Mixing Techniques with DAW Software
By Anderton |
Check out the latest advances and techniques for mixing with DAWs
by Craig Anderton
The best mics, recording techniques, and players don’t guarantee great results unless they’re accompanied by a great mix. But the face of mixing has changed dramatically with the introduction of the DAW, both for better and worse. Better, because you don’t need to spend $250,000 for a huge mixer with console automation, but worse because we’ve sacrificed hands-on control and transparent workflow.
Or have we? Today’s DAWs have multiple options—from track icons to color-coding to configurable mixers—that help overcome the limitations of displaying tons of tracks on a computer monitor. While this can’t replace the one-function/one-control design of analog gear, some tasks (such as grouping and automation) are now actually easier to do than they were back in the days when analog ruled the world.
As to hands-on control, controller-related products keep expanding and offering more possibilities, from standard control surfaces with motorized faders, to FireWire or USB mixers, to pressing keyboard workstations (such as Yamaha’s Motif XS/XF series or Korg’s M3 or Kronos) into service as controllers. These all help re-create “the analog experience.”
Although we’ll touch a bit on gear in this article, it’s only to illustrate particular points—the main point of interest here is techniques, not features, and how those techniques are implemented in various DAWs. And speaking of DAWs, if you’ve held off on upgrading your DAW of choice, now might be the time to reconsider. As DAW feature sets mature, more companies focus their efforts on workflow and efficiency. While these kinds of updates may not seem compelling when looking over specs on a web site, in practice they can make the recording and mixing process more enjoyable and streamlined. And isn’t that what we all want in the studio?
So pull up those faders, dim the lights, and let’s get started (click on any image to enlarge).
The typical mixer has several places where you can set levels; proper gain-staging makes sure that levels are set properly to avoid either distortion (levels too high) or excessive noise (levels too low).
There’s some confusion about gain-staging, because the way it works in hardware and software differs. With hardware, you’re always dealing with a fixed, physical amount of headroom and dynamic range, which must be respected. Modern virtual mixers (with 32-bit floating point resolution and above) have almost unlimited dynamic range in the mixer channels themselves—you can go “into the red” yet never hear distortion. However, at some point the virtual world meets the physical world, and is again subject to hardware limitations.
Gain-stage working backward from the output; you need to make sure that the output level doesn’t overload the physical audio interface. I also treat -6 to -10dB output peaks as “0.” Leave some headroom to allow for inter-sample distortion (Fig. 1) and also, it seems converters like to have a little “breathing room.”
Fig. 1: SSL’s X-ISM metering measures inter-sample distortion, and is available as a free download from solidstatelogic.com.
Remember, these levels can—and usually will—be brought up during the mastering process anyway. Then, set individual channel levels so that the mixed output’s peaks don’t exceed that -6 to -10dB range.
One of the most useful features of virtual mixers is that you can configure them to show only what’s needed for the task at hand, thus reducing screen clutter (Fig. 2).
Fig. 2: This collage outlines in red the toolbars that show/hide various mixer elements (left Steinberg Cubase 5, middle Cakewalk Sonar 8.5, and right Ableton Live 8).
Mixing often happens in stages: First you adjust levels, then EQ, then stereo placement, aux busing, etc. Granted, you’ll go back and forth as you tweak sounds—for example, changing EQ might affect levels—but if you save particular mixer configurations, you can recall them as needed. Here are some examples of how to use the configurable mixer feature when mixing.
- The meter bridge. This is more applicable to tracking than mixing, but is definitely worth a mention. If you hide everything except meters (and narrow the mixer channel strips, if possible), then you essentially have a meter bridge. As software mixers often do not adjust incoming levels from an interface when recording (typically, the interface provides an applet for that task), you can leave the “meter bridge” up on the screen to monitor incoming levels along with previously-recorded tracks.
- Hiding non-essentials. Visual distractions work against mixing; some people even turn off their monitors, using only a control surface, so they can concentrate on listening. While you might not want to go to that extreme, when mixing you probably don’t need to see I/O setups, and once the EQ settings are nailed, you probably won’t need those either. You may want to adjust aux bus sends during the course of a mix, but that task can be relegated to automation, letting you hide buses as well.
