Twelve Common Mixing Mistakes

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

           

No Sparkle and Bottom

Of course, sometimes EQ boost is needed to make a mix sound great. You can generally get away with boosting extreme bass and high frequencies more than you can boosting midrange frequencies. That's because the human ear is less sensitive to phase shift at the extremes of the audible spectrum. Even after boosting the bass and highs a bit, you may find that your mix still doesn't have the huge bottom end and sparkly highs you yearn to hear.

Again, the reason may be that you're listening at too loud a level while making EQ decisions. That's a problem because the human ear is subject to the Fletcher-Munson effect. In plain English, this means the ear is much less sensitive to bass and high frequencies when listening at low volumes than at high volumes. (Many consumer stereos have a Bass Loudness button to compensate for this reduced sensitivity to bass frequencies at low listening levels.) Ear fatigue aside, if you adjust EQ to taste while monitoring at loud levels, your mix might not sound sparkly and thunderous enough once the playback level is turned down.

Knowing this (and to preserve my hearing), I spend most of my mixdown time with my monitors set no louder than a spirited two-way conversation, and I'll often set them a lot lower. If I can get the mix to scintillate and thunder while listening at that low level, it is going to absolutely rock when it's cranked. Also working in my favor, my high-frequency sensitivity won't be trashed by sustained listening at loud levels, helping me retain an accurate perspective of spectral balance. That said, I will crank my control room monitors for about 20 seconds or so every hour when I'm mixing to confirm that the bottom and top ends still sound great and that I haven't taken any EQ boost too far.

One other point: if you compress tracks such as bass-guitar and cymbals post-EQ, the compression will at least partially negate the effects of any EQ boost on those tracks. Try placing the compressors before any EQ boost to get more sparkle and boom.

Large Swings in Spectral Balance

Sometimes the timbre of specific elements of a mix (or of the whole enchilada) is a moving target. For example, the electric bass or acoustic guitar might sound boomy on some phrases yet be well balanced everywhere else in the song. The lead singer might have a shrill high register that bites your head off during the choruses, whereas the lower register sounds perfect during the verses. Or the entire mix might get edgy when, for instance, a bunch of midrange instruments pile on for one section of the song.

FIG. 2: Electric guitars sound awesome when processed with the PSP VintageWarmer 2 split-band compressor plug-in.

In these cases, static EQ settings won't sound good throughout the song. One worthy solution, albeit a time-consuming one, is to ride the EQ on individual tracks as needed. But a quicker and sometimes more elegant-sounding fix is to slap a split-band (aka multiband) compressor on the unruly tracks — or even on the entire mix. A split-band compressor divides the audio spectrum into multiple, adjustable frequency bands so that each can be compressed independently. Examples of outstanding split-band compressors include the Tube Tech SMC-2BM (a high-end analog unit) and the Waves C4 Multiband Parametric Processor, Waves Linear Phase Multiband, and PSP VintageWarmer 2 plug-ins (see Fig. 2).

Adjust the bandwidth of one or more of the split-band compressor's bands to include only the frequencies that exhibit large swings in level (for instance, bass frequencies that sometimes get too loud and make the mix boomy), and bypass the other bands. Then set each active band's threshold to be at or slightly below the level where the offending frequencies begin to annoy. Adjust each active band's ratio, attack, and release controls to taste to limit how much (if at all) the unruly frequencies can bloom above the thresholds you've set. With the proper settings, a split-band compressor will automatically nip large swings in spectral balance in the bud. (For more in-depth information on how to use split-band compressors, see “Let's Split!” in the January 2004 issue of EM, available online at www.emusician.com.)

Insufficient Detail

When a mix is lacking in detail, boosting high-frequency EQ is often the wrong approach. When that just creates a glassy mix without solving the problem, try cutting the upper-bass and low-midrange frequencies instead. Too much energy in these bands can create a blanket of mud that obscures a mix's underlying transients, so try cutting between 200 and 500 Hz before boosting highs. Just be sure not to overdo it, or else you'll end up with a thin mix and too much detail.

FIG. 3: The SPL Transient Designer can be used to increase the amplitude of the attack portion of drum tracks to create a punchier mix. The 2-channel TD2 is shown here.

Another thing to consider on a cloudy-sounding mix is whether sustained sounds such as string or synth pads are too loud. By simply lowering some or all of the tracks that exhibit minimal transients and loud average levels (sustain), percussive elements will more readily punch through. The end result will be a mix with plenty of detail that nevertheless retains its warmth because of minimal use of EQ.

Not Enough Punch

A mix lacking detail will also often lack punch, or transient elements married to tightly focused bass-frequency content. When a mix's spectral balance is already great, it can be a mistake to boost both bass and high frequencies to achieve more punch. The added highs might just make the mix sound glassy, whereas the extra bass boost could make it boomy.

FIG. 4: The Waves TransX Wide plug-in, part of the company’s Transform bundle, is set up here to deliver extra punch to a kick drum track.

Instead, use a dynamics processor to emphasize the attack portion of the low-frequency elements from which you want more punch (for example, trap drums and electric bass guitar). A solid-state, VCA-based compressor set to relatively slow attack and fast release times (start with 60 ms for each) will often do the trick.

The SPL Transient Designer, available in both 2- and 4-channel models, is an outstanding solution for increasing punch on individual tracks (see Fig. 3). This amazing analog processor uses an envelope follower to change the amplitude of the attack and release portions of an audio signal. With the twist of a single knob, the Transient Designer can greatly enhance the beater slap of a kick drum or the crack of a snare drum, and it can make a bass guitar track pop like balloons.

For reshaping transients inside the box, I often turn to the Waves TransX Wide plug-in, which is part of the Transform bundle (see Fig. 4). It offers much greater control over the attack portion of sounds than the Transient Designer but gives you no control over the release phase. TransX Wide is a surefire ticket to slammin' drum tracks.

Too Much Compression

These days, many mixes are so overcompressed that they become irritating and fatiguing to listen to after only one or two minutes. Overcompression is like a plague contaminating our industry. Make no mistake — I love stereo-bus compression, and I like my mixes loud, but there's a big difference between pumped-up, exciting dynamics and just plain annoying noise and distortion.

The old saw about using your ears when determining how far to push mix-bus compression is all well and good, but I have a more practical suggestion: watch the crest factor on your stereo-bus meters. The crest factor is essentially the difference between peak and average levels, and keeping tabs on it is a good reality check against what ears addicted to volume might otherwise be pushing to accomplish.

Spend time listening to your favorite records — particularly those that have dynamics you'd like to emulate in your mixes — patched through the 2-track return of your mixing console or DAW, and keep a close eye on the meters. (Make sure that the meters are peak reading and set to prefader listen, and that all processing is disabled.) Note how much the meters rise above average levels during transient peaks throughout various sections of each song. Then shoot for roughly the same crest factor in your mixes. You can learn a lot by being a good meter reader.

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