Twelve Common Mixing Mistakes

Jul 1, 2007 12:00 PM, By Michael Cooper

As a mastering engineer, I hear a lot of mixes from other studios. Some are great, some are not. But what is striking to me is that the mixes that need help usually suffer from many of the same problems. The good news is that these shortcomings can all be avoided or corrected by using a few simple techniques.

In this article, I will describe 12 common problems with wayward mixes and discuss how to solve them. If your mixes are routinely restrained by a lack of punch, clarity, and detail; if your productions are held hostage by unruly dynamics and spectral imbalances; or if your results don't sound as wide and deep as the mondo tracks created by your competition, read on for some liberating pointers. I'll address each problem and its solution individually, beginning at rock bottom.

Boomy or Thin-Sounding Mix

The most common problem I hear with mixes is uneven levels throughout the range of bass frequencies. This can present itself as either a thin-sounding mix or a boomy one. Some mixes sound alternately thin and boomy in different sections of the song.

The main culprit behind a skewed bottom end is mixing in a room that has not been properly treated with acoustic products to help tighten up impulse response and attenuate room modes. (Room modes, aka standing waves, are narrow peaks and dips in frequency response; they are especially problematic in the bass range.) These acoustic problems might lead you to, for example, unnecessarily boost certain bass frequencies to compensate for a thin-sounding mix when, in fact, the mix already has a perfectly balanced bottom end, though the room's uneven bass response at the mix position is telling you otherwise.

In truth, even rooms that have had thousands of dollars poured into their acoustic makeovers usually have some persistent problems with uneven bass response (although the inaccuracies are usually dramatically reduced in number and severity with proper treatment). Typically, one or two prominent room modes remain at the mix position, making it difficult to properly assess the mix's bass content in these narrow bands.

In most control rooms, there is at least one spot where specific room modes and other bass-response anomalies that compromise monitoring at the mix position are much weaker or even completely tame. While this alternate bass-reference spot might have other problems and be less accurate overall compared with the mix position, it gives you another reference for bass balance in the narrow bands you can't hear properly at the mix position.

How can you tell where the alternate bass-reference spot is? First, assuming that you have more than one pair of reference monitors, play a respected, full-bandwidth mix (usually one that a prominent record label has had mastered and released) through the speakers that have the deepest bass response (include a subwoofer if you use one). Choose this reference mix carefully: it should be one that has always sounded great on the bottom end no matter what sound system you've played it on.

Walk around your control room while the reference mix plays, listening to how the sound of the bottom end changes as different acoustic influences come in and out of play. Note the spot where the bass response sounds the most even at the specific bass frequencies that are out of whack (too weak or too strong) at your mix position — that spot should become a second place you go to check the bottom end when making bass-EQ decisions on your mixes.

Unfortunately, the alternate bass-reference spot is often inconveniently located with respect to the studio's mixer or DAW controller. For example, the place where the 40 to 45 Hz band is most accurate in my control room is about 3.5 feet in front of the back wall.

There is an easy solution: remote control. I always use my Frontier Design Group TranzPort wireless DAW controller (see Fig. 1) when checking a mix's extreme bottom end at the back of my control room. Using the TranzPort to remotely start and stop playback allows me to set my control room's monitoring level high enough that I can really hear those subterranean frequencies without blasting my ears at close range. I listen, evaluate the bottom end, stop playback, make the relevant EQ adjustments at my mixer, and repeat the process until the bass sounds great at both the mix position and the alternate bass-reference spot.

Edgy, Fatiguing Sound

Digital audio has a reputation for producing cold, brittle sound, but the problem often stems from poor engineering techniques. The most common factor contributing to an edgy, fatiguing mix is indiscriminate boosting of upper-midrange and high-frequency EQ on multiple tracks.

Here's a typical scenario: hours of mixing at high sound-pressure levels (SPLs) progressively compresses your ears' high-frequency sensitivity, and they become starved for the highs they're missing. To compensate, you boost the highs and upper mids to get back the detail and presence your tired ears can no longer hear clearly.

You check your mix the next morning after your hearing has recovered, and it's like fingernails on a blackboard. Rather than cut the offending frequencies, you opt to boost the bottom end to warm up the mix. Now you have phase shift (unless you've been consistently boosting using a linear-phase equalizer) and alternating peaks in response across virtually the entire spectrum, resulting in an overly edgy sound, not to mention decreased headroom.

The solution is to mix at lower SPLs and to cut offending frequencies whenever possible instead of boosting other frequencies to compensate. For instance, it usually sounds better to carve away bass frequencies than to hype the midrange EQ when trying to make a mix sound more present. As a general rule, using EQ to cut will sound better than using it to boost.

Other factors leading to a harsh-sounding mix include having too many midrange instruments in the arrangement or mixing them too up front with respect to the other elements. Know when to lower that bright organ pad to mellow things out a bit. Similarly, do you really need those 13 electric guitar overdubs? Consider muting some of the midrange elements that aren't essential and that only make the mix more fatiguing to listen to. Often the problem with a mix lies with the arrangement, and no amount of EQ will help.

Read more of this Electronic Musician article on how to correct common mixing mistakes

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