Info needed from Speakerlab expert

I know that they used ferrolfluid in their horn drivers but wasn’t sure if they used it in their cone midrange drivers. And what years they used it. These are 4s not sure what vintage. I wasn’t looking forward to replacing it in them.
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I'm sure there's no ferro-fluid in that driver.
I had a pair of the 0.1's for awhile. Same driver I'm pretty sure.
The CTS woofers were always the best part of the Speakerlab designs. Yours appears to be in good shape.

Dave.