My 1050 just developed a really bad low frequency hum. Any ideas how to track down and eliminate?
It did disappear when I switched off my sub, but I'm assuming that just because of the normal crossover cutoff. Maybe it's the sub?

Now when you say it just developed a hum, did you add anything new? Are you using cable tv? That is usually the culprit for the hum. Although the sub is the component producing the hum, it is most likely not the cause of the hum. This is more likely than not a ground loop issue, for which you will need to try a ground loop isolator or cheater plug thingy. I don't have any links handy, but if you do a search, you may find more info, since i think this issue comes up every so often.

It is extremely interesting that you mention the cable TV. I was listening to the system at night and everything was fine. The next morning our cable repair tech came to investigate a pixilation problem. He fixed it by installing some sort of signal amplifier. I was not home while he did that. Later when I turned the system on, I hd the hum. Since the cable guy never touched my system I did not want to jump at the idea that what he did caused the problem.

The cable signal does go through the 1050 though.

Is there a filter that can get rid of the noise?

There are multiple ways to solve this problem. Do a search on ground loop, either here, or on www.hometheaterforum.com and you should be able to find more info.

I came across several such links this week (putting together the Saloon links ), including the following:

Fixing Cable-TV Hum in Audio Systems
RF attenuators, filters, and DC blockers

The first link would be a good place to start.

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Gonk