How to Contribute Your IR
To encourage interest in preserving the sound of unique environments and devices, we have devoted a section of Acoustics.net to user-submitted IRs. We invite you to contribute your own IRs, whether of historical venues, interesting spaces, or of unique audio equipment.
If you have an IR ready to contribute
Click here for our IR Contribution Form. The form has space for your name, professional information if applicable (including links to a website and email), a description of your IR, application notes, a place to post a picture of the environment or device that was sampled, and a link to upload your IR through our FTP server.
What you’ll need to create an IR
Essentially, an IR is a recording of a sweep signal (a pure tone whose frequency changes continuously from low to high frequency) reverberating within an acoustic space or being processed by a device. This tone is then recorded using a microphone (in the case of an acoustic space) or by direct input (in the case of a device).
Waves IR-1 Convolution Reverb Version 2 and IR-360 Surround Convolution Reverb both include a prerecorded sweep signal to use for sampling rooms or devices. Once you’ve recorded the signal in the acoustic space or processed by a device, Waves IR software lets you de-convolve the sample to create an impulse response that can be used in Waves IR-1 or IR-360 Reverb. This impulse response is only compatible with Waves IR products. To create an impulse response using other convolution software, please refer to that software’s documentation.
Tips on sampling an acoustic space
When sampling an acoustic space, a typical setup includes a multitrack recorder, an amplifier and speaker to play the sweep signal into the space, and a microphone (and mic preamplifier, if needed) to capture the sound. On the multitrack recorder, two tracks are used: the first track to play the pre-recorded sweep tone, and the second track to record the signal’s reverberation in the space.
Ideally, the speaker, amplifier, microphone, and microphone preamplifier 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 best results.
In most venues, the speaker that plays the sweep tone should be placed where the performers would be; on stage in 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.
For more insight into recording IRs, see IR Measurement: An Engineer’s Personal Story
Tips on sampling a device
When sampling a device, you don’t need the amplifier, speaker, or microphone. Instead, connect the output of the track playing the sweep signal directly into the input of the device. Then take the output of the device and connect this to the input of the second track, which will record the sample. As usual, take care to adjust gain staging to avoid distortion.
How to do it yourself
We are looking for individuals working in studios with access to:
- Plate or spring reverbs
- Live rooms or echo chambers
- Churches or local concert halls
- Or even bedrooms, kitchens or living rooms that you find acoustically interesting
Our goal is to measure and capture them for the IR1 Library.
Waves appreciates your assistance.
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 we do not use aux send, connecting the output of our playback device directly to the plate or spring reverb device.
Connect the output of your source (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…) -> Input of the plate. Output of the Plate -> Input of the recording device (HD card etc…).
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, stereo to stereo.
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, microphone and 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.
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…) -> Input of the speaker. Microphone cable -> Input of the recording device (HD card etc…).
You can use a microphone from any kind, with any Polar patterns (we recommend a Cardiod or Omni directional). After deciding which microphone to use, please set up the microphone with the speaker located in front of the microphones, to achieve the best results.
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.