"It's All About the Low End"...What Does That Even Mean?

It's all about the low end. When you get that right, everything else falls into place. I've said it again and again, but what does it mean exactly? Today we'll talk about what it means for the audience, for the system engineer, and for front-of-house and studio mix engineers. Plus a little guitar tone nugget in there at the end.

The full adage is “It's all about the low end, when you get that right, everything else falls into place.”

It was one of the first things that I learned from my very first audio mentor, Jason Cole. He was the sound and IT guy at my church when I was in high school and joined the worship team, and I was just starting to get interested in sound. Over the last 22 years of doing audio, the more I found this quote to be reliable and true. And the wisdom keeps unfolding in the trueness of this statement. So today I thought I'd take some time to walk you through some of the applications of, “it's all about the low end.” So let's get started.

Hey, if you're new here, my name's James and I help you make stuff sound good. So if you want to make stuff sound better, this is the place to be! 

Let's Talk About How Masking Works

The first place where it's all about the low end is for the listener. And I'm going to describe a phenomenon to you called masking. Now, the first part of masking is really obvious and simple. It states that loud sounds cover up quiet sounds. And now you can leave this blog post knowing something new! No, of course you already knew that something loud covers up something quiet. But the second part of masking is the interesting phenomenon that low frequencies will cover up high frequencies. So when you have two frequencies where one is lower than the other one, and they're about the same perceived amplitude, the low frequency will make the high frequency appear quieter. This can work to our benefit or it can work to our detriment.

So here's what I mean: if something's muffled and you've got a live vocal mic and somebody's all up on the vocal mic (like they should be), and it's muffled, you won't hear the intelligibility from the presence region in the 2-5 kHz range that helps to make it feel close and understandable. If you pull those little frequencies down a pinch, suddenly the higher frequencies become more apparent. They're getting less covered up by the lower frequencies. In audio engineering, it's not just about energy, it's about intelligibility. So this is an important place where it's all about the low end.

But while intelligibility is one of those necessary requirements, people say live events sound good because of the low end. So if you've got a solid, appropriate low end as part of your mix, people are going to say, “Hey, this sounds good!” or “This sounds impressive!”. On the flip side, if your sound system or your mix doesn't have enough low end, that actually feels louder and harsher to people without being any higher energy level. So you could be exposing them to the same amount of noise, but if it has a higher low-frequency proportion, it might not feel quite as loud.

You can try this the next time you're mixing: push up a recording and make it sound nice and big and full on your sound system. Then, turn on the high-pass filter and roll that up until it starts to sound thin. If you've got the option, hit bypass on that high-pass filter, and suddenly it doesn't sound so loud and harsh. You didn't change any intensity of those upper mid frequencies that are going to hurt a little bit more, but having those lower frequencies balances it out and tells your ear “It's okay, this is a good place to be”.

Balancing Low End in a Live Setting

Next up, let's talk about system engineers or live sound design. Now for this, “It's all about the low end” is really important because it's really tricky to get low frequencies right in a large room with a lot of different speakers. Low frequencies behave quite strangely compared to upper or middle frequencies. Because the wavelengths of these low frequencies are so large, there come to be issues with summation between two different subs arriving at the same point at different times. And even with reflections and boundaries, lots of things go into the factors of making low end, even in a large space.

Another place that can cause issues with low frequencies is room resonances. Sometimes the actual physical structure will resonate with these lower frequencies causing some to hang on longer than others and giving the impression that they're actually louder when they're just hanging on longer.

Another factor for system engineers is making sure that there's the appropriate amount of low end coming onto the stage. Some performers really like to feel it when they're on stage. That's how they know that they're connecting. But it can be out of proportion and too much sometimes. So we don't always want to throw a bunch of low end back on the stage. Sometimes we want to direct that energy more forward than backward. Knowing when and how to do that is critical, and that again, is why it's all about the low end.

Getting Instrument and Vocal Levels Right

For the mix engineer behind the console, it's all about the low end. And here's where from your kick drum, you can set the level of the snare, the toms, and the overheads. From the bass guitar, you can set the level of your other guitars, your keyboards, and then finally the vocals. So if you get the relationship right on the low end, then everything else can fall into place.

