prevent hardening of speaker surrounds

I didn't think Armor All was classified as a solvent. I thought it was classified as a protectant. I have applied it to the rubber surrounds of two of my woofers, with terrific results. Most audiophiles do seem to not like Armor All, and much of that seems based on some bogus "tweak" a few yewars back, where it was tried on CD's (in the first place, that seems idiotic to me, since polycarbonate is not a pourous plastic). Anyway, if I can borrow my brother's digital camera again, I'll photo these woofers and e-mail the photos to you, if you're interested.

Well, if you are so interested in seeing this solubility table for Armor All, why aren't you asking them for it? Also, I did ask the speaker manufacturer specifically what their thoughts were before I applied Armor All, and they informed me that there would be no degradation of the rubber, and no interactions with the glue that holds the butyl rubber to the polypropylene cone. So you see, I took the only care that should have been taken, in my case. I didn't have to be a chemist to do it, either. BTW, the manufacturer is Dynaudio, and I feel that they might know a little bit more about speaker drivers (especially their own) than anyone who will ever contribute to this forum....and they have spoken.

To clarify something, here, I agree that the suspension of the speaker is of paramount importance. However, it's the rear suspension on cone speakers (the spider, a woven fabric) where the primary burden lies, with respect to how the cone behaves, since it is connected to the "balanced center" of the moving mass of the diaphragm. The front "surround" serves primarily to keep the cone centered during motion, and serves an extremely minute roll in the "suspending" of the diaphragm's mass. Therefore, changes in sonic performance over time are due to changes/wear in the spider, and not so much from the front surround. SUBARU ALLUDES TO THIS ABOVE.

As I state above, my feeling (and Dynaudio's) is that Armor All has no negative effect on a butyl rubber surround, or the glue that adheres it to the cone. I made no comment at all on its effect on a foam surround, and can only guess that it could very likely have a negative effect on foam. I also never said that the surround has "little effect on the sound", as you imply, I just said that the spider has vastly more. This assumes that the surround appears in good working order. If it is not, of course there will be a very noticeably degradation of performance. However, I never implied the contrary...If a surround can't keep the cone perfectly centered, of course there will be all sorts of bad things happening. Of course it is necessary to do whatever yopu feel is called for to maintain it, and I hope we all feel this way.

Interesting...however, I don't see the spider as ever "hardening", I see it simply wearing out; i.e., the fabric strands develop tiny fissures that grow and become more numerous with time and wear through usage. In effect, they become "threadbare". I also agree that the effects of gravity cannot be ignored.