Make Room for Reverb

Seven fresh algorithmic plug-ins that control space and time
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Since the dawn of modern recording, musicians and recording engineers have strived to capture the most natural reverberation possible. Over time, they’ve harnessed empty churches, manmade chambers, torsion springs, suspended metal plates, audio impulse responses, and sundry DSP algorithms in their quest to conjure aural illusions of spaciousness.

Reverberation technology has come a long way since French cathedrals first wowed the masses with a sound as big as all outdoors. In the past year-and-a-half, a new generation of algorithmic reverb plugins has sprung up to challenge advanced convolution reverbs like Audio Ease Altiverb and Waves IR-1. In this article, Electronic Musician investigates seven recent DSP-based plug-ins for your computer, each taking its own approach to giving your tracks room to breathe and grow.

All the reverbs that follow are available in most popular plug-in formats for Windows and Mac platforms. Their parameters touch all the bases, giving you control over pre-delay, room size, damping, tail decay, and other essential settings. Each is perfectly at home in a pro studio or as part of your in-the-box recording and mixing setup, and each offers unique advantages.


Brainworx bx_rooMS

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bx_rooMS ($199, introduces mid-side (M-S) processing to your mixes by converting stereo data to M-S data, applying reverb, and then converting it back to stereo again. This technique can improve clarity and produce reverb with a wider image than traditional stereo. Like most reverbs, bx_rooMS supplies presets for simulating rooms, halls, churches, plates, and ambient environments. Unlike most reverbs, though, it allows continuously variable shapes and sizes, enabling you to modify them seamlessly using an algorithm called TrueSpace.

M-S resembles surround audio in that signals occurring in the stereo center radiate from a single point, and side channels carry the stereo image’s extremes. Boosting the mid signal narrows the image, and boosting the sides widens it. Applying reverb to only the sides increases the perception of distance, especially when the sides are louder than the center or contain more high-frequency energy.

bx_rooMS comprises two mono reverbs that can process either stereo or two mono inputs. Its M-S section provides continuously variable control over the relative loudness of mid and side outputs to change the perceived width of the wet signal. You can apply fully parametric 2-band EQ to the mid, side, or both channels. You can also independently control filter slopes, frequencies, and gain for each band, and attenuate stereo information below a specific frequency. And you can correct a lopsided image by panning the mid signal wherever you like.

Quickly select virtual spaces in the Reverb Type section, and then adjust Reverb Time, Room Size, and Room Shape. You also get high-and low-shelf Gain and Frequency knobs for damping. Pre-Delay offers up to 200 ms of delay time and lets you position the source signal forward or back. The FX section provides hands-on control of reverb modulation, stereo directivity, and bit-depth quantization for emulating vintage digital reverbs.

At the top of the GUI, the toolbar furnishes A/B/C/D buttons that access four banks storing parameter settings. Because they respond to host automation, they’re handy for changing groups of parameters on-the-fly for different sections of a song, for example. Two more buttons access unlimited undo and redo functions. In the Output section, Fix Mix locks the wet/dry balance as you audition different presets, and Wet Solo lets you audition the reverberated signal only.

Most of bx_rooMS’s 199 factory presets emphasize practical studio applications, with names describing modeled environments or the instruments they’re designed for. Sound-mangling presets that take advantage of the onboard modulation are also plentiful.



Eventide Tverb

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Hansa Tonstudio is a world-renowned studio near Berlin’s Potsdamer Platz. It has been home to recordings by David Bowie, Depeche Mode, Tangerine Dream, U2, and R.E.M., among others. The largest part of the studio was once a concert hall called the Meistersaal, built in 1910 and famous for its reverberant architecture.

Rather than capture the great hall’s sound using convolution, Eventide duplicated it algorithmically with computer modeling. Tverb ($249, reproduces techniques developed by engineer and producer Tony Visconti while recording David Bowie’s vocals for the title track to the album Heroes in 1977. Visconti placed three microphones in the Meistersaal at increasing distances from Bowie. The closest mic captured his voice directly and was processed by a compressor. Gates on the more-distant mics opened whenever Bowie sang loudly enough, with the middle mic capturing the room’s ambience during moderately loud vocals and the farthest mic capturing the entire room’s reverberant reflections whenever he belted it out.