I talked a little bit earlier about vocal EQ and similar to an overall mix, the balance of the vocals’ low frequencies can make it either feel too harsh, if you don't have enough and you've pulled out too much low end, or on the flip side, if there's too much low end, then we're going to run into intelligibility issues. Now, vocals in particular are really tricky in that people's tone and their voice sounds different when they're singing low and quiet in a verse or high and loud when they're in a chorus. That's why a lot of times I'll even ride the low shelf up and down on the vocal EQ to make sure that the vocal is warm and present right where it needs to be in both parts of those songs.

Now, we've talked about the kick and the bass already, but for the rest of the instruments, using your high-pass filter to filter out all unnecessary low end can really make a big difference in cleaning up your mix. And you can do it with one knob, so it happens pretty fast. One mixing trick that I like to use is to set my high-pass filter right about at the lowest note that that instrument is going to produce. Then if I've got a bass guitar, along with electric guitars or acoustic guitars, I'll ride that high-pass filter up an additional octave if needed. So for an acoustic guitar, I might set my high-pass filter at 80Hz because the lowest note on a standard tune guitar is 82Hz. If I have a bass that's playing most of the time when that guitar is playing, I'm going to go ahead and ride that high-pass filter up to maybe 150 or 160Hz. Then with the bass and the guitars together, the bass has more room for its overtones to live in that lower end of where the guitar would've been. And your ear kind of melds all those together into one big thing that sounds clean and full. So for the mix engineer, it's all about the low end. When you get that right, everything else falls into place.

Achieving Low End Balance in Your Studio Space

Now, if you've got a hi-fi system or a home studio or someplace where you're trying to mix music in more of a studio environment, it can be really tricky to get the low end right. And again, it's all about the low end. When you get that right, everything else falls into place. In smaller rooms, and by smaller I mean like not your big live sound room, we tend to have a lot of weird stuff going on with the low frequencies. A low frequency will come out of your speaker, bounce off one wall, and then cancel itself out coming back. Other times that wave will bounce and then combine with itself to make it louder than when it came out of the speaker in the first place. These are called standing waves or cancellation. Even without room resonances and the walls shaking as we talked about a little while ago, that can cause some really weird things to happen in the frequency response of your speakers.

So when you're trying to get your kick and your bass relationship just right on the low end and then all these weird things are happening in your room, it's like you're driving with a blindfold on. You really can't tell with your ears what's going on with those low frequencies. Maybe you've made this mistake before where you try to mix something and automate the EQ on the bass to get every note to stand out just right, but then somewhere else you listen to it and all you hear is that one note that you couldn't hear in your studio. Low end translation is one of the hardest parts of studio mixing. So when you can get your monitoring environment to be as flat and low as possible, that can go a long way toward making it a lot easier to mix. That way you can make creative decisions, not “Is this going to work somewhere else?” decisions. And pro tip, one place where the low end is always really even is in your car, because all that low end can escape, it goes straight out and doesn't bounce around. So if you need to take your phone to your car and check your mix there.

One Final Tip for Guitar Players

Now this last one's a bonus because I'm usually talking to sound techs, but if you're an electric guitar player, It's all about the low end as well. When we overdrive an electric guitar into a guitar amp, it can start to sound flabby. That's why we have guitar pedals that will boost a signal or distort it internally, and it includes a high-pass filter to get rid of the flabby feeling.

I'm a big fan of Brian Wampler and the way that he describes guitar tone circuits. Basically, he's just putting a high-pass filter before the drive so that it doesn't get out of proportion when we clip and distort this signal. That's essentially what a treble booster is doing into an amp. We're taking a mild high-pass filter and cleaning up the guitar's low end before it goes into overdrive.

I hope you've enjoyed this discussion about why it's all about the low end. When you get that right, everything else falls into place.

Remember: it's all about the low end, avoid the sound tech solo, and nobody leaves humming the kick drum.