Waves Parametric Convolution Reverb
IR-1, IR-L and IR-360
User’s Guide
Waves IR-1 software guide page 1 of 40
TABLE OF CONTENTS
Overview
Synthetic Digital Reverberation
Sampled-Acoustics Convolution Reverberation
The Perfect Hybrid
The Impulse Responses
IR Library
Factory Presets
Sampled Acoustics V2
Virtual Acoustics - Devices and Synthetic
Import Impulse Response from File…
Import Sweep Response from File…
Tips for Sampling an Acoustic Space
MEASURING VINTAGE PLATES, SPRING REVERBS OR ANY REVERB UNIT
MEASURING HALLS, ROOMS
IR-series plug-in channel components About the IR-360:
IR-series Controls and Displays About the IR-L
Reverb Time Convolution start: Convolution Length Ratio
RT60
Dry/Wet control Direct:
Offline Calculation indicator
IR-1 and IR-360 Controls and Displays Reverb Time
Convolution start: Convolution Length Ratio
RT60
Reverb Control Parameters Reverb Density
Reverb Resonance Decorrelation control Dry/Wet control
Wet Properties Direct Signal Early Reflections Reverb Tail Direct:
Direct Gain Direct Predelay ER
ER Gain ER Predelay Tail
Offline Calculation Indicator More About Reverb Damping
Damping HF damping
Waves IR-1 software guide page 2 of 40
LF damping
Reverb EQ
ER Buildup
ER/TR-X Crossover
IR-360 Controls
Toolbar WaveSystem Controls
Loading Impulse Responses
Saving
Importing Impulse Responses
IR Info and Properties
Notes on “Flat Points” or Unity Gain Settings for Controls
System Requirements
Notes CPU about Optimization
IR-1 HTDM
Waves IR-1 software guide page 3 of 40
Introduction
The Waves IR-1, IR-L and IR-360 plug-ins create extremely high quality replicas of acoustical spaces and synthetic reverbs. They also allow the user to alter many aspects of the sound of these reverbs.
For the purpose of this Manual, when discussing attributes shared by the Waves IR-1, IR-L and IR-360 Parametric Convolution Reverb plug-ins, we will simply refer to them all as the IR-series.
Overview
The Waves IR-series are convolution-based reverb processors. They give the user total control of a reverb's properties. Impulse Response Convolution is the process of forcing a certain acoustic signature on any incoming audio signal. An Impulse Response (IR) is created by feeding a very short pulse (Impulse) into a linear system and measuring the resultant output (Response).
Synthetic Digital Reverberation
Historically, most digital reverberation processors have used a synthetic reverberation engine for high efficiency. This would usually consist of two reverberation generators:
•The Early Reflections Generator. This generator is based on a short Finite Impulse Response (FIR) filter with less than 100 reflections. A short stage of convolution is performed with this FIR.
•The Reverberation Tail Generator. This is based on a recursive Infinite Impulse Response (IIR) filter. The IIR comprises a feedback loop with a decay factor and inner dispersion filters. It makes the reverb more complex, less resonant, and more rich and natural sounding.
The tail generator is efficient. It can generate a one-second reverberation time or a fivesecond reverberation time using the same amount of processing power. Such reverbs usually allow a great deal of control over the reverberation properties. These controls have become classics. They include Reverb Time (RT), Predelay, Size, High and Low
Frequency Damping, and Diffusion.
Typically, the goal for using a reverb is to emulate the acoustics of natural spaces such as rooms or halls, or to add "wet" reflections to "dry" sources for creative and aesthetic reasons.
Examples of these reverb processors include the Waves TrueVerb and Renaissance Reverb.
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Sampled-Acoustics Convolution Reverberation
In math, the term convolution means an integral which expresses the amount of overlap of one function x as it is shifted over another function y. In the literal sense, it means to
“roll together” or to “fold together”. A convolution reverb blends together an input signal with another type of audio signal called an impulse response.
Sampled-acoustics convolution processors are a different type of digital reverb than the digital reverbs that preceded them. They are much more calculation-intensive, but offer the ability to faithfully convolve any given impulse response with any input signal.
The Impulse Response (IR) of a certain reverb hardware setup or the acoustics of a real space can be captured and imported into the sampled acoustics reverb. It will use the Impulse Response as a filter consisting of thousands of reflections. The longer the IR, the more intensive the calculation, and thus the more processing power that will be required.
The result is that running a dry signal through a typical sampled acoustics reverb will sound much like running it through the original device with the same settings, or like recording the signal in the sampled space with a microphone setup similar to the one used for capturing the acoustics. These reverbs usually offer very little control of the reverberation properties and are essentially designed to faithfully super-impose the sampled acoustics.
The Perfect Hybrid
The Waves IR-series plug-ins are designed to bridge the gap between synthetic digital reverberation and sampled acoustics convolution reverberation. They provide a convolution-based reverb processor with total control of the reverb parameters. The IR- series uses the impulse response as raw material. This allows the user to process the impulse response with controls that are similar to those offered in classic digital reverbs.
