[julianburke]

You are talking about a well and overdone subject about a rotary converter near the theater. Rotary converters are no longer used but are still in place. Although I have seen no evidence of that effect, this is an extreme circumstance that would bother anything.

We were talking about the earth's magnetic field, and NOT extreme man made circumstances like that.

As far as the Letterman Theater is concerned, the threat was never much of a problem:

"When the Ed Sullivan Theater was built next door to IRT Substation #13, Lobenstein said CBS made a deal with the IRT; since the extreme radio-frequency energy emitted by the station would make the network’s cameras behave oddly, the IRT agreed to shut down the substation each Sunday evening while Sullivan’s show was broadcast. After CBS moved David Letterman’s show there in 1993, the network inquired about the possibility of doing the same thing for Letterman’s nightly tapings. The MTA balked that time around, since shutting down a working substation each weekday in the middle of the evening rush hour wouldn’t have worked as well. CBS wound up surrounding the entire Letterman stage in a Faraday cage of quarter-inch plate steel to block the RF emissions. The rotary converters were finally de-energized in December 1999, when they were replaced by new solid-state rectifiers, which are much smaller, quieter, cooler, and easier to maintain."