Infinity Polysherite Mid - Ferro-fluid?

BadjerJim · Aug 25, 2014

Question:
I have a pair of Infinity RS-6001, perfect shape, but were made back in 1989.
I've heard a rumor that the Polyspherite mids were injected with Ferro-fluid when manufactured. Is it possible/likely that this has dried out in these 25 years?

The 6001s don't quite have the midrange presence that I'd expect... which makes me suspicious. But these Polyspherite mids weren't made to be taken apart easily (unless someone knows a trick). I certainly don't want to screw them up by trying to take them apart if I don't have to.

Any advice or experience with Polyspherite mids? ?

A400 · Aug 30, 2014

I have RS6001s and had this problem with one midrange, the other is still working well. I confirmed an issue with test tones prior to deciding to operate. Apart from the difference in sound the vibration felt by touching the driver when playing music was much weaker on the bad driver.

There are three screws holding the motor to the frame which appear to be accessible only by removing the dome/surround, spider and tinsel leads and pulling the assembly out. The motor and frame are also glued together, however they can be pried apart. I didn't know all this and just pried mine apart as carefully as I could, breaking the screw mounts in the process. I cleaned the old fluid off and added some better stuff and glued the parts together again. It seems to work as well as the good one now and if I had to open another one I'd consider the same method as I couldn't see an easy way to access those screws.

There is a little bit more info in post #5 of my thread here: http://www.audiokarma.org/forums/showthread.php?t=598587

BadjerJim · Aug 30, 2014

Cool. Thanks!

Bill_Van · Jun 26, 2023

A400 said:
I have RS6001s and had this problem with one midrange, the other is still working well. I confirmed an issue with test tones prior to deciding to operate. Apart from the difference in sound the vibration felt by touching the driver when playing music was much weaker on the bad driver.

There are three screws holding the motor to the frame which appear to be accessible only by removing the dome/surround, spider and tinsel leads and pulling the assembly out. The motor and frame are also glued together, however they can be pried apart. I didn't know all this and just pried mine apart as carefully as I could, breaking the screw mounts in the process. I cleaned the old fluid off and added some better stuff and glued the parts together again. It seems to work as well as the good one now and if I had to open another one I'd consider the same method as I couldn't see an easy way to access those screws.

There is a little bit more info in post #5 of my thread here: http://www.audiokarma.org/forums/showthread.php?t=598587

Reviving the thread.... how did you remove the dome and the spider without destroying them?

A400 · Jun 28, 2023

Bill_Van said:
Reviving the thread.... how did you remove the dome and the spider without destroying them?

As I wrote above and shown in the photo in the thread I linked I somewhat carefully removed the magnet from the frame, rather than removing the dome/cone and spider. I couldn’t see a better way to do it at the time.

Bill_Van · Jun 28, 2023

Thanks!

Infinity Polysherite Mid - Ferro-fluid?

BadjerJim

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A400

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BadjerJim

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Bill_Van

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A400

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Bill_Van

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