Alright boys, after months of not mixing and on fresh ears..

What sources benefit from LPF? I usually LPF e.gtrs and bass. What else?

You mean Low pass/ high cut , Low pass lets the stuff under the corner freq pass through and blocks those above!
I know it's confusing!
I'm going to say both are essential but monitoring that lets you hear both ends is even more essential !

Oops ericn beat me to it! Yes high pass and high cut can be a mind fuck.

LF and HF tend to impress us fast.

I think cutting on both ends can make sense.
Depend's on the sound I have in mind, depends on the stile of music too.

One reason why I don't like modern mixes is the tendency for HF content like crazy.

What worked in Mix A often does not work in Mix B.
I take general statements with a grain of salt, for inspiration.

Yeah - definitely. Listen to the latest Keith Urban record. Sounds really good to me. But you don't hear much of anything over 12khz

With my ears you sure don't!

I think I sometimes confuse clear with bright. Confuse is maybe not the right word, but I want clear, wide, deep mixes. Sometimes they just end up bright. I think because I fear dull.

Can somebody speak to the cutting of high frequencies in the range of human hearing, but the boosting of "air" stuff (well) above 20 KHz?

Cheers,
Geoff

You been holdin' out!!

Fascinating subject, and one that seems often missed - especially by younger engineers (not saying you are young CCM...)  Everyone (ok, ok...most everyone) knows about and is committed to using HPF's, but few venture into LPF territory.  Basically, IMO, it's critical to getting a mix to sound "analog" if that's what you're after.

One technique - if you have ears you trust, and a good monitoring environment, take a 6dB per octave LPFilter, instantiate it or insert it into a track, start out with the corner freq around 20k +, and slowly start sweeping it down until you hear it "doing something" to the signal.  Then stop.  Move it back up just a tad (for instance, if you could hear it start to cut @ 11k, move it back up to 12k or so) - then go on to the next track and repeat all the way thru your mix.

Do a global bypass of all filters on your mix and listen to the difference - the top end will smooth out, there will be room for tracks that NEED the HF, and overall it will sound better when you remove energy that's way up there that you can't hear.  That's the first step.

Once you master that and feel comfortable killing all your unwanted HF's, start taking creative license and go FURTHER than what you can hear.  Try a 12dB per octave filter.  Get rid of un-neede HF sizzle on the bass, kick drum, hats or anything else you don't feel needs it - for creative reasons.  You'll open up even MORE room up there for the elements that DO need it.  Uncongesting the HF in a digital mix is critical, and I'd argue that for digital mixing, is just as important as utilizing good HPF engineering.

Glad you're having the epiphany.  It's counter intuitive to how we hear stuff "solo'd" and is scary until you get used to it.  Another way to accomplish the same thing is do a bunch of analog stuff before, during or after you hit your DAW.  Works.  Getting rid of un-needed HF rocks the mix!

The problem is that the words are misleading because typically, HPF are applied at lower frequencies and LPF are applied at higher frequencies. I.e. The terms describe keeping what you want to hear, but when we use them we usually are thinking in terms of what we don't want to hear. They should have called them High Cut Frequencies, or High Shelving Frequencies. I wonder why didn't they? What were the earliest applications that might explain that?)

Anyway, you may have to think about it when you communicate it, but it's not really a problem when you're actually using it because when you LP, you usually grab the HF knobs without thinking, and of course for those of us who mostly live ITB, there's a visual there making it clear what's going on.

The Fabfilter EQ has a solo button where you can hear what you're rolling off. Pretty interesting to hear what above 10kHz really sounds like.

That sounds like a cool feature.  Makes it easier to hear what you're loosing.

On another note, I'm kind of amped up this AM.  Too freaked out to mix or use any LPF's.....  Had to kill a decent size Mojave Green who was on the back porch this morning.  First one I've seen here since moving - and easily within striking distance of the back door.  I thought these things were supposed to stay in the desert.  LOL  Unfortunately, no.  They are up here at 5500 ft altitude.  Dog found it before the wife did thank God.  Gets your adrenaline going.....