Replacing drivers in Sonus Faber speakers..anyone?

@daveyf wrote:

in the past, I resorted to using a mild silicone oil on rubber surrounds. I won’t do that again, as I noticed it tends to actually increase the demise of the rubber, due to an increase in the drying out cycle. 

I suspect there must be variations in the silicone oils available on the market that, likely in conjunction with particular rubber surrounds, can lead to the problem you describe.

However my experience with silicone oils (and those I know who use it) haven’t led to any issues. Previously, some 25 years ago and a ~decade ahead, I owned a pair of speakers from Danish manufacturer Peak Consult, and they used Audio Technology woofer/mids with polypropylene cones and rubber surrounds. These were treated with the stuff from cans locally called "vinyl makeup" (i.e.: a silicone oil solution), and it was the man himself behind the speakers, Mr. Per Kristoffersen, that recommended named treatment. All of his speakers used Audio Technology woofer/mids. A friend of mine still owns his InCognito’s that are 25 years old and that have been treated with vinyl makeup occasionally, and they’re still in great shape.

So, my take is it must depend on the particulars one way or the other and whether named treatment is successful or not. With your experience I can understand why you would refrain from using it. If the rubber surrounds on your GH’s still feel supple and soft (some butyl rubber variants last many decades), I wouldn’t worry, not least if you kept them out of direct sunlight and have fairly stable atmospherics. 

@phusis  it makes some sense to treat the rubber surrounds with a silicone oil, which is why I used to do it with my old Hales speakers that utilized Dynaudio mid drivers. I then did the same thing with a pair of Kef’s that I owned briefly, and the results were not good. I think it might be a solution with the GH drivers, but I am not inclined to risk it since the drivers appear to be fine…so far.

@daveyf 

If you're serious about the need to replace the drivers I'd be making contacts and buying replacements now. Every day that goes by it's less likely you'll find replacements of older, custom made drivers if they exist at all. Companies and distributors come an go or are sold all the time.  One thing that happens when a business gets sold before or after a sale is old inventory is disposed of.  Shelves full of NOS drivers that have little turnover are of little use to new owners that are concerned about making money on inventory that turns over on a regular basis. 

The best chance you'll ever have to locate replacements is today. 

Nah, just get new speakers.

You must ascertain the condition of the fastening points in the cabinet. Can it survive a driver r/r? Will it take threaded inserts? Can you mount the new drivers rigid and plumb?