Sounds like they're looking for some kind of high-pass filter. Something that would "brick-wall" cut off any sound below (and including) 60hz.

I agree, though... 60hz has nothing to do with Air-Conditioning. Maybe in this case "A/C" = "Alternating Current." But, why would he want to turn off the power?

This guy is a relatively established director/producer and I don't want to come off ignorant cause he just hired me for an upcoming shoot. So I just wanted to check with you guys to see if you knew of some kind of noise reduction that works in real-time yet. I could see it as certainly being possible (sample the sound as one would in Noise Reduction 2.0 and tell that software not to let it pass thru in real time). I mean if they can correct pitch in real time why wouldn't it work?
Anyway, maybe someone will come along and enlighten us before I have to tell the guy I've never heard of such a thing...or perhaps he's confused.
Thanks guys,
Randy

Some factory floor offices are near high voltage 60Hz equipment, may be this is what he is talking about. Real balanced audio would be key for this, and avoiding dynamic microphones would also be a good idea (they have difficult-to-shield coils that can pick up all kinds of junk).
Next step would be to activate the 100Hz rolloff that many professional microphones have.

He is probably talking about an inline 60Hz notch filter.

This is a small box or cylinder with connectors at both ends. That would be the last resort, although if the field is that strong you really have to worry about video camera picture hum too.

Better go there and test beforehand.

Next step would be to activate the 100Hz rolloff that many professional microphones have.
Aha...that must be what he's talking about! I'll ask him now that I may have a clue what he might mean.
Thanks,
Randy

This is also called a "low-cut filter"

Here's Mackie explaining how it works on their mixers.


Jay Rose gave this advice to someone whose mixer used low-cut filters.

My mixer has Low Cut Filters: 140 100. What recommended settings?
100 is probably good for normal dialog, 140 if you're getting a lot of wind noise.

Basic rolloff in mics or desks isn't the best way to tackle this.
The rolloff is way to gentle (12dB/octave typically) and the problem isn't just the mains fundamental frequency, you'll almost certainly get harmonics at 120Hz and 180Hz adn beyond.
Best approach I've found is to look at a small section of 'silence' in SF using the spectrum analyser. Invariably I'll have peaks at 50Hz, 100Hz and 150Hz (I'm in a PAL land). I then use a paragraphic Eg to creat very sharp notches at those frequencies and problem is largely solves.
But even this isn't perfect. The narrowest I can set those filters is 1/3 octave and they introduce a small amount of gain at the corner frequency and probably phase shift to boot as they're emulating analogue filters. One day I'll get some real forensic plugs that are pure digital filters with very sharp rolloff and phase coherance.
This technique though I find better than using NR2, if you know what you've got to kill to get rid of a noise plain Eq can be quicker and less likely to cause problems elsewhere.
Bob.

Just in case anyone is interested, this is what the guy was talking about. I can't imagine using it myself (I use XLR for one thing) but...
Randy

Sorry but it looks like a pretty el cheapo effort, it's got x levels of bass rolloff and they don't tell you what they are nor if it alters the frequency or the attentuation or slope. Things like that I think I'd leave out of the line, you can do the same in post and then you have controls with numbers on them and if you get it wrong it's really easy to change.
And it's another thing to go faulty and kill your audio for good.
Bob.

I totally agree Bobaloo.
Randy