- Channel arrangement. With giant hardware mixers, it was common to re-patch tape channel outs to logical groupings on the mixer, so that all the drum faders would be adjacent to each other; ditto vocals, guitars, etc. With virtual mixers, you can usually do this just by dragging the channels around: Take that final percussion overdub you added on track 26, and move it next to the drums. Move the harmony vocals so they’re sitting next to the lead vocal, and re-arrange the rhythm tracks so they flow logically. And while you’re at it, think about having a more or less standardized arrangement in the future—for example starting off with drums on the lowest-numbered tracks, then bass, then rhythm guitars and keyboards, and finally moving on to lead parts and “ear candy” overdubs. The less you need to think about where to find what you want, the better.
- Track icons. When I first saw these on GarageBand, I thought the concept was silly—who needs cute little pictures of guitars, drums, etc.? But I loaded track icons once when I wanted to make an article screen shot look more interesting, and have been using them ever since. The minute or two it takes to locate and load the icons pays off in terms of parsing tracks rapidly (Fig. 3). Coupled with color-coding, you can jump to a track visually without having to read the channel name.
Fig. 3: Acoustica’s Mixcraft 5 is one of several programs that offers track icons to make quick, visual identification of DAW tracks.
- Color coding. Similarly, color-coding tracks can be tremendously helpful if done consistently. I go by the spectrum mnemonic: Roy G. Biv (red, orange, yellow, green, blue, indigo, violet). Drums are red, bass orange, melodic rhythm parts yellow, vocals green, leads blue, percussion indigo, and effects violet. When you have a lot of tracks, color-coding makes it easy to scroll to the correct section of the mixer (if scrolling is necessary, which I try to avoid if possible).
WHY YOU NEED A DUAL MONITOR SETUP
If you’re not using two (or even three) monitors, you’ll kick yourself when you finally get an additional monitor and realize just how easy much easier DAW-based mixing can be—especially with configurable mixers. Dedicate the second monitor to the mixer window and the main monitor to showing tracks, virtual instrument GUIs, etc., or stretch the mixer over both monitors to emulate old-school hardware-style mixing.
Your graphics card will need to handle multiple monitors; most non-entry-level cards do these days, and some desktop and laptop computers have that capability “out of the box.” However, combining different monitor technologies can be problematic—for example, you might want to use an old 19” CRT monitor along with a new LCD monitor, only to find that the refresh rate has to be set to the lowest common frequency. If the LCD wants 60Hz, then you’re stuck with 60Hz (i.e., flicker city!) on the CRT. If possible, use matched monitors, or at least matching technology.
Several DAWs include channel strips with EQ and dynamics control (Fig. 4), or even more esoteric strips (e.g., a channel strip dedicated to drums or vocals).
Fig. 4: Cakewalk Sonar X1 (left) and Propellerhead Reason (right) have sophisticated channel strips with EQ, dynamics control, and with X1, saturation.
However, also note that third-party channel strips are available—see Fig. 5.
Fig. 5: Channel strips, clockwise from top: iZotope Alloy, Waves Renaissance Channel, Universal Audio Neve 88RS.
If there are certain settings you return to frequently (I’ve found particular settings that work well with my voice for narration, so I have a vocal channel strip narration preset), these can save time compared to inserting individual plug-ins. Although I often do make minor tweaks, it’s easier than starting from scratch.
Even if you don’t have specific channel strips, many DAWs let you create track presets that include particular plug-in configurations. For example, I made a “virtual guitar rack” track preset designed specifically for processing guitar with an amp sim, compression, EQ, and spring reverb.
There are three places to insert effects in a typical mixer:
- Channel inserts, where the effect processes only that channel
- Master inserts, where the processor affects the entire mix (e.g., overall limiting or EQ)
- Buses, where the processor affects anything feeding that bus
Proper busing can simplify the mixing process (Fig. 6), and make for a happier CPU.
Fig. 6: Logic Pro’s “Inspector” for individual channels shows not only the channel’s level on the left, but also, on the right you’ll see the parameters for whatever send you select (or the output bus).
In the days of hardware, busing was needed because unlike plug-ins, which you can instantiate until your CPU screams “no more,” a hardware processor could process only one signal path at a time. Therefore, to process multiple signals, you had to create a signal path that could mix together multiple signals—in other words, a bus that fed the processor.
