there and how it reacts to the additional kerosene. If it all works ok then I can set up a post with pics and instructions of what and how I did it, and maybe we can save some vintage speakers... Thanks for the support. I will post an update positive or negative when I get it done....
frommerstop
Super Member
I have KEF R107/2s, had them since new, other than needing woofers refoamed a couple years ago, they’ve been without issue. I decided to try replacing the ferrofluid. The old fluid was nasty & black, but cleaned up easily enough. New fluid installed... No noticeable change!
I suspect, and it’s only my theory, that if the speakers are in constant use, like mine, there isn’t much benefit in new fluid. If the speakers have been sitting around, largely unused for years, the gummed up old fluid may be causing more trouble. If the speakers have been in continuous use, like mine, it may not matter much.
I suspect, and it’s only my theory, that if the speakers are in constant use, like mine, there isn’t much benefit in new fluid. If the speakers have been sitting around, largely unused for years, the gummed up old fluid may be causing more trouble. If the speakers have been in continuous use, like mine, it may not matter much.
willy k
Member
I have a pair of Dahlquist CA1/W1 speakers that were made in the early 90's that I bought used in the late 90's. They started to sound lifeless in the high end a few years back. I took the tweeters apart and noticed that the ferro fluid was a thick greasy mess with a slight burnt smell. I rarely listened to these speakers at high volume (although I have blasted some stones at volume a few times). I cleaned the fluid out of the gap with paper towels dampened with naptha, and cleaned the voice coil gently with a Q-tip dampened with naptha. I have been running them with no fluid in the gap. The cleaning helped a bit and brought back some treble, but they are still not there, still lacking in treble. I plan on adding the fluid and doing a recap. Seeing the thick slop that came off those parts, there is no doubt that this issue would dampen he driver from vibrating back and forth thousands of times a second. i'm looking forward to hearing more opinions on this subject.
oksailor22
New Member
Ok, I dissected my Marantz midrange driver that I got off ebay, guess what... the fluid was ok, The stiffness of the cone was due to the speaker being sealed, so my drivers are ok! This led me to investigate further and found that the crossover network needs rebuilding. the Marantz sp1500 has a 2nd order crossover with some interesting specs and so I may want to improve on these. I'm still looking for any driver specs and or even a response curve for the entire speaker, but so far I've not found that Information.
Any help would be appreciated.
thanks Mark!
Any help would be appreciated.
thanks Mark!
What was used for capacitors in the crossovers? Take a picture of the crossover also. If electrolytic caps were used they may have dried out and out of spec. You can replace with tighter tolerance polypropylene types. Also test the resistors.
Is there any protection on the mids and or tweeter? Some speakers used poly switches, fuses, circuit breakers, light bulbs, etc. The last pair of speakers I restored, several of the old cement brick resistors were out of spec, I haven't seen that very often, several of the electrolytic caps were out of spec, and the poly switchs used to protect the tweeter had degraded and read 3.7 ohm instead of .5 ohm. If any of the components are out of spec, this will shift the crossover points. I would test and rebuild the crossovers as needed first before using random drivers. You may wind up with the same problem.
oksailor22
New Member
this crossover is just crazy, the first thing I noticed is the midrange polarity is purposely wired backward.... I thought it was maybe a mistake, but then found a service manual and the wiring diagram says the + input is running to the - side of the midrange..
wow....see pics below... I don't think I would do this!
wow....see pics below... I don't think I would do this!
