EPI 100V Ferrofluid Tweeters

[TechFall]

Long time lurker, first time poster. I grabbed a set of EPI 100Vs for a steal of 25$. The grills are darn near perfect (one is missing the EPI wave logo). The veneer is in great condition, save for some sliding scratches on the bottom. I pulled the covers and the woofers foam surrounds disappeared in the wind (have replacements on order). The cones and voice coil look perfect. The magnets on both tweeters fell off (typical, considering what I’ve read on here). I’ve looked pretty extensively on AK for the answers to the following question:

1. When I replace the Ferrofluid, what viscosity is needed, and where would I get this specific viscosity?

I did put a call into H. Powell over at Human Speakers, but he hasn’t gotten back yet. Any help would be appreciated. Thanks!

 

[Guido57]

Huw is a one man operation as far as I know. His response time varies because of this.

 

[nerdorama]

You sure there is ferrofluid in these tweeters? I've never heard that.
John

 

[TechFall]

I’m pretty sure. I feel like I read that somewhere...I’ll need to check my sources. And, when the magnets popped off, there was a dark, fluid-like substance at the bottom of the magnet and around the ring of the underside of the tweeter.

 

[Guido57]

Grease in the early versions (think Masonite), fluid in the latter ones.

 

[RTally]

The later EPI tweeters were ferroflluid cooled. The early masonite tweeters were not. See https://www.humanspeakers.com/e/epi100.htm

As for buying different viscosity FF for individual use, I don't think that is possible. Buy it by the barrel and you can get it to the specs you want, but if you are not a driver manufacturer, you won't know the specs that you need. I doubt that there is much variation if FF used by the different driver manufacturers because the way FF works is the same for every driver. The biggest variation is going to be the size (diameter difference) and volume of the VC gap.

I believe your only option is to buy the generic FF sold by Parts Express and similar companies.
https://www.parts-express.com/ferrofluid-100ul-general-purpose-for-1-diameter-vc--340-540

 

[Guido57]

I got the grease information for the early tweeters from what I consider a respectable source, though not Huw. As my Masonite tweeters remain firmly in one piece I don't feel tempted to open them up to check.

 

[TechFall]

Thanks for the advice Tally. I was able to speak with a local speaker repair shop, and it was he who advised (warned??) me that, "You need to be careful, there's different types of viscosity." Lol...I believe that he was trying to get my business when I inquired about buying ferro. I've seen it there on Parts Express and I should have figured that when there was only one type of fluid available, that it did not matter the viscosity.

On a side note, with everything I've read on here about these speakers, I can wait to hook them up!