Taming high end is a notoriously tricky endeavor. Especially for those with significant experience, it’s a region in the frequency spectrum that manages to get out of control quickly. Too much top and your mix will burn ears. Too little and it will sound lifeless.
To address the challenge of mixing high frequencies, here are five tips for taming treble:
Mixing high end is easier when there is already a relative balance between the rest of the frequency spectrum, i.e. lows and mids. Before you make adjustments, listen for issues between kick drums, bass, and other low-mid elements to avoid making decisions that harm the mix. You will set yourself up for an unnecessary challenge if you try to tame highs when lows and mids are suffering.
For example, if the bottom is boomy, you might boost the top excessively to compete. Conversely, a thin low end will make your highs seem overloaded in comparison, and to return to a perception of balance, you might needlessly reduce gain.
Checking these areas will give you a more accurate reading of your mix and help you determine what needs to be done to get the highs proportional to everything else. It could be that you need to add a whole new instrument part, but the solution could also be as simple as opening up a filter.
So how do you know if a mix is balanced? Like most music production exercises, your ears should be your guide. But if you don’t trust your ears yet or have less-than-ideal studio acoustics, iZotope’s Tonal Balance Control will provide you a visual representation of the frequency distribution in your mix. In real-time, it will map your current session against a reference target to reveal where there is too much (or not enough) of a specific frequency band for a big picture view of mix issues.
There are a handful of common issues with high frequencies that can be fixed with EQ:
Fix 1: If you can hear too much top (and Tonal Balance Control confirms it) try a cut around 3–8 kHz. Alternatively, a slight low-end boost will produce the psychoacoustic effect of dulling high frequencies, even if they haven’t been attenuated.
Fix 2: If high end is persistently dull, a gentle shelf from 10–15 kHz will open up the mix for air. Be sure to exercise caution when applying these boosts to individual tracks and submixes including high frequency-rich content. Cymbals, hi-hats, and bright synths will become brittle and painful to listen to when pushed too far up.
Fix 3: If lead vocals, guitars, or synths are having trouble cutting through the mix, or you simply want to emphasize them for specific sections, a small boost in the 3–5 kHz region can help. Again, be selective in your use of this EQ boost. If multiple elements get the same bump, you’ll end up with a harsh mix.
Our ears a very sensitive to EQ boosts—even a single dB of gain can sound like “too much” on certain instruments. In these cases, it can be more effective to dial in a cut before the desired frequency band, which will make it sound as if you’ve turned up the highs.
If you want to get sparkling high end but prefer not to boost with EQ, slap on a saturation plug-in, harmonic exciter, or full-on distortion effect (such as Vintage Tape, Exciter and Trash 2, respectively) instead. These processors add harmonics to signals for an “enhancing” effect that is a little warmer (think tape machines and tube amps) than your standard digital EQ.
Adding harmonics also adds gain, so both of these plug-ins include a Gain Match feature that ensures whenever you bypass the effect, the original version is at the same perceived loudness level as the processed one. Since we have a preference for louder over quieter, this allows for more accurate judgment over sound quality when switching between the two versions.
Note—too much harmonic excitement can damage a mix by making it overly bright, so err on the side of caution when adjusting effect levels.
Reducing sibilance—those really sharp high frequency sounds—is an often necessary part of mixing. Dialogue and vocals with the letters S, F, X, and T are one of the more common sources of sibilance. Some performers are naturally sibilant when they speak or sing, but microphone choice and processing can contribute to this issue as well. Kept in a mix, these hissing sounds are quite distracting, so we created the De-ess module in RX 7 to easily whisk them away.
Keep in mind, de-essers are not just for vocals. Many instruments have a harshness to them as well, and a de-esser is a great way to tame specific bands where the issue persists, specifically for guitars, percussion, and even synths. It natural to reach for an EQ to tame sibilance on instruments, but a cut at 5 kHz or so might also grab the part of the signal you want to keep, making a de-esser a smoother, more surgical solution. Here’s how on guitars:
The mix is a battleground for frequency space, and it gets particularly messy in the upper range. If you have an arrangement with constant crashes, clanging percussion, and “in your face” vocals and synths, you need to make some decisions about which elements should be dominant and what needs to get reeled back with filtering.
Darker elements often appear further back in the mix when contrasted with bright ones, so a subtle low pass on secondary elements will not only free up space in the mix, but help to establish a sense of depth.
Every song calls for a different approach to mixing high end. The five tips provided in this article will give you enough guidance to tackle the most persistent high-frequency issues for a mix that feels balanced without comprising excitement.