Wednesday, September 15, 2010

That Vocal Sound, Part 2 - Compression

So you've successfully notched out the "nasties" from the vocal. Now, as far as the harmonic balance of the vocal sound, you're feeling pretty good. Now, let's listen to the dynamics. Are certain syllables or words popping out? Are the front ends (attacks) of words or lines louder than the rest? Is the volume and presence of the vocal consistent throughout each section? If there are problems in these areas, your vocal might benefit from some compression.

Keep in mind, if the song calls for a very natural vocal sound --say, if it's a very open-sounding acoustic track, or a soft ballad-- then we might choose to avoid compression entirely and simply control the dynamics by riding or automating the fader. Compression almost invariably changes the sound of a vocal, making it smaller and tighter... (On a good day, 'focused'!) Sometimes, if the vocal's already sounding good, this does more harm than good. Listen to the song, and listen to the vocal carefully. Ask yourself, what does it need?

Compression serves many purposes, but in vocal processing, usually we ask a compressor to even out the volume of words or phrases. That purpose informs how we'll set the compressor. Specifically, if we want the compressor to react to a word that's too loud, we'll set the attack relatively fast so the compressor can react quickly to the word, and set the release quick enough to get out of the way. In this scenario, we'd set the compression threshold to be just above the peak (or RMS) level of the vocals that are at the correct level. Then, when the loud word comes along, the compressor grabs it quickly, reduces it quickly with a medium to high ratio (say, 6:1), and then releases quickly as the vocal settles down.

More commonly, we want the compressor to not simply react to specific words, but to keep the performance present and clearly audible in a busy mix.  This is how we achieve that coveted "in your face" vocal sound. To accomplish this, we set the threshold lower, so the compressor is working throughout the entire section. Attack will still be relatively fast (do experiment to see what sounds good!), as will release, but these settings will depend on the compression curves of the device or plugin you're using, and how much compression you're applying. Common ratios for this application are 4:1 to 8:1, and you might be applying 3-12dB of gain reduction. Adjust your makeup gain accordingly.

Things to listen for: If your attack is too slow, the beginnings of verses or phrases may pop out, as the relaxed compressor "grabs" at the front end of the signal. This can also be a sign that you need to lower your threshold more. A release that is too fast will bring out the ambience of the room or booth the singer was in, and potentially make the vocal spitty or ess-heavy. A release that is too slow will make the vocal sound somewhat farther back in the mix, reducing the presence that we're using the compressor to achieve. Also, if the threshold is too low, and we're applying too much compression, the effect can be that of abrasiveness or fatigue, as the push and pull of the words and spaces gets too flattened out by the compression and becomes unnatural. Tinker with a compressor on a vocal until you can hear these effects. Listen closely. If you can't hear it... Keep at it! It takes time!

Every compressors will react to a given source differently, depending on the compression curves and attack/release characteristics. (If these terms are alien to you, don't worry! I'll do a chapter specifically on these nuances of compressors. For the time being, just embrace that different compressors can behave a bit differently.) When you're setting a compressor, once you get some serviceable settings on the compressor, you'll want to "feel out" where the sweet spot is by listening carefully to the source while adjusting the parameters (I focus on threshold and release). Ideally, you're listening for where the action of the compressor is keeping the source controlled, but also making it more full and exciting. Good hardware compressors will also impart a tone or color to the sound depending on gain staging (i.e. how hard you're driving the compressor's input and output stages). Even plugin compressors will exhibit a sweet spot in the compression behavior if you listen and adjust the parameters carefully!

How does the compressed vocal sound in the mix? Is it "up front" and present? Is the sound and performance "focused"? If so, you're on the right track!

You may discover at this stage that the vocal needs additional EQ. Perhaps the compression has brought out a nasty frequency that you didn't realize was there before, or perhaps the overall tone now seems too dark. You have the option of adjusting the pre-compression EQ to compensate, or adding another EQ post-compressor (which I do frequently).

"2 EQs on a vocal?!? That's insanity!!!" you say. Not really. Remember, our first EQ was really just cleanup. The tracking engineer should have done this for us, but we won't hold it against him. Besides, now that the sound is more focused and present (thanks to the compression), we're better able to adjust the balance of the vocal tone to get it to sit in the mix. This may involve boosting some midrange (say, in the 1-3kHz range) to add some presence and bite, or shelving down some low end (perhaps 300Hz and below) to get the vocal to sit with the arrangement. You may hear a new "nasty" that you want to notch out. Perhaps the vocal needs some top-end brightness that a bell or shelf at 6-8kHz can bring out. Again, you will have to listen, listen, listen to the vocal track, the rest of the mix, and perhaps some reference mixes to discern what is needed for a particular track.

Next up: Vocal Effects!

Tuesday, September 14, 2010

That Vocal Sound

The human voice is a fascinating instrument. The physics of how sound resonates in the larynx and vocal cords and projects through the throat and mouth, combined with the resonances of the chest and sinuses, creates a staggeringly rich and complex signal. And every last one of these instruments is different from the next.

