Wednesday, January 15, 2014

Recording Terminology Pet Peeve: "Low Cut" or "High Pass" Filter?

You ever notice how the world of recording can get really dogmatic about an idea? How very often you’ll see someone doing something, but they can’t explain why they’re doing it that way? The answer I most often get in situations like that is usually along the lines of “that’s just the way you’re supposed to do that”, but without any explanation as to why it works. It’s the recording equivalent of doing a rain dance. When it works it’s great…

Even what we CALL a tool can fall into this dogma trap. 

Take for instance one of my biggest recording pet peeves. There’s a hardware process we use to help remove ultra-low frequency noise from our recording chain. It can sometimes be found on our interface, sometimes on a mixer or preamp, or even directly on the mic itself. It’s a godsend for reducing a little rumbling or buzzing in our audio.

What is this magic process called? 

Well, about 50% of the time it’s called a “High Pass Filter”, which makes just a little bit more than absolutely zero sense to me. I like being precise with my direction and communication, and I like knowing what tools are called, that there are standards. Sometimes this is a “High Pass” other times it’s a “Low Cut”, and you can almost always count on the fact that no matter which term you pick, your engineer will use the other term, and will feel compelled to correct you on it. I’ve just about dislocated my eyeballs from rolling them so frequently with every helpful correction I’ve received.

More to the point, the term “High Pass” is just obnoxiously imprecise. What does the tool do? It reduces low frequency sound, often starting the roll off around 80Hz. Even more aggressive filters rarely creep above 160Hz, still nice and deep. The mid range and high end are both left intact and largely unaffected. Is it a “Mid and High Pass Filter”? No. Just a “High Pass”, which makes it sound like the filter should be working on the high end of the EQ, that the filter is affecting the upper bands, which it absolutely is NOT doing.

Why are we naming filters based on what the filter ISN’T doing? 

It’s just so passive aggressive. If I were to walk into a studio and have the following exchange with an engineer:
Me: Hey Mr. Engineer, what part of the EQ are you cutting there? 
Engineer: Not the highs! 
I’d probably never work with that studio ever again. Communication is already hard enough. We’d despise working with someone who defined everything they do by what they’re NOT doing. Even the lunch order would be miserable.
Me: Hey Mr. Engineer, what do you want for lunch today? 
Engineer: Not tapioca pudding! 
So, as we approach a new year, with all new possibilities, it’s time. Time to let go of this backwards way of defining what happens when we flip the switch on our mixers and mics.

It’s time for the Low Cut filter to reign supreme.


  1. I think of it as a doorway, high pass lets the signal through, you don't call a doorway 'wall with a space in it', even tho the only effect it has on people is if they hit the wall,

    huh, but you can call it what you want

  2. I just immediately thought of the Scottish song that goes "Ye'll take the high road and I'll take the low road...." The high literally goes around low lying stuff. At least, that's how I'm going to remember what the heck this means.

    an' I'll be in Scotland a'fore ye!