Soundstage Depth Positioning

Tweaking Reverb Parameters to Effect a Sense of Distance and Depth

By Jon Chappell

With the popularity of ultra-realistic-sounding convolution reverbs, musicians are in a better place than ever to create the illusion of instruments and sound sources appearing at different depths from the listener. The challenge remains, however, to learn how reverb and other processing can place instruments on your virtual soundstage. The Depth Positioning Chart below lists a variety of ways in which you can localize an instrument at near or far distances, using adjustable reverb parameters and other programmable settings also included on many multi-effects processors, synths, and drum programs. Also thrown in are a few mixing, EQ, and microphone techniques.

Reverb Settings

Let’s take a brief tour of what these parameters are, and how to apply them. Keep in mind that not every processor or instrument is going to offer every parameter, and that the names may vary (e.g., “Damping” on one reverb processor might be called “roll-off” on another). If you’re in doubt, compare the chart’s descriptions with the ones in your processor’s manual.

Dry/Wet Level Balance

This sets the amount of “dry,” or unprocessed, signal relative to the amount of reverb. A big “wash” of reverb will position a track toward the back of the soundstage—though it risks making the track sound muddy. For an extremely distant effect, go 100\\\% wet. For up-front, in-your-face tracks, and especially on vocals, go 100\\\% dry. For most applications, this setting will be somewhere in between—for example, 25\\\% wet.

Reverb Decay Time

This parameter adjusts how long the reverberation lasts; a good way to hear reverb decay time is to trigger a single dry percussive sound, like a clave, and listen to the reverb. Decay time is often listed in seconds or milliseconds (thousandths of a second, abbreviated ms). If two sources have similar dry and wet levels, the source with the longer decay will sound farther back; one source has considerably lower levels, then less decay will keep it positioned farther back. Keep in mind, as you crank the reverb pass the five-second mark—just because you’re diggin’ that cavern sound—that many clubs have a natural reverberation of about half a second; many concert halls have a natural reverb up around 2-1/2 seconds.

Reverb Algorithm/Room Size

Digital reverbs use different algorithms (mathematical models) or impulse responses (if it’s a convolution reverb) to simulate arenas, halls, clubs, and other spaces. Choose smaller algorithms or sizes to bring a particular track forward on your soundstage; choose larger ones to push them father back.

Reverb Pre-Delay

In most live concert settings, the first sounds you hear follow a path directly from the instrument (or singer, or P.A. speaker) to your ears. This is the initial dry signal, and is free of natural reverberation. Right on its heels, however, usually 5 to 75 ms later, come a number of reflections, which are sounds that have taken a more circuitous route to your ears—bouncing off the stage, a balcony, or a wall before they arrive at your ears. The total of these reflections make up the overall reverberation.

To simulate the natural lag between the initial dry signal and the first reflections, many effects processors offer a pre-delay parameter. Closer objects have relatively long pre-delays between the time their direct sound reaches your ears and the time you hear any reflected signals. Consequently, increasing pre-delay times can help position some tracks closer. If large amounts of reverb or early reflections follow their respective delay times, however, a track my still some far away, particularly if the overall mix is so complex that the pre-delay might not be noticed.

Early Reflection Delay

Early reflections are the first reflections to reach your ears, and sometimes sound distinct, like little echoes. Like pre-delay, closer instruments will generally have a longer delay between the initial dry signal and the first early reflections.

Early Reflection Density and Level

Sometimes we never hear direct, dry signals from faraway sources. For example, if someone is singing in another room or playing a tuba at the bottom of a canyon (doesn’t everyone go hiking with a tuba?), everything we hear will be reflected. So, if the source must sound really far away, apply mega-amounts of early reflections and reverb, with no dry signal present. Such distant sounds usually have very tight early-reflection patterns, so increase ER density to move sounds backward; decrease the density to bring them forward.

Diffusion and Density

These parameters control the number of later reflections, the spacing between them, and how distinctive sound. For sweet, smooth reverb, engineers refer high densities and high diffusion. Reducing them, however, can help position attract closer (though the reverb might sound more "chattering" then smooth). Typically, precaution uses more diffuse and dense settings than vocals.

Reverb EQ

In real life, high frequencies tend to lose energy more quickly than low frequencies; that’s why foghorns can be heard for miles. Reverberation from distant objects usually has fewer high frequencies, and sounds “darker” than reverb from closer objects. If your reverb offers a color or EQ control, try experimenting. If it doesn’t, and you’re using an external processor, you could adjust the reverb’s EQ at the mixing console.

Jon Chappell is a guitarist and Associate Editor at Harmony Central. He has contributed numerous musical pieces to film and TV, including Northern Exposure, Walker, Texas Ranger, All My Children,  and the feature film Bleeding Hearts, directed by actor-dancer Gregory Hines. He is the author of  The Recording Guitarist: A Guide for Home and Studio (Hal Leonard), Essential Scales & Modes (Backbeat Books), and Build Your Own PC Recording Studio (McGraw-Hill), and has written six books in the popular For Dummies series (Wiley Publishing).