Currently Being ModeratedSep 8, 2013 9:27 AM (in response to Bonferroni)
Possible Solution for under $2.00: Plug the display into one of those ground eliminating plugs that allow you to plug grounded cords into old style two prong receptacles.
I took my display to the Apple Store. They could not reproduce the sound, so they were unable to do anything to fix it. While the Thunderbolt display was on vacation at the Apple Store, I thought more about what MAD SCI described as the possible source of the problem ["THAT MEANs that all these devices are now connected. Problem being is that the audio is not protected from ground noise…"]. The fact that the display worked fine at the Apple Store, lead me to think the problem was with the electricity in my office, since it is in a historic building in an old downtown area. I suspect my electricity may have ground noise since I have to plug everything (Wi-Fi modems, phone modem, external network drives, copier, printer, lamps, etc.) into the same circuit.
When I got my display back I decided to try plugging the display's power cord into one of those little plugs that converts a three prong into a 2 prong, by eliminating the ground prong. I plugged the display into the ground-eliminating plug, then into the surge protector. While I confess it has only been a few days that the display has been functioning under these conditions, there is no hiss sound. Last time I thought I found a solution, I performed experiments to recreate the hiss and it never went away; so this time I have decided to be superstitious rather than scientific. So you should take this report as an anecdote only.
Additionally, I do not recommend this solution, because eliminating the ground may cause problems. [As described by MAD SCI: "It is only protection against lightening really. So if you wonder why apple has done this and not fixed it yet, it’s more political than you think…."] With this in mind, I believe there is a risk the described fix could turn your display into a useless piece of junk, if there was a power surge from a lightening strike that was not eliminated by the expensive surge protector it is probably plugged into. Of course, since my noise was so loud, the display was already a useless piece of junk (until I eliminated the hiss with this "kludgy" fix), I figure I have nothing to loose.
Currently Being ModeratedSep 12, 2013 6:31 AM (in response to PatQuinnPhD)
Not yet, it stopped making the noise and I got really busy with school. It sounds like it will fix the problem if it comes back though. I'll post an update if anything changes.
Currently Being ModeratedDec 6, 2013 4:13 AM (in response to Bonferroni)
I have the same issue with my TB Display. It does improve a lot when the display is Daisy Chained to a LaCie Raid TB HD. http://www.lacie.com/products/range.htm?id=10061. Sometimes the noise come back but I would say it does impeove to a 70% less noise.