Visconti teamed with Eventide to create Tverb, which emulates the hall, mics, and processors used for the “Heroes” session. Its GUI graphically represents the Meistersaal and the console’s relevant controls. When your cursor is over the closest mic, a tiny dialog box pops up for adjusting its polar pattern (cardioid, omni, or figure-8) and enabling high-and low-cut attenuation. You can reposition either omnidirectional room mic by clicking and dragging it anywhere you want and solo the mic as you drag it. When your cursor is over a room mic, you’ll see its exact distance from the control room (up to 70 feet deep) and from the center of the hall (up to 50 feet right or left).

Tverb’s console section displays master room controls and three mic channels. There you can adjust the room’s diffusion, decay, and two bands of EQ and automate changes in your DAW. Each channel has a level fader, stereo level meter, stereo balance knob, and mute, solo, and invert buttons. Channel 1 places a virtual analog compressor, and channels 2 and 3 place linkable gates downstream from the reverb.

Because it was designed to replicate a specific scenario, Tverb’s versatility surprised me. It comes with 123 presets designed to enhance your tracks in almost any situation. Many presets were developed by an impressive roster of engineers, including, of course, Visconti himself.


Exponential Audio Nimbus

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Nimbus ($199,, from the maker of the deep and versatile multi-effects plugin Excalibur, is an extraordinary reverb plug-in with a personality all its own. Based on the core engine of Exponential Audio’s PhoenixVerb, Nimbus is notable for its CPU efficiency and broad parameter set. Most of its more than 1,200 presets sound remarkably natural, and an assortment of features let you fine-tune those presets to best suit the task at hand.

You can lock pre-delay and reverb delay times to any beats-per-minute value you enter by either typing it in or using the tap-tempo button, or you can lock them to your host DAW’s tempo. You can even sync delay times to note values when sync-to-host-tempo is disabled.

In most presets, so-called Warp effects are disabled by default. Enabling them gives each preset a dual identity. The Warp section offers overdrive with three types of distortion. A crossover applies overdrive below a specified frequency and lets you attenuate how much is applied above that frequency. Warp also has bit reduction for simulating vintage reverb units and a compressor/expander with controls for threshold, knee, gain boost or cut, attack time, and release time.


Nimbus lets you specify EQ curves separately for three stages: input signals, early reflections, and the reverb tail. Each EQ stage has -6 and -12dB/octave lowpass and highpass filters, a bandpass filter, and a notch filter. The three curves are graphically displayed with color-coding to reflect any changes you make, along with a live display of the overall audio signal.

Early reflection parameters let you choose from six reflection patterns, determine the distribution and duration of reflections, and filter later reflections relative to earlier ones. In the Attack section, you can specify the reverb type, distribution and duration of the attack, and size and density of the diffusion surface, as well as filter later portions of the attack. The Tail section lets you control room size, reverb balance between low and mid frequencies over time, duration between early reflections and reverb tail, width of the tail’s stereo image, damping factor and frequency, and dynamic tail suppression parameters. Tail suppression uses its own compressor to enhance clarity by lowering reverb levels during loud audio passages and allowing the tail to bloom during quiet passages.

Additional details make Nimbus a pleasure to use. Clicking on the + button more than doubles the GUI’s size. You can mark your favorite presets and enable Tooltips to help you learn your way around. It’s also easy to scroll through banks of presets and presets within banks using only your computer’s keyboard. With so many thoughtful features, excellent room simulation, and extensive functionality, I could easily imagine Nimbus becoming anyone’s reverb of choice.


FabFilter Pro R

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Steeped in black, with blue, orange, green, and white highlights, Pro R ($199, certainly has an attractive and easy-to-use GUI. It also offers much-appreciated resizing options, with a choice of three fixed sizes and a full-screen view. Seven knobs in the upper section handle most essential parameters, with some doing double duty to simplify operation and speed workflow. Below those, the Decay Rate EQ section displays a continuous curve showing how reverb decays across the frequency spectrum, and the Post EQ section displays a similar curve showing overall reverb equalization. Double-clicking on either curve adds a node for a new band, which you can drag to create as many as six high/low shelf, notch, and bell curves.

