Whats the use of high-cut?

[The Scum]

Keep in mind that air itself attenuates high frequencies - the farther away something is, the darker it becomes. We aren't always listening to things from the same perspective that we mic them.

Here's a calculator that can demonstrate the effect...you'll find it's much more prevalent at high frequencies.
http://www.sengpielaudio.com/calculator-air.htm

So we can simulate distance with a filter, when pulling the mic back and adding gain isn't practical.

My science of music professor, Mark Ballora, always cited a study that was done where they played a recording to test subjects that had all of its 20 kHz content in tact, and then they played the recording again with all of the 20+ kHz data cut off. The test subjects were able to identify which one had more data even though all of the sound was above the human hearing level.

There's part of me that's skeptical about such anecdotal evidence. I'd want to know more about the test protocol, and how the filtering was implemented and tested. Did they carefully verify that there were truly no changes in the 20 to 20,000 Hz range? Designing a filter that's a hard stop at 20 KHz is not a trivial matter...and one of the common side effects is that the frequency response of the passband becomes bumpy. (and audible) Is there any chance that the filtering process either changed the audible band somehow, or that there were other effects related to the wider bandwidth material (intermodulation distortion, perhaps?).

If wider bandwidth source material were obviously superior, 96 or 192 KHz sampling would be a foregone conclusion, and we'd all have DVD-A or HDCD players by now.

which instruments do you think absolutely need that "air"

Absolutely? None of them.

12 string guitar on Tuesdays.

Cymbals on Thursday evenings.

And more air on everything as a long night of mixing becomes even longer.

You might solo tracks through a spectrum analyzer. You'll find that there are lots of sources without much going on above 5 or 10 KHz.

[Scodiddly]

You might solo tracks through a spectrum analyzer. You'll find that there are lots of sources without much going on above 5 or 10 KHz.

I was showing off one of my piano mic prototypes at a studio open house engineer club thingy a few years ago. With the open grand near the drumset we got plenty of bleed... then one of the guys low-passed down to 7 or 8 kHz. We could all hear the difference, of course. But it was surprising how little it really changed the sound of the piano while killing off a lot of bleed.

[Marc Alan Goodman]

My science of music professor, Mark Ballora, always cited a study that was done where they played a recording to test subjects that had all of its 20 kHz content in tact, and then they played the recording again with all of the 20+ kHz data cut off. The test subjects were able to identify which one had more data even though all of the sound was above the human hearing level.

If I farted on the snare drum the test subjects would be able to identify which track had the fart on it. That doesn't mean it makes for a better recording.

Some top end you need, some you don't. The top end can get cluttered the same way the bottom can, or the middle. Sometimes the right tool is a gentle shelf, sometimes you just want to chop it the hell off. Plus it's really good for cleaning up things that were tracked poorly and have a lot of garbage noise happening in ranges other than the captured instrument's.

[GooberNumber9]

Most of the EQ I do at any frequency is to make room for something that I feel is more important at that frequency. I usually low pass almost everything but vocals and cymbals so there is more room up top to help the vocals stay in front. I've even low passed overheads a little bit to free up some of that "air" space for vocals. Usually I do that same thing that I do with high pass: I engage it and sweep it down from the top (up from the bottom) until i can just barely hear it obviously, and then back it off a bit.