Major Contradiction, Can you replace foam surrounds with Rubber Surrounds on Speakers ???


Hi Guys, I have a major conundrum to decide, and need the experts in the community to help. I have the Wilson Watt Puppy 6's and have 4 woofers that need re-foaming.

 Here's the issue, First, according to Wilson, I had called 2x(at different times) and asked to speak with a speaker engineer, Both times the knowledgeable staff member that answered the phone said that wasn't possible, but would relay any message to them on the spot and get back with me while I hold. My question was: Can you replace the foam surrounds on the Wilson speakers with Rubber Surrounds . After waiting on hold for about 5 minuets, he said "yes, you can",

I Then proceeded to call the well regarded Miller Sound in PA, who is recognized to one of the best in the Industry to do the replacing of speaker surrounds. I proceeded to ask the same question to him, and he said, "No, & that it would change the sound of the speaker and to only redo them using foam surrounds to preserve its original sound quality" . I see no other supporting evidence one way or the other on the net. What do you folks say and please elaborate one way or the other to help me justify my decision. Thank you, Rich
audiofan1
Surrounds will not appreciably change the sound if they're of the same...or nearly the same geometry and compliance. Foam and butyl are both pretty lossy when it comes to the cone termination. The moving mass difference will likely be not enough to audibly change the sound. When measuring for moving mass half the weight of the spider and surround are subtracted to get to net moving mass.
On big woofers at low frequencies, like in the Watt Puppy, the surround does not appreciably impact the cone movement. Push them to a higher frequency and they will, ditto for mid-woofs at higher frequencies, and mids across most of their frequency range. 
You got some GREAT advise from a professional rebuilder, why are you asking. If you want to go with BR surrounds , go for it. It will change the sound, plain and simple.. It will be what you turn it into.. There is a place for BR, fabric, or silicone surrounds. I have drivers with silks and wire from 1934. They work perfect..

New foams with treatment will last 30 years if you rotate the driver 180 every 2 years or so..

BR 50 years

Fabric, 100 years

Silicone forever... :-)

Regards
You got some GREAT advise from a professional rebuilder, why are you asking.


You got some generic advice from a rebuilder who probably did not consider how the product was used in application, in your specific model of speaker.  Great rebuilder. I have used them myself a few times. Does not change the validity of the answer. 


When you asked Wilson, did you communicate which model of speakers you were trying to repair and what drivers in that speaker, or was it a totally generic question?  If you asked specifically, then the answer has a lot more merit than generic.


Whatever you change to, it is going to change the sound from home they sound today. Period. 
I'm an old speaker guy and can tell you that ANY speaker recone is a guess in a sense.  If you have ever re-coned many speakers, you may notice that you get one surround and it is thin and wimpy,  you get another and it is thick and stiff.  Anytime you change the mechanical ease or difficulty that allows the driver to move,  you change QMS.  So the trick would be to try to mimic how stiff that original surround is.  The likely hood is,  If you have a sealed box woofer that you could get away without much noticeable difference using a butyl surround, but be aware,  YES, the woofer spec will change when changing from a foam to rubber surround.  If you do change it, make sure that you re spec the woofer, the port tuning may need to be tweaked.  Again,  if it is sealed, the difference should be minor.  Good Luck,  Tim