Choosing music you know well is the best place to start when compiling tracks for a reference CD. If you like AC/DC’s Back in Black all the better: The album’s title song is a staple for many engineers.
In last month’s column [“Mix Tricks,” September 2013], we talked about the primary tools for mixing. I finished up with the suggestion that you spend as much time as possible critically listening to music through your studio-monitor system. It’s really the only way to set the stage for creating great-sounding, transportable mixes.
What exactly should you listen to? The short answer is as many different things as possible, especially music that you know extremely well. This brings us to another mixing tool we need to discuss: the reference CD. Reference CDs are used by many engineers—in both live and studio situations—as well as acousticians, to evaluate and quickly “learn” a room and its monitor or speaker system. The idea here is to compile a compact disc with a variety of carefully chosen tracks that will reveal various aspects of the monitors and the room. For example, AC/DC’s “Back in Black” is a staple track for many live-sound engineers. If an engineer can make a room sound great with that track, it’s likely a rock band is also going to sound great through the system.
I’ve had the same reference CD for over a decade now. I don’t necessarily listen to the tracks all the way through, but I will dial up certain sections or passages that will tell me what I need to know. The following are a sampling of the songs on my disc and some brief notes about what I listen for. These songs were selected as tools, not because I like them (though I do like them). The variety of musical styles and instruments represented here is noteworthy, because even if you mix one style of music exclusively, you still need to hear a lot of different things to really learn a room.
Mixing with Headphones
I’m often asked if you can mix with headphones. You can, but it isn’t easy. The problem is that headphones—while they may sound wonderful—do not create the same type of response in our ears that speakers do. This is mainly because of the proximity of the drivers in the headphones to our eardrums. It’s very hard to judge the relative levels of signals in headphones—especially ambience and effects like reverb. Likewise, stereo imaging and placement isn’t as easy with headphones because each ear is isolated and receives a discrete signal.
With speakers, however, the sound coming from two speakers makes its way into both ears. This is important for how we judge where a sound is coming from and how far away it is. Headphones also often have “hyped response,” which means the bass or treble is boosted to compensate for the small headphone drivers and proximity to the ears.
All said, it’s not impossible to mix with headphones, especially if you have a really good pair. It’s just more difficult and requires that you listen to the mix on real speakers now and then for a perspective check. On the other hand, having a good set of headphones when mixing is essential for micro-scrutinizing tracks, listening for distortion or small clicks/pops, and so on. It’s also a great idea to listen through your mixes on headphones and inexpensive earbuds, simply because so much music today is consumed using these devices.
“Gaslighting Abbie,” Steely Dan. This track sounds remarkably consistent no matter where I hear it, so if something sounds off, there’s a problem. This is a good track to start off a listening session.
“Lotus Eaters,” Los Angeles Guitar Quartet. With four classical guitars going at once, I’m listening for separation between instruments and stereo imaging to determine if I can precisely pinpoint the location of each guitar in the stereo field.
“I Love You,” Sarah McLachlan. This cut starts with a nearly subsonic synth-bass part and it instantly tells me about the bass response of the speakers and room. When an electric bass enters later in the track, I listen for the independence and clarity of the two simultaneous bass parts.
“North Dakota,” Lyle Lovett. This track has outstanding dynamics and depth, along with long and smooth reverb tails. I’ll ask myself if the room and monitors are accurately reproducing them.
“Living Dead Girl,” Rob Zombie. This is one of the densest mixes ever. If you can hear all the worms and squiggles within the mass of guitars, you’ve got good clarity. I also listen for presence and impact from this powerful track.
“Big Bug Shuffle,” Douglas, Barenberg, Meyer. With an upright bass, Dobro, and steel-string acoustic guitar, this track covers a broad frequency range, wide dynamics, and excellent imaging. On a good system, you can clearly hear—though way in the background—someone tapping his foot along in time.
“Line ’Em Up,” James Taylor. This is another masterful recording with big low-end and a lot of depth that is remarkably consistent across playback systems.
“Where Will I Be,” Emmylou Harris. This is an atmospheric recording with a very deep bass drum, so some real bottom-end horsepower is required to bring it out. There’s also a lot happening with plenty of reverb and delay. With this track, I want to make sure everything is audible against that big bottom.
“Open Your Eyes,” Staind. Big, bottom-y metal punch. I like metal, but it’s often challenging for me to find recordings that truly sound good. Why is that?
I also include tracks by Rage Against the Machine, Diana Krall, AC/DC (yes, “Back in Black”), Toy Matinee, Flim & the BB’s, an orchestral piece, a big-band track, and more.
These are a few of the tracks that I use. You might put together an entirely different disc. One key point to keep in mind: Use full-bandwidth, unencoded recordings such as WAV files that are taken straight off a source CD. We want maximum fidelity for our references, not a degraded source like MP3s or some other compressed file format.
There is much more to say about reference discs, but we’re out of room. Next time we’ll continue talking about how to listen to your system and how to learn your room using a reference CD and other music sources.