How to make proper decisions regarding type and amount of reverb when mixing on headphones.
In the previous post, we discussed the concept of creating dimensionality in a mix and the tools we have to create a three-dimensional soundstage. In this post, we’re going to discuss practical applications of reverb what to listen for when using headphones.
THE LONG TAIL OF REVERB
Nothing makes judgments regarding the application of reverb in a mix easier than headphones. However, since you’ll be able to hear those long reverb tails clearly, you’ll either be tempted to go overboard, because the reverb sounds so good, or you might dial back the amount of reverb because it’s so clearly audible. What’s a mixer to do? While both warnings have an element of truth, they fail to mention that it’s not just a matter of quantity of reverb; it’s also a matter of quality. “Quality” in this case refers to the density or sonic texture of reverb decaying over time.
The parameter that controls density varies with different manufacturers. For example, on Lexicon reverbs, “Definition” controls density, whereas on the Sonnox reverb plug-ins, the control parameter is “Dispersion.” What you’re looking for are low-density reverb tails. Think of low-density reverb like Swiss cheese, with lots of holes in it, and high density like smooth peanut butter. In nearly every case, with the exception of a desired special effect, a low-density reverb is preferable.
Sonnox Oxford Reverb
REVERB IS NOT JUST FOR SPEAKERS
Reverbs in a mix don’t live in isolation during playback over speakers. They actually join with the natural reverb of the room. If you use a thick, creamy-smooth reverb, it will combine with the room’s reverb and pull its associated instrument backward in the mix. The larger the room, the more its natural reverb combines with the mix reverb. The holes in a low-density reverb will be filled with the room reverb, creating a seamless join, and will have the effect of bringing the parent sound closer. The isolation afforded by headphones takes this phenomenon out of the equation, but it should be taken into account in order for your mixes to translate properly to speakers. Therefore, as a basic rule, stick with the low-density reverbs.
Another thing to consider is that long, smooth reverb tails require more volume to hear, which in turn takes up more space in the mix, plus, they have a masking effect on all surrounding sounds. Since we have limited space in a mix, anything that isn’t heard is just wasting resources—and that provides a clue for determining the length of reverb tails. Once a reverb tail is no longer heard in the mix, there’s no reason for it to continue beyond that point.
When deciding the length of a reverb tail, make sure you end it in a musical fashion. For example, if a reverb tail continues for two measures, but is only heard for one, end the tail on or slightly after the downbeat of the second measure. Ending it before the downbeat will create an unmusical empty space with the uneasy feeling of stopping short, but extending it to the downbeat will have the effect of a wave pushing the rhythm to the next measure.
WIDENING EFFECTS OF REVERB
A trick for adding stereo width to a sound with reverb is to create two aux tracks in your DAW and use a different reverb plug-in on each aux track with different types of reverb. Pan one aux reverb left, the other right, and assign the dry sound source to each. You can further expand on this concept by using three mono reverbs, which is based on a technique created by 23-time Grammy-winning engineer Al Schmitt (Steely Dan, Toto, Henry Mancini), who would take the mono live chamber reverbs at Capitol Studios and spread as many as eight sends across the stereo field. (Hard left/right, center, a couple mid left-center, and couple mid right-center. More than likely, Al used as many as eight mono reverbs to mix large ensembles, assigning different instrument groups to each send based on their actual physical position.
Since we’re mixing on headphones, it will be easier to hear the effects of the multi-mono reverb trick, but before you go all Al Schmitt on your tracks, try using the dual mono reverb to widen synth pads. Save the three mono reverbs for vocals, with a spring reverb up the middle, large room on one side, and medium room on the other. For a good jumping off point, set a 50ms pre-delay on the center reverb, 8ms on the large room, and no pre-delay on the medium room. Of course, you should experiment.
BONUS TIP: ABBEY ROAD REVERB
High-frequency tails of long reverbs can annoy and detract (unless it’s the effect you’re going for). At Abbey Road studios, it’s been a long-time practice to filter high and low frequencies on the input side of reverb aux channels, which creates a subtle, natural-sounding reverb. Try this on vocals: Set a high-pass filter at a -12dB per octave slope to cut everything below 600Hz or so and a low-pass filter to cut everything above 4k-5kHz plus or minus depending on the sound. Et voila, instant Abbey Road reverb.
The important thing to listen for is how the cuts to low and high frequencies make you feel. For example, as you cut lows, apart from increased clarity, pay attention to the emotional impact and feel. You may find the vocal sounding not only bigger, more intimate and nuanced as you increase the center frequency. With high-frequency cuts, remember that 4k-5kHz is just a ballpark number. You might want to leave frequencies up to 6kHz for the sake of bringing out air in an instrument or breathiness in a female vocal. Again, each sound is different and requires some experimentation.
HAVE AT IT
That wraps up our five-part tutorial on mixing with headphones. If you’ve been struggling to achieve mixes that compete with the pros, headphones and calibration software offer you an extremely cost-effective and accurate monitoring solution. Along with achieving a flat response for reliable mix decisions, Sonarworks software headphone and speaker response curves enable you to reference what your mix would sound like across several playback systems to ensure mix translation. In addition, if you mix entirely inside the box, you have the added convenience of being able to “take your control room with you” and mix anywhere at any time. Speaking of convenience, if you’re a travelling engineer, you won’t have to risk transporting your favorite monitors, or spend time getting used to the characteristics of an unfamiliar control room.
Mixing entirely in headphones can solve many environmental problems, but they do not entirely preclude the notion of mixing with monitors. We find that a combination of the two is the best solution. Sonarworks also offers speaker calibration software to improve the performance of budget speakers and provide response curves of several popular monitors to create an affordable means of checking mix translation.
Barry M Rivman • exclusively for Sonarworks
Barry is owner and chief engineer of Sound Suite Studios in Medford, Oregon, and former senior pro audio staff writer for Musician’s Friend.