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October 1, 2001

Kind of Loud did a nice job of eliminating zipper noise.

Plenty of good reverbs are available, both hardware and software. Most have many attributes in common, defining a standard method for creating the illusion of space in a mix. With modeling technology all the rage, it's no surprise that someone devised a reverb technology based on modeled spaces and materials. The result is a truly great-sounding reverb and a new way of thinking about defining spatiality.

RealVerb Pro 1.1 is designed for TDM systems, and a functionally equivalent version is included with Universal Audio's Powered Plug-Ins software and digital signal processing (DSP) card bundle ($995). Kind of Loud also offers RealVerb RTAS ($249) and RealVerb MAS ($249), as well as RealVerb 5.1 ($795) for surround-sound reverb in TDM environments.

RealVerb Pro requires Digidesign's Pro Tools 5.1 or later. The older RealVerb TDM ($495) is required and still available if you're running Pro Tools 4.3 or 5.0. Scaled down a bit to accommodate the lack of DSP, the Real Time AudioSuite (RTAS) and MOTU Audio System (MAS) versions offer fewer reflections and no diffusion control.


At the core of RealVerb's design is the concept that you choose what physical materials make up your virtual environment. That environment dictates the relative decay rates of different frequencies. RealVerb uses standard acoustic measurements of the absorptive properties of real-world materials to calculate decay-rate characteristics.

Acoustical law says that the more a given frequency is absorbed, the faster it decays. Conversely, the less a frequency is absorbed, the slower it decays. That approach to simulating physical surroundings yields virtual spaces that sound more realistic than simply dialing in some EQ on traditional reverbs.

RealVerb offers a pair of pop-up menus to select two room materials from a list of 36, including marble, carpet, plaster, glass, concrete, hardwood, air, seats, and audience. Graphics representing those materials appear in a split window; change the balance of the two materials by dragging the split point (see Fig. 1). The Thickness slider determines the response of the selected material's natural reflective and absorptive qualities. Positive values exaggerate properties, and negative values invert them. A setting of zero means that all frequencies are absorbed equally. (For a look at RealVerb's use of artificial materials, see the sidebar, “Artificial Reality.”)

A similar construct lets you choose not just one room type and size but a blend of two; for example, you can combine a large dome with a small A-frame. The two selected rooms are combined into a single conceptual room (as opposed to simply adding the two results together at the output). Other shapes include cube, shoe box, corridor, and horseshoe. The plug-in provides artificial room types such as spaces realized with springs and various plates. The distance from the sound source to the opposite wall of the room can be as little as half a meter or as great as 99 meters.

Although your selection of materials largely dictates the environment's tonality, RealVerb's 3-band “paragraphic” EQ lets you change the resonance of the virtual space. The equalization curve is determined by the amplitude at four frequency points — two defined by the user and one at each end of the audible spectrum.


RealVerb's Timing panel displays the selected materials' early reflections and late-field reflections in two graphs. The separate display of those attributes is especially handy when constructing environments in which the two overlap.

By dragging the rectangular early-reflections envelope, you change the amplitude (the vertical axis) or delay between the direct sound's arrival and the onset of early reflections (the horizontal axis). Late-field reflections are contained in a triangular envelope, the slope of which dictates the decay of the reverberation tail. Dragging the upper vertex of the triangle changes the amplitude, onset time, and reverb time. You can also enter numbers to manipulate both graphs. Another control in the Timing panel determines how quickly the late field's density increases.

RealVerb's Positioning panel is an area in which the product shines. With most reverb hardware and software, you adjust reverb amount and predelay to try to simulate the source at a distance. In another example of real-world thinking, RealVerb employs a distance model that controls the mix of direct and reflected energy according to the Distance control's setting. The Direct Panning control determines the direct signal's width.

RealVerb offers controls for separately placing the early- and late-field reflections within the stereo field. The Early and Late sliders each have handles for determining extension into the left and right fields, providing precise control of stereo imaging. You can also grab anywhere between the handles and drag the stereo image farther right or left. RealVerb 5.1 replaces the positioning sliders with surround-sound positioning circles.


One problem that sound-effects designers encounter is transitioning between spaces — a car speeding out of a garage or someone walking through a doorway to a radically different environment, for instance. The typical solution has been to blend the outputs of the two environments. Consider an example cited in RealVerb's documentation, in which one room has 10 ms of echo and another has 100 ms. Traditional methodology would blend them with each at half power. RealVerb includes a morphing feature that averages the two values, yielding an echo of 60 ms at full power, perhaps.

Automating the Morphing slider allows smooth transitions between the two presets. You can select the morphing source presets only from RealVerb's root directory, not from its hierarchical folders. Consequently, you might need to copy some of the presets prior to morphing.

RealVerb's controls are continuously adjustable. Kind of Loud did a nice job of eliminating zipper noise and other digital artifacts when you change controls in real time.


RealVerb sounds, well, real. Although not quite as lush as the TDM version, the RTAS and MAS versions still deliver possibly the richest native reverb around. RealVerb ships with a nice assortment of presets to get you started, as well as a PDF manual that includes a welcome technical appendix covering some reverberation concepts.

Kind of Loud has provided a tool that lets musicians and engineers think about creating acoustic spaces in a more organic way. Whether you want a marble bathroom or a concert hall filled with people, it's much easier to define a virtual environment by its physical attributes than to mimic one with the controls on a traditional reverb unit. The ability to position and move the source, as well as morph between spaces, is a tremendous boon for sound design.

Kind of Loud also struck a good balance with the software's interface. After all, true environmental modeling can be as involved as constructing three-dimensional models in the computer-graphics world. RealVerb doesn't let you design exact room shapes or place different materials on specific surfaces, but it strikes a manageable balance.

RealVerb is an excellent product for any mixing application. Until now, technology conventions conditioned most people to think about spatial simulation in artificial terms. Ironically, it takes a bit of adjustment to think about the process as defined by RealVerb. Ultimately, the results are more natural, both conceptually and sonically.

Jeff Burger is a songwriter and producer based in Sedona, Arizona.


Kind of Loud
RealVerb Pro 1.1 (Mac; TDM)
reverb-modeling plug-in



PROS: Realistic reverberation. Smooth audio even when moving controls. Preset morphing. Source positioning. Intuitive interface.

CONS: PDF documentation only.


Kind of Loud Technologies
tel. (831) 466-3737

Minimum System Requirements

RealVerb Pro

Mac 9500; 128 MB RAM; OS 9.0.4; Pro Tools 5.1 TDM; Mix card; CD-ROM drive


In addition to dozens of standard materials, RealVerb Pro 1.1 also includes a variety of artificial materials named according to given frequencies. To fully understand the naming conventions used for those artificial materials, some background is needed.

In nature, high frequencies decay faster than low frequencies. In technical terms, T60 is the time it takes the reverb tail of the signal's low frequencies to reach 60 dB below the source level. High frequencies decay at a rate of T60/10. The frequency in the name of one of RealVerb's artificial materials represents the rolloff point between those two realms. A material specified with a property of 8 kHz, therefore, means that all frequencies above 8 kHz will roll off ten times faster than the frequencies below 8 kHz.

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