The all-important Space knob fades between room types and controls reverb decay time simultaneously. Decay Rate varies the decay from half to twice the Space knob’s decay value, and the Brightness knob controls damping. The Character control (which I find slightly mysterious almost anywhere) appears to increase early reflections and add faint LFO modulation to the reverb tail. Stereo Width varies from mono to full stereo to dual mono, and Distance moves the perceived sound source within the modeled space by affecting early reflections and tail diffusion.

You can double-click on any control to type in exact values, including either pitches or frequencies. Alternatively, you can type in “2x” for twice the current value or “75%” for three-quarters the current value, for example.

Some of Pro R’s most thoughtful controls appear at the GUI’s top and bottom. Undo and redo buttons let you step through your edit history as many times as needed. A helpful frequency analyzer displays two real-time frequency-distribution graphs superimposed over one another, showing either the audio signal before and after applying reverb or the post-reverb signal and reverb decay. A/B snapshots allow you to audition variations on your current settings and copy and paste between them. Another useful detail is MIDI Learn, which lets you assign physical controllers to Pro R parameters.

Clicking on Sync Predelay synchronizes the length of pre-delay to your DAW’s tempo in rhythmic subdivisions from 16th to quarter notes. You can also scale the pre-delay in triplet or dotted note values using Predelay Offset. Pro R comes with a large selection of excellent factory presets that include instrument-specific ambiences, an assortment of room simulations, and tempo-synced grooves and slapbacks appropriate for beats and vocal tracks.


PSPaudioware PSP 2445

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PSP 2445 ($149, is a thoroughly convincing emulation of two classic digital reverbs, the EMT 244 and EMT 245. Elektromesstechnik, which developed the first plate reverb in 1957, marketed the rackmount units as simpler, more compact successors to the company’s sought-after, 99-pound EMT 250 Electronic Reverberator. The EMT 244, introduced in 1979, had stereo 13-bit A/D/A conversion and a maximum 4.5s reverb time. The EMT 245, which replaced it two years later, added the ability to vary pre-delay time and the level of early reflections. In creating PSP 2445, PSPaudioware borrowed the sound and parameter set from EMT’s vintage hardware and extended them.


A 20-position knob in the GUI’s center selects reverb duration from 0.2 to 5 seconds, and a 15-position knob selects pre-delay up to a maximum 84ms. The Reflections knob determines how many early reflections occur ahead of the tail, and you get separate sections for controlling input and output gain. Using two switches, you can select longer reverb for low frequencies, shorter reverb for high frequencies, or both. Additionally, a small 3-position knob lets you choose between the 244 and 245 reverb engines or combine them.

Opening a hidden panel reveals more controls, including switches for swapping the stereo outputs of either or both reverbs and knobs for controlling modulation depth, engaging a highpass filter, adjusting stereo width, and determining reverb duration independently for low and high frequencies.

Other than its sterling sound, PSP 2445’s primary advantage is its simplicity. Granted, you don’t get the deep programmability of some other plug-ins discussed in this article, but it’s every bit as usable in the studio. A relatively limited selection of 33 factory presets furnishes straightforward, practical simulations, including some remarkably credible plate reverbs.


Waves Abbey Road Reverb Plates

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From the outside, the EMT 140 Plate Reverb isn’t much to look at, because it’s completely enclosed in a heavy 8 x 4 x 1-foot composite wood box with no openings other than jacks at one end. Inside, a large steel sheet (the plate in plate reverb), half a millimeter thick, is suspended by springs from a steel frame. A tube-amplified driver resembling a loudspeaker coil is attached to its center. Vibrations emanating from the driver radiate through the plate and are captured by two piezoelectric pickups, converted to line-level signals, and sent to a tube-based output amplifier, producing extremely lifelike artificial reverberation. A remote-controlled servomotor changes the proximity of a fiberglass pad to dampen the plate’s vibrations, giving the user control over the tail’s duration.