The process is power intensive. However, the manipulations performed on the impulse response are calculated offline so that they don’t consume all of the CPU’s power. Then they are applied by way of straightforward convolution.
The result is that you have the natural and high-quality sound of sampled space acoustics as well as the controls to shape the sound to your needs. These manipulations go beyond those offered in regular digital reverbs.
Waves IR-1 software guide page 5 of 40
The Impulse Responses
Another major part of the IR-series is the Impulse Response (IR) Library. The library offers a set of high-definition IR’s. Waves paid special attention to this part of the product because it is the basic reverb sound of the IR-series reverbs. We established a special recording setup and method specifically for IR recording. This method provides exceptional signal-to-noise ratio, very low harmonic distortion, and a wide frequency bandwidth (20Hz-32kHz). Thus, it offers optimal sonic depth and dimension.
This method for taking acoustical measurements was developed by Waves in collaboration with Professor Angelo Farina of the University of Parma in Italy. The basis of the acoustic capture method was documented and presented in the AES (Audio Engineering Society) paper Recording Concert Hall Acoustics for Posterity. To see this article, please check out the following link:
http://www.waves.com/objects/pdf/general/article_farina05.pdf
IR Library
The library that is included with the purchased IR-series covers all of the reverberation needs of the most demanding studio professionals. It consists of 4 main parts:
•The Basic IR set is installed with the IR-series. It is available in the downloadable demo as well as in the full product.
•Sampled Acoustics V2 contains a set of world-class Concert Halls, Opera Houses, Cathedrals, Studios and more. These are natural spaces captured in the USA, Italy, Japan, the UK, Israel, Australia, and more. Our original Sampled Acoustics library has been reprocessed with enhanced quality, and new micing techniques were added. In accordance with our vision of continuously expanding the IR library, new venues have also been added to the library.
•Virtual Acoustics - Devices contains Sampled IR’s from classic reference reverb hardware.
•Virtual Acoustics – Synthetic contains synthetically generated or preprocessed IR’s.
Waves IR-1 software guide page 6 of 40
Accessing these IRs is easy. Select the desired preset from the plug-in’s “Load” button, which will present the menu as follows:
Factory Presets is the first section. It is available with the installation of the IR-series, even for demo purposes. The IR data for these presets resides in the folder
"IR1Impulses V2" in a directory called Basic.
The Path is:
Waves Plug-Ins dir/IR1Impulses V2/Basic.
The Custom Setup group contains presets that only have settings. These presets can be loaded onto any IR.
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Sampled Acoustics V2
The presets in this section are based on samples of real places. The contents of the Sampled Acoustics V2 folder on the DVD have to be copied into the IR1Impulses V2 folder inside the Waves Plug-Ins folder. You can add or delete folders from this directory. Each time upon loading, the Plug-In will scan the directory and dynamically build its preset menu according to the folder hierarchy.
Virtual Acoustics - Devices and Synthetic
The presets in the Virtual Acoustics-Devices section are samples of a reference hardware Reverb Unit. The Virtual Acoustics-Synthetic presets are synthetically generated and processed IR’s. The contents of the Virtual Acoustics folder on the DVD have to be copied into the IR1Impulses folder inside the Waves Plug-Ins folder. You can copy the Devices and/or Synthetic folders into the IR1Impulses folder, and the
Plug-In will scan them upon loading.
Import Impulse Response from File…
The IR-series allows you to import your own IR’s. You can sample them yourself, download them from the Internet, or find them elsewhere.
Import Sweep Response from File…
The IR-1 and IR-360 allow you to import the Sweep Response that you record in an acoustical space or hardware device. The plug-in will then process that Sweep
Response into a new IR.
Here are step by step instructions to make your own IR:
-Play your sweep file supplied on the CD and also downloadable from the Waves website (a 15 second sweep followed by 10 seconds of silence) through speakers in the room to be captured.
-Record the result with 1 or more microphones to 1 or more tracks.
-Create a new folder (We'll name it "My Sweeps") inside your "IR1Impulses V2". folder, where the plug-in searches for new IRs.
-Put your recorded sweep files inside your new "My Sweeps" folder.
-Load the IR-1 or IR-360; Press Import Sweep Response From File…
-Guide the browser to the "My Sweeps" folder.
-Load the .wav files one by one as you are prompted by the plug-in.
-After some calculations, an Impulse Response .wir file will be automatically saved next to your sweep files in the "My Sweeps" folder.
-To save this new IR as a preset, press Save, then select Save to New File.
-Navigate to the "My Sweeps" folder.
-Reload the IR-1 or IR-360; The new preset will appear in the load menu.
-Congratulations! You have created a new IR! You may now optionally delete the recorded sweep files from the "My Sweeps" folder.
Waves IR-1 software guide page 8 of 40
Tips for Sampling an Acoustic Space
When sampling an acoustic space, a typical setup includes a multi-track recorder, an amplifier and speaker to play the sweep signal into the space, and one or more microphones (and mic preamplifier(s), if needed) to capture the sound.
