How much time and attention do you give to reverb? Probably not enough. Adding reverb is like adding another instrument to your mix, in some cases taking up as much or more space than another player. Before we dive in to how you can improve the sound of your ‘verb, let's quickly revisit the main parameters of a typical reverb (hardware or software).
‘Verb Parameters
Algorithm: sets the style of reverb such as Hall, Plate, Ambient, Inverse, Spring, etc. If you are under age 30, Google Plate Reverb and Spring Reverb. These were physical devices designed to emulate reverberation.
Reverb Time, a.k.a. Decay Time: Sets length of the reverb tail. For nerds: the amount of time it takes for the reverb to decay by 60 dB after the source has stopped, thus the term "RT60."
Predelay: A small amount of delay that precedes the reverb, typically 0 to 100 milliseconds (mS).
Reverb High Cut: Determines the high-frequency limits of the reverb. This may be called Damping or High Color. In some cases there are separate parameters for High Cut (roll-off frequency) and Damping (amount of cut in dB).
Early Reflections: This parameter gives you separate control over the early reflection component of the reverb – its first slap.
Diffusion: Diffusion is often misunderstood and requires a bit of explanation. First, we have to recognize that reverb is actually a huge number of individual reflections (echoes) of sound. There are so many of these reflections that our brains generally cannot separate them. Depending upon whom you ask, diffusion controls the "separate-ness" of these reflections from each other, or it affects the density of reflections over time. Got that? If not, play with the settings and use your ears.
Thanks for the Complement
Building a reverb program to complement your artist's mix requires consideration of song tempo and band instrumentation. Generally speaking, faster tempos require shorter reverbs to prevent a mix from losing definition. Similarly, when you have sparse instrumentation, you can get away with longer reverb times.
Having said that, we also need to keep in mind whether we are creating reverb for monitors or for the house mix, and whether the reverb is intended to create space or is used as an effect. Ear mixes are more critical because your artist tends to hear the high-frequency detail that would otherwise be lost in the stage wash and, as we know, onstage sound is often completely different from the sound in the house.
For a front-of-house engineer, the performance environment has to be considered when creating reverbs. Unlike a studio situation – where there may be little or no live room sound – the venue puts a critical sonic stamp on the mix, sometimes for better and sometimes for worse.
Reverb Preferences
While there are no rules when it comes to reverb, there are some popular opinions. Many engineers start with a Plate algorithm for percussion because plates tend to be short, tight and have a lot of high-end sparkle. If you're in a theater with a lot of drapery and plush seating, you'll actually be able to hear this, but large rooms tend to overpower artificial reverb.
A lot of engineers start with a Hall algorithm for vocals, because they tend to be warm, full and flattering to a lead vocal. In either case try to make the artificial ‘verb complement the room sound. In concert halls, low-mids tend to bounce around so it might makes sense to EQ some low-mids out of the reverb to prevent the vocal sound from getting muddy. Using the reverb high cut in the vicinity of 4 to 5 kHz helps maintain clarity and avoids "spitty-ness" on vocals and snare.
The truth is that most of the rooms we are trying to emulate wouldn't have much high-frequency component to the reverb above 4 or 5 kHz anyway. For the house mix I often roll off anything below 200 or 300 Hz in a reverb to (a) avoid mud and (b) prevent leakage from kick drum and bass amp in the vocal mic from creating low frequency rolling of the reverb. However, if you did this in an ear mix, your artists might complain that the vocal sound is thin (and they'd probably be right. Imagine that). An artist who is sensitive to reverb emulating their environment might want a predelay approximating a round trip off the sidewalls of the venue. That being the case, you can estimate one millisecond of delay per foot of distance then subtract 10 percent, and it will be pretty darn close.
Tweaking the ‘Verb
Parameters such as a low or high ‘multiplier' or crossover frequency allow you to tweak reverb time within certain frequency bands. "Reverb time" generally pertains to midband decay, but having separate control over the low- and high-frequency decay times is beneficial. A high or low multiplier parameter can tighten up the respective decay times to complement the venue while maintaining a longer decay in the midrange. Ditto for the crossover function found on more advanced (i.e. expensive) reverbs. Adding a lot of reverb creates distance from a sound, opposing the idea of keeping of a lead vocal up front. So if you need a lot of reverb on a lead vocal, keep it short and bright.
Predelay can be used as a way to create larger spaces by postponing the onset of reverb (without increasing reverb time), creating separation between the original sound and the reverb (useful on tambourine or side stick in a ballad). Predelay is also key to big 1980s snare drum sounds so the next time you're on that Poison/Warrant tour, try an SPX 990 Hall program with a 50 mS (or longer) predelay and a 1.5 second reverb time. Higher predelay times (100 mS plus) can take ‘verb from subtle to special effect, which is not uncommon for snare. To add some high-end snap to your snare reverb, send more of the snare bottom mic to the verb, and if you're looking to be more creative try reverse reverb.
Back At Ya
Early reflections are the initial "bounces" of sound from the closest boundary in a room to a listener, a huge cue to the human brain about environment size. (The brain interprets longer spacing between ERs as a larger space). Early reflections can be a component/parameter of a Hall or Room reverb, or could be the algorithm – in which case you won't really get reverb. Early reflections are your friend, because they suggest space without rolling decay. Added to a vocal or an electric guitar, ER can add a bit of girth, and an almost subconscious feeling of space. If early reflection levels are a component of a reverb algorithm, it's worth a listen to what happens if you reduce the ERs to minimum – which can sometimes make a reverb less natural for an effect (in fact a unique part of real plate reverb is that plates provide no early reflections). Some artists like early reflections that mimic the performance venue to avoid a feeling of isolation in their ear mixes.
Whether they are hardware, plug-in or served via outboard CPU (e.g. Waves' MultiRack), different reverbs have distinctly different flavors. For example, tc electronic has a reputation for their early reflections while Lexicon is known for the tails on their high-end hardware ‘verbs (and I'm taking my PCM70 to the grave). Back in the day, the AMS RMX-16 cost a small fortune but had a very distinct sound that was difficult to find elsewhere. Ditto for the Klark Teknik DN780, which remains one of my favorites, and is found in Midas digital consoles. Yamaha's newer REV-X algorithms are now part of Yamaha's digital consoles, and their earlier units such as the popular REV-7 and SPX series had easy-to-use presets and are still found in outboard racks everywhere.
Next month we'll look at other effects and how you can maximize them. In the meantime, don't take reverb for granted.