Now, factor in the dimensions and reflectivity of the room or booth the singer is tracked in, the sonic imprint of the microphone, the singer's positioning on the mic and the microphones polar response --nope, we're not done yet. Don't forget the fingerprint of the mic preamplifier, the behavior of any vocal compression, the tone of the AD converters or tape media... No two vocal sounds are going to be the same.

For sake of discussion, let's say there are two starting points when mixing vocals. The first is, "the recorded vocal already sounds good." This means the tracking engineer (which might be you!) did his job well, and you're trying to preserve a good thing. In this scenario, you're in "Do No Harm" mode, and will use far less processing.

The second starting point is, "The vocal doesn't sound good (yet)"... and therefore needs some help. In this case, the complex system described above introduced some undesirable components to the vocal signal that we want to clean up. Hopefully, we can do some quick surgery, and then find ourselves back in "Sounds Good" mode.

Personally, if I'm trying to clean up a vocal, I think about removing the unwanted artifacts (resonances) from the signal. Generally, I'll use several narrow cuts with a parametric EQ to accomplish this. Perhaps skewer out some ~220-250Hz to remove proximity effect, cut something in the 300-500Hz range to defeat room/booth tone buildup, perhaps notch out something around 700-900Hz that might be sinus or head resonance. This is clean-up, so I'll do this prior to any additional processing (compression, effects, etc). As always, it's essential to use your ears to figure out what's needed.

A quick note on subtractive EQing: A great technique for finding troublesome frequencies to notch out with a parametric EQ is to select a narrow Q (bandwidth), boost heavily, and sweep the frequency of the EQ band to find the ugly component of the sound. Then, keeping the narrow Q, cut that frequency to taste (could be a 3-12dB cut). You may then wish to adjust the Q as needed to make sure you're scooping out as much or as little as desired. You'll discover there's a trade-off between the depth of the cut and the bandwidth. Experiment to see which suits the material better.

 Vocal tracks are frequently compressed to tape. And heavy subractive EQing can rob a compressed signal of fullness and life. (Listen for this; it has a sound.) So be careful what and how much you're cutting, and always A/B your EQ'd track to the original by flipping the EQ in & out of bypass. Did you make it sound better?

If we've succeeded in EQing out some of the "nasties" from the vocal, we can determine if additional processing is needed. If the mix is dense, or we want the vocal to be very up front and "in your face", some compression may help. We'll talk about this shortly...

Monday, September 13, 2010

Learning To Hear

While much of the content here will be devoted to very concrete tools and techniques, I will also frequently delve into the philosophy and mindset behind mixing. After all, mixing is fundamentally a mental process, a gradual accumulation of a million tiny decisions. It would be impossible (or at least very difficult!) to describe each and every one of these, so I think it's essential to instill a mindset that equips the aspiring mixer to fight this battle... Or rather, to flow through the process of making these decisions.

I find mixing to be very meditative. When you're in the right headspace, and you have the vision, the mix will tell you what needs to be done. It really becomes a matter of listening. Learning to listen, however, is a truly challenging process.

The human sense of hearing is taken wildly for granted. In our daily lives, most of us pay far less attention to what we hear than we do to what we see, for instance. Less of our conscious mind is directed there, and more takes place automatically. When people speak, we instantly focus on the language. When we hear a sound, we instantly link it to an object (such as a car, or a dog, or a freshly opened can of beer) without much additional analysis.

Our brains, however, gather much more information from what we hear than we are aware. Your unconscious is keenly aware of tone of voice and inflection when someone speaks, for example. This informs your emotional response to what's being said, whether you're aware of it or not. The sound of a car passing on the street is automatically localized (meaning, you can tell where the car is), the Doppler shift in pitch tells you something about it's trajectory (is it coming towards you, or passing nearby), and your brain instantly gives you a sense of distance based on the volume and ambience (how much time to do you have to jump out of the way!).

So there's a vast amount of information that is available in what we hear that we usually don't pay attention to. With practice, however, you can train your attention and expand your understanding of what you're hearing. This is true when listening to the amazingly complex variety of sounds out in the world, as well as much simpler things, like how a compressor is affecting the snare track.  A great mixer utilizes this understanding to paint the picture between the speakers. So ultimately, your ability to mix is determined by your ability to listen... to hear and process this information that you normally don't pay attention to.

By now, the reason for my choice of titles for this blog ("Zen Mixing") should be clear!


Greetings and Salutations! My name is Eric Peterson, and I'm a mix and mastering engineer based in Los Angeles, CA. Like many of you, I savor the experience of losing myself in a sonic landscape. I love the world of imagination and emotion that is created by a fantastic mix... It's like another dimension, an alternate reality.

I've spent the last 12 years diligently honing my craft, mixing and remixing projects for countless clients, looking over the shoulders of some of the best in the business, consuming every available bit of information... Quite simply, I've been unrelentingly passionate about learning the tools and techniques of this art, and the journey to reach the level of skill I now enjoy has been one of the most profound and edifying experiences of my life. My intention is to use this blog to aid others in their journey.

Much of this material will also be compiled into a book, as well as several online training modules, both of which will offer more depth to the topics, as well as sonic examples to help practice and ingrain the concepts presented. To that end, I welcome any and all suggestions and feedback. Please help me understand what I can do to help you aspiring mixers out there!