Will sun exposure damage my speakers?

I have a window next to one of my newly purchased JM Lab Electra 926s and since I like their look without the grill, I was wondering if I was hardening my cone surrounds or not. They are fiberglass "W" cones so I suppose they are ok but I don't know for sure. Has anyone looked into this before? Thanks! Arthur
While ordinary window glass absorbs a fair amount of uv radiation, enough gets through to be of concern. Many plastic resins are not uv stable, so the amount of exposure should be considered. Are you getting direct sun or indirect light? If only a little direct sun hits them during the day, I wouldn't worry too much. Too much sun exposure can also bleach wood veneers over a period of time also.
Yes, it will. It will cause premature failure of foam surrounds and fade parts of the cabinets that are exposed to the light.

Having said that, i'm in the same situation with one of my systems. As such, i treat the cabinets with Lemon oil, which keeps them from drying up and helps retain their "rich" wood finish, and i rotate the speakers. This keeps the "fade" relatively consistent between the two, yet does nothing for the other side of the cabinet that isn't exposed to light. Sean
Yes, absolutely! During the course of the year my REVEL sub gets quite some sunshine and I cover it with a towel during that time and days. Whatever rubber is used for the cones: it doesn't like the sun at all.
Good luck!

Direct sunlight will "cook" foam and the plastic resins in the
fiberglass cones causing them to become embrittled which
ultimately leads to failure.

I'd keep the speakers out of direct sunlight.

Dr. Gregory Greenman
If the position allows too much light and you don't have options or glass tint is not of your liking, you might consider adding a fabric cover to your speakers to preserve them. In other words if you leave to work early in the morning and get back early in the evening, your speakers will stay all day long getting the light exposure without you enjoying their look. The covers can be made of decor color matching fabric, perhaps your S. O. stays all day long in the house she can put the covers to lessen the visual obstrusive boxes in your den or living, so maybe you can have a win/win scenario and improve WAF. My 2 cents.
That is what I thought. I usually put the grills back on on sunny days. I guess I will continue to do so! Thanks again

Sun rays ultimately change all that is in their path.
With speakers it will bleach the cabinets, dry the wood, and also, affect the drivers, (surrounds) if exposed too much.
Sort of like the white rat tests. "If a rat consumes 12.5 Million gallons of X it causes cancer". Hell if he consumes anything in THAT quantity it will kill him.
Moderation, combined with some UV filtering will help.
Get yourself some liquid latex.  Foam surrounds that are failing absorb it like a sponge.  A few coats works wonders and adds years to the drivers. 
Yes keep them out of the Sun. As an engineer of 20 years in the polymer field you should keep your speakers out of direct sunlight.
We may have found a thread on which the vast majority of audiogon participants agree! Success!  ;) 

UV is not good in the long term for most modern surrounds, cones and dome materials.
Get some fabric covers for the speakers to protect it from direct sunlight. It’s not only with driver surrounds and other parts of the speaker as the wood finish will be affected as well. You may get uneven shades on the woodwork as the surfaces exposed to direct sunlight will get dark through time. Imagine a nice year round tan on human skin.

Damn, just noticed this thread was posted 17 years ago. I wonder who resurrected this thread..

What about the sun on black lacquer finish like on JL audio fathom subs and revel ultima series speakers?

The sun could only potentially hit the back and sides of the speakers, the fronts have the grill and face into the room, and the sun comes from behind so the grilles and drivers are not in any direct sun.

i do cover with sheets, but I wonder how much UV gets right thru sheets?

(I remember reading that UV goes right thru T-shirts)

Anyonr know of a sheet or cover made to filter UV fully?