What You Need to Know About Audioease Altiverb 6 IR Impulse Responses Complete Library: A Guide for

An impulse response is a sample of the reverb generated by the space/gear in question in response to a particular sound - a sine wave sweep in the case of Altiverb's IR library. By convolving (combining) this impulse response with the audio input, incredibly authentic 'real-world' reverb is simulated. That, in a nutshell, is the Altiverb reverb plugin.

audioease altiverb 6 ir impulse responses complete library

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The Yamaha SPX90 Reverb Impulse Responses for Altiverb are a complete package of this classic Yamaha effects units reverb presets. A total of 8 reverb patches are included. The recording of these impulse responses was done with very careful calibration, through a Focusrite digital audio interface, and recorded into Harrison Mixbus 32C.

The world of impulse responses is ripe with possibilities and I hope this article has motivated you to explore and experiment. In a way, using IRs is like spatial sampling. As with field recording, your memory of the place, the process and the result will remain forever linked.

Convolution reverbs are new and recent in the history of this effect. The nicest part about this type of effect is that impulse responses are used in the spatial context of your effect, which allows you to recreate more accurately how a reverberation would occur in a given environment.

Most other convolution effects provide a large collection of built-in impulse responses. And while Convolver does come with over three hundred IR samples, it maintains modesty to lower its price. So, if you want a high-quality, straightforward convolution effect that can load custom samples, Convolver is an ideal choice.

As with most other technologies, many people will be content to use the IRs (impulse responses) bundled with their particular playback device, and to download other free ones from the Internet. (I provided a list of suitable sites for convolution reverb plug-in owners in my recent round-up of PC Freeware in SOS July 2004). While capturing your own impulse responses to the standard of commercial libraries may be daunting, it's not particularly difficult to get respectable results with a little gear, and you don't have to restrict yourself to the usual halls, churches, and studios either.

There are three main sources of convolution impulse responses. The easiest thing to sample is a software plug-in chain, since this can be captured entirely within a single software application, as shown here using Wavelab as an example.Capturing the sound of a hardware device is only slightly more difficult, requiring a soundcard send-return loop to be set up.Capturing the sound of a real acoustic space generally requires a loudspeaker and microphone combination, although some acoustic noise sources can also be used in place of the loudspeaker.

They can even be generated by some utilities. For instance, for PC users there's Voxengo's Deconvolver (reviewed in SOS October 2004), which is a generic $23 utility which can generate swept-tone test signals that you can transfer to any audio playback device for use in the field. You can then use any DAT or other audio recorder to capture suitable response recordings, and Deconvolver can convert these recordings back into impulse responses. Since most people will end up with loads of test recordings, there are batch-processing options in the software to convert them all in one hit.

For more realistic sampled instrument libraries, Tascam's Gigastudio 3 uses its Gigapulse convolution engine to provide Pedal Up and Down resonances for its latest Gigapiano II library. You can also use the same convolution technology to model different mic responses, as shown here.

First, the vast majority of files tend to be 16-bit, and all of these compromise the dynamic range of 24-bit signals being treated. Second, and rather more obvious in many cases, I've noticed many signs of poor set up, with high levels of background noise, missing reverb tail ends, or still vaguely audible test-tone whines (again most obvious near the end).You don't have to limit yourself to reverb when using convolution plug-ins. Any audio files can be loaded in as an impulse response, providing a vast range of complex effects. Here you can see some of the 863 effects of the Spectral Relativity library (reviewed in this article) loaded into the freeware SIR plug-in.

If you're considering buying IR libraries, not all convolution playback plug-ins may be totally suitable. Waves IR1 for instance only supports responses up to six seconds in length, and any library response longer than this will be truncated as shown.

Unfortunately, this restriction will prevent you from using many of the excellent responses from the commercial IR libraries reviewed here, except those in the deliberately shorter collection provided by Kaleidoskopy. Nuendo's Acoustic Stamp convolution engine similarly has an arbitrary 12-second limit, although this has far fewer library implications. Another thing to look out for is that the Reverse function of Trillium Lane's TL Space truncates any IR longer than five seconds.

Prosoniq's Rayverb is slightly unusual in not being a standard convolution player. Instead, it uses 'inverse raytracing' to model real acoustic spaces, and provides comprehensive control over its room model. This makes it extremely versatile for reverb purposes, and you can still import and analyse third-party library files (although both Mac and PC versions only accept AIFF files), but they will be interpreted by Rayverb 's algorithms, and will probably sound completely different from what their developers originally intended.

If you fancy having a go at capturing your own impulses, each developer that offers a suitable convolution test signal will also generally provide step-by-step instructions on how best to use it, and there are also other more general guides on the Internet. It should go without saying that to capture an acoustic space accurately you need to use high-quality mics, preamps, amplifiers, and speakers with a flat frequency response. Omnidirectional or cardioid mic responses give the best results, although any polar response should work reasonably well.

In general, the speaker that plays your sweep signal (or the starting pistol, or balloon, or whatever) should be placed where the performer would be, while the mic capturing the acoustic response should be positioned in the audience, although obviously they are your impulse responses so you can point things where you like within reason! If you've got a multitrack recorder and plenty of mics you can even try capturing IR surround reverb by simultaneously recording the sweep tone at various different positions, and importing them into suitable surround convolution plug-ins like Waves IR360, Voxengo Pristine Space, or Tascam Gigapulse.

DJ and music producer Grant Nelson (aka Big Gee) has announced the release of his personal collection of Lexicon 480L reverb impulse responses which can now be downloaded free of charge.

Those controls shape reverb with typical settings: duration, room size, mix, EQ, and more. But how do you choose your location, or impulse response? Clicking the location image invokes the impulse response library window.

Developed in partnership with LiquidSonics, the Slate Digital VerbSuite Classics plugin uses Fusion-IR impulse responses to recreate the sounds of classic digital reverbs, many from the 1980s. These eight libraries are based on the EMT 250, the classic Lexicon 480, Neve RMX-16, Eventide SP2016, Quantec Room Simulator, the Sony DRE 2000, the coveted TC Electronic TC6000, and finally, the Bricasti M7. 2ff7e9595c