The most common effects bus application is reverb, for two reasons. First, high-quality reverbs (particularly convolution types) generally uses a lot of CPU power, so you don’t want to open up multiple instances. Second, there’s an aesthetic issue. If you’re using reverb to give a feeling of music being in an acoustic space, it makes sense to have a single, common acoustic space. Increasing a channel’s reverb send places the sound more in the “back,” and less send places it more in the “front.”
A variation on this theme is to have two reverb buses and two reverbs, one for sustained instruments and one for percussive instruments. Use two instances of the same reverb, with very similar settings except for diffusion. This is because you generally want lots of diffusion with percussive sounds to avoid hearing discrete echoes, and less diffusion with sustained instruments (like vocals or lead guitar) so that the reverb isn’t too “thick,” thus muddying the sustained sound. You’ll still have the feeling of a unified acoustic space, but with the advantage of being able to decide how you want to process individual tracks.
Of course, effects buses aren’t good only for reverb. I sometimes put an effect with very light distortion in a bus, and feed in signals that need a little “crunch”—for example, adding a little grit to kick and bass can help them stand out more when playing the mix through speakers that lack bass response. Tempo-synched delay for dance music cuts also lends itself to busing, as you may want a similar rhythmic delay feel for multiple tracks.
Grouping is a way to let one fader control many faders, and there are two main ways of doing this. The classic example of old-school grouping is a drum set with multiple mics; once you nail the relative balance of the individual channels, you can send them to a bus, which allows raising and lowering the level of all mics with a single control. With this method, the individual fader levels don’t change.
The other option is not to use a bus, but assign all the faders to a group (Fig. 7).
Fig. 7: In PreSonus Studio One Pro, the top three tracks have been selected, and are about to be grouped so edits applied to one track apply to the other grouped tracks.
In this case, moving one fader causes all the other faders to follow. Furthermore, with virtual mixers it’s often possible to choose whether group fader levels move linearly or ratiometrically. With a linear change, moving one fader a certain number of dB raises or lowers all faders by the same number of dB. When using ratiometric changes, raising or lowering a fader’s level by a certain percentage raises or lowers all grouped fader levels by the same percentage, not by a specific number of dB. In almost all cases you’ll want to choose a ratiometric response.
Another use for grouping is to fight “level creep” where you raise the level of one track, then another, and then another, until you find the master is creeping up to zero or even exceeding it (see the section on Gain-Staging). Temporarily group all the faders ratiometrically, then bring them down (or up, if your level creep went in the opposite direction) until the output level is in the right range.
Yes, I know people mix with a mouse. But I highly recommend using a control surface not because I was raised with hardware mixers, but because a control surface is a “parallel interface”—you can control multiple aspects of your mix simultaneously—whereas a mouse is more like a serial interface, where you can control only one aspect of a mix at a time.
Furthermore, I prefer a mix to be a performance. You can add a lot more life to a mix by using faders not just to set static levels, but to add dynamic and rhythmic variations (i.e., moving faders subtly in time with the music) that impart life and motion to the mix. In any event, you have a lot of options when it comes to control surfaces (Fig. 8).
Fig. 8: A variety of hands-on controllers. Clockwise from upper left: Behringer BCF2000, Novation Nocturn, Avid MC Mix, and Frontier Design AlphaTrack.
One option is to use a control surface, dedicated to mixing functions, that produces control signals your DAW can interpret and understand. Typical models include the Avid Artist Series (formerly from Euphonix), Mackie Control, Cakewalk VS-700C, Behringer BCF2000, Alesis Master Control, etc. The more advanced models use motorized faders, which simplify the mixing process because you can overdub automation moves just by grabbing faders and punching in. If that option is too expensive, there are less costly alternatives, like the Frontier Design AlphaTrack, PreSonus Faderport, Cakewalk VS-20 for guitarists, and the like. These generally have fewer faders and options, but are still more tactile than using a mouse.
There’s yet another option that might work even better for you: An analog or digital mixer. I first got turned on this back in the (very) early days of DAWs, when I had a Panasonic DA7 digital mixer. It had great EQ and dynamics that often sounded better than what was built into DAWs, as well as motorized faders and decent hardware busing options. It also had two ADAT cards so I could run 16 digital audio channels into the mixer, and I used the Creamware SCOPE interface with two ADAT outs. So, I could assign tracks to the SCOPE ADAT outs, feed these into the DA7, and mix using the DA7. Syncing the motorized faders moves to the DAW allowed for automated mixes.