Abbey Road Studios acquired four EMT 140 units in 1957 and labeled them A, B, C, and D. Studio staff replaced the output amplifiers on A, B, and C with custom solid-state/tube amps to minimize noise. Since then, these reverb units have been integral to recording sessions for The Beatles, Adele, Pink Floyd, and innumerable film scores, among others.

To create Abbey Road Reverb Plates ($249,, Waves modeled each of the four units in a single plug-in that delivers the kind of smooth, complex sound you’d expect from real plate reverbs. Its GUI displays a graphic representation of the EMT 140’s interior in the upper half and retro-looking knobs, dials, and faders in the lower half. The factory presets do not emulate particular environments like nightclubs, churches, or caves. Instead, you get 44 terrific presets designed for specific instruments and 10 more for vocals.

Two Input faders let you adjust stereo gain either separately or linked together, as do the two Output faders. The Plate Selector dial chooses one of the four plate models, and the Damper dial offers 11 positions from 1 to 5.4 seconds. The 4-position Bass Cut dial models the highpass filter on the original units, and the Treble knob models the high-shelf filter on Abbey Road Studios’ EMI mixing consoles. When needed, much-appreciated undo and redo buttons step through your edit history. Other details contributing to the plug-in’s realism include the ability to dial in modeled harmonic distortion, hum and noise, and crosstalk between stereo channels. Using Abbey Road Reverb Plates comes as close to working with real hardware as any reverb plug-in I’ve seen.


Zynaptiq Adaptiverb

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Most reverb plug-ins give your tracks a sense of space by simulating environments of various shapes and sizes. Although Adaptiverb ($249, does that, too, it can transport you much deeper into experimental sound-design territory. Like most reverbs, it uses allpass filtering to create traditional room simulations, but it also exploits a technology borrowed from graphic imaging called ray-tracing. Adaptiverb’s raytracing engine models a room in three dimensions and simulates the paths of thousands of sound waves traveling throughout the room from a pair of sound sources to the listener. The resulting reverb is linear across the entire audible spectrum.

Adaptiverb’s most astonishing trick is getting reverb tails to match the source material’s tonality. Its Bionic Sustain Resynthesizer (BSR) generates tails you can actually tune to whatever chord or scale you choose. BSR uses hundreds of oscillators that rely on machine learning to recognize and reproduce the input signal’s harmonic content while filtering out noise and inharmonic transients.


Additionally, by removing frequencies from the tail that are no longer present in the source audio, Adaptiverb maintains harmonic clarity and sharpens melodic definition using Harmonic Contour Filtering (HCF). Conversely, it can suppress frequencies the tail has in common with the source, if you prefer. A Freeze function holds the current state of the input signal and the BSR oscillators by looping the input buffer. As it loops, you can adjust numerous parameters to generate some intriguing timbres and textures.

Adaptiverb’s GUI has separate sections for managing presets, changing input and output parameters, specifying BSR and HCF settings, accessing functions such as enabling zero latency and viewing the entire signal flow, and adjusting the reverb model, source, size, and damping. The Harmonic Filter Mode controls are especially remarkable, because you can graphically choose which pitches pass and which are suppressed and then save five snapshots of those settings for later recall.

In the GUI’s center, the X/Y Control lets you vary the reverb mix and sustain continuously. Switching the view mode from Fine-Tune to Main hides the BSR and HCF controls and replaces them with two unusual trackball sliders for Richness and Harmonic Filtering.

Adaptiverb comes with more than 400 presets ranging from excellent room simulations to evocative drones and fascinating but indescribable effects. Presets conveniently respond to MIDI Program and Bank Change messages, and MIDI Learn allows you to assign external controllers to all functions.

Unrestrained by the normal laws of nature, Adaptiverb brings reverb more fully into the realm of shaping sound harmonically and texturally. Just as synthesizers blend ingredients to cook up innovative sounds, visionary plug-ins like Adaptiverb give us the tools we need to excavate new ground and explore unfamiliar timbral territories.