Ideally, the speaker, amplifier, microphone(s), and microphone preamplifier(s) used should be as transparent as possible, having flat frequency responses. A microphone of any polar pattern will work, although we recommend cardioid or omni-directional microphones for optimal results.
In most venues, the speaker that plays the sweep tone should be placed where the performers would be; on stage in a concert hall, for example. The microphone should be placed somewhere in audience area; naturally, a microphone placed closer to the stage will capture more direct sound and less reverberation than a microphone placed in the last row. Keep in mind that the presence of a full audience, as well as musicians or musical equipment on the stage, will absorb sound and dramatically change the reverberation quality of the acoustic space.
MEASURING VINTAGE PLATES, SPRING REVERBS OR ANY REVERB UNIT
The measuring procedure is quite similar to a normal voice processing (via the plate or the spring unit). The difference is that we do not use an aux send. Instead we connect the output of our sweep playback device directly to the plate or spring reverb device.
SET UP:
Connect the output of your source (Pro-Tools HD card, etc…) directly to the input of the measured unit. As for the output of the measured unit, connect it directly to the recording device (HD card, etc…)
Output source (HD card, etc…) Æ Input of the plate.
Output of the Plate Æ Input of the recording device (HD card, etc…).
SESSION:
Create two different channels. The first channel will be the sine sweep channel. We use a simple sweep signal, which is a pure tone whose frequency is changed continuously from low to high frequency. The second channel should record the wet signal, which we receive from the plate reverb. If there is more than one setting on the unit please measure them all. For instance, reverb settings (1-5), mono-to-mono, mono to stereo, and stereo to stereo.
Waves IR-1 software guide page 9 of 40
MEASURING HALLS, ROOMS
The measuring procedure of a venue is slightly different than that of measuring devices. Measuring venues requires a larger setup, which includes a playback device, a microphone and a loudspeaker. We can use the same session we were using for the device recordings, only instead, we connect the output of our playback device to a speaker, and a microphone should be assigned to the input of our recording device.
SET-UP:
Connect the output of your source (HD card etc…) directly to or through the mixing console to the loudspeaker. For the input, connect the microphone cable directly to or through the microphone pre amp to the recording device.
Output source (HD card etc…)Æ Input of the speaker. Microphone cable Æ Input of the recording device (HD card etc…).
You can use a microphone of any kind, with any polar patterns. We recommend a cardiod or omni-directional microphone. After deciding which microphone to use, set up the microphone with the speaker located in front of the microphones, to achieve the best results.
MONO SESSION:
To make a Mono IR, create two different channels. The first channel will be the sine sweep channel and should be assigned to the loudspeaker. The second channel should record the microphone signal.
MONO TO STEREO SESSION:
Simultaneously record one speaker (Center) with the Left and Right mics.
FULL STEREO SESSION:
To create a 4 convolution IR, Record your Left speaker with the Left mic (LL) and Right mic (LR). Then record the Right speaker with the Left mic (RL) and the Right mic (RR).
IR-SERIES PLUG-IN CHANNEL COMPONENTS
The IR-series is available in several channel configurations as follows:
Mono to Mono: 1 convolution |
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Mono |
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Mono |
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Convolution |
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Waves IR-1 software guide page 10 of 40
Mono to Stereo: 2 convolutions: 1 left, 1 right.
Left
Mono
Convolution 
Output
Input
Right
Convolution Output
Efficient Stereo: 2 convolutions: Left in to Left out and Right In to Right Out. This component does multi-mono processing.
•With Efficient Stereo, the added control for input channel Crosstalk can keep the channels separate, or sum the wet path input. This component is very practical for stereo-to-stereo reverberation. It provides beautiful reverberation with all the depth and dimension that you might need on an auxiliary stereo reverb.
Full Stereo to Stereo: 4 convolutions, Left Channel to Stereo, and Right Channel to Stereo. This component presents a more purist approach to Stereo Reverberation than
Efficient Stereo, but will use twice the CPU.
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Left |
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Convolution |
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Output |
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Left |
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Input |
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Convolution
Convolution
Right
Input Right
Convolution 
Output
= Summing
Waves IR-1 software guide page 11 of 40
About the IR-360:
The IR-360 is the surround sound version of the IR-1. The IR-360 is HTDM for Pro
Tools TDM Users. IR-360 owners will also receive an IR-1 included in the purchase.
Supported channel configurations of the IR-360: |
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Channel Configuration |
# of Convolutions |
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Mono to 5 Channel Discrete Surround processor |
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4 or 5 |
Efficient Stereo to 5 Channel Discrete Surround processor |
4 or 5 |
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Mono to 5 Channel Sound Field |
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3 |
Efficient Stereo to 5 Channel Sound Field |
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3 |
Full Stereo to 5 Channel Sound Field |
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6 |
Sound Field Surround to Surround |
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6 |
Efficient Discrete Surround to Surround |
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4 or 5 |
Diagrams of these channel configurations are shown below:
Waves IR-1 software guide page 12 of 40
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