This had several advantages, starting with hands-on control. Also, by using the DA7’s internal effects, I not only had better sound quality but lightened the computer’s CPU load. And it was easier to interface hardware processors with the DA7 compared to interfacing them with a DAW (although most current DAWs make it easy to treat outboard hardware gear like plug-ins if your audio interface can dedicate I/O to the processors). Finally, the DA7 had a MIDI control layer, so it was even possible to control MIDI parameters in virtual instruments and effects plug-ins from the same control surface that was doing the mixing. While the DA7 is long gone, Yamaha offers the 02R96VCM and 02R96VCM digital mixers, which offer the same general advantages; also check out the StudioLive series from PreSonus.
However, that’s just one way to deal with deploying a control surface. You can use a high-quality analog mixer, or something like the Dangerous Music 2-BUS and D-BOX. Analog mixing has a somewhat different sonic character compared to digital mixing, although I wouldn’t go so far as to say one is inherently better than the other (it’s more like a Strat vs. Les Paul situation—different strokes for different folks). The main issue will be I/O limitations, because you have to get the audio out of the DAW and into the mixer. If you have 43 tracks and your interface has only 8 discrete outs—trouble. The workaround is to create stems by assigning related tracks (e.g. drums, background vocals, rhythm guitars, etc.) to buses, then sending the bus outputs to the interface. In some ways this is a fun way to mix, as you have a more limited set of controls and it’s harder to get “lost in the tracks.”
Today’s FireWire and USB 2.0 mixers (M-Audio, Alesis, Phonic, Mackie, etc.) can provide a best-of-both-worlds option. These are basically traditional mixers that can also act as DAW interfaces—and while recording, they have enough inputs to record a multi-miked drum set and several other instruments simultaneously. Similarly, when it’s time to mix you might have enough channels to mix each channel individually, or at least mix a combination of individual channels and stems.
Different programs call this concept by different names, but basically, it’s about being able to call up a particular configuration of windows with a simple keyboard shortcut or menu item (Fig. 9) so you can switch instantly among various views.
Fig. 9: Logic Pro 9’s Screensets get their own menu for quick recall and switching among views.
Like many of today’s DAW features (track icons, color-coding, configuring mixers, and the like) it requires some time and thought to create a useful collection of screen sets, so some people don’t bother. But this initial time investment is well worth it, because you’ll save far more time in the future. Think of how often you’ve needed to leave a mixer view to do a quick edit in the track or arrange view: You resize, move windows, change window sizes, make your changes, then resize and move all over again to get back to where you were. It’s so much simpler to have a keyboard shortcut that says “hide the mixer, pull up the arranger view, and have the piano roll editing window ready to go” and after doing your edits, having another shortcut that says “hide all that other stuff and just give me the mixer.”
DIGITAL METERING LIMITATIONS
And finally . . . they may be digital, but you can’t always trust digital metering: As just one example, to indicate clipping, digital meters sometimes require that several consecutive samples clip. Therefore, if only a few samples clip at a time, your meters may not indicate that clipping has occurred. Also, not all digital gear is totally consistent—especially hardware. In theory, a full-strength digital signal where all the bits are “1” should always read 0 dB; however, some designers provide a little headroom before clipping actually occurs—a signal that causes a digital mixer to hit -1dB might show as 0dB on your DAW.
It's a good idea to use a test tone to check out metering characteristics of all your digital gear. Here are the steps:
- Set a sine wave test tone oscillator to about 1 kHz, or play a synthesizer sine wave two octaves about middle C (a little over 1 kHz).
- Send this signal into an analog-to-digital converter.
- Patch the A/D converter's digital out to the digital in of the device you want to measure.
- Adjust the oscillator signal level until the indicator for the device being tested just hits -6dB. Be careful not to change the oscillator signal level!
- Repeat step 3 for any other digital audio devices you want to test.
In theory, all your other gear should indicate -6dB but if not, note any variations in your studio notebook for future reference.
Craig Anderton is Editor in Chief of Harmony Central and Executive Editor of Electronic Musician magazine. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.