Create Custom Impulse Responses with Audio Assault aIR Impulse Rack

If you’ve ever wanted to create your own impulse response for a unique guitar tone, Audio Assault has released a plug-in that allows you to sculpt your own IRs from the ground up. You can use other IRs as a starting point, or for the adventurous, start fresh at step one and fiddle with knobs until your heart’s content. In this post, we’re going to make a brand new IR for a metal guitar sound. Follow the steps later in this tutorial to create custom Impulse Responses with Audio Assault aIR Impluse Rack.

28 July 2020 – Written by Michael R. Myers #mykmyrs

Skill Level: Intermediate

What Are We Doing With aIR Impulse Loader?

We’re going to generate and export a custom impulse response (IR) file with air Impulse Rack. To keep this tutorial brief, I will assume that you have an understanding of what an IR is and how you apply them within your DAW. If you don’t understand IRs just yet, go do some research and come back to continue.

There is not much documentation on the aIR Impulse Rack, so until that becomes available, the steps here are going to be similar to other information and videos I have seen for this product. There’s also the risk that the information presented will be incomplete or incorrect, so make sure you save your preset in a safe place in the event we find out updated information from the Audio Assault team.

What You’ll Need to Create Custom Impulse Responses with Audio Assault aIR Impluse Rack

  • A Digital Audio Workstation. I’m using an evaluation of Reaper v5.
  • An amplifier simulation plug-in that allows for its cabinet section to be turned off so that IRs can be used for speaker cabinets.
  • Paid version of Audio Assault’s aIR Impulse Rack plug-in
  • An alternate IR loader, such as STL Tones’ NAD IR. It’s free and part of the Emissary Plug-In Bundle.

Some Remarks Before We Continue

  • One of the Audio Assault developers posted a video tutorial about aIR Impluse Rack on 25 June 2020 on the Audio Assault User Group on Facebook. In the video, he demonstrated how to blend several different IRs to create a new IR. In addition, he added several components, one at a time, to show how to make your own amp and cabinet simulation. Based upon the latter topic, I wanted to show how he did his steps while tweaking the settings to make my own IR.
  • Audio Assault runs regular promotions on their products, and they are insanely affordable during these promotions. You can pick up aIR Impulse Rack for around $10 USD while it’s on promotional pricing. The best way to be notified of sales is to join their email list and also the Facebook group. Joining other VST/Plug-in groups on Facebook may also allow you to see what others post for sale pricing as well.
  • This link is where you can find this tutorial’s finished IR file if you just want a sample IR without doing the configuration steps in this tutorial.

Steps to Create Custom Impulse Responses with Audio Assault aIR Impluse Rack

  1. Record a dry guitar track 4 bars in length to be used for playback during the IR development process.
  2. Add the aIR Impulse Rack plugin to the dry guitar’s track effects. Set up looping in your DAW for the dry guitar track so that you’ll be able to hear the changes to the IR as we build it.
  3. Add your desired amp simulation to the guitar track. Ensure that you disable its cabinet so that we can use our own impulse response that we are builidng as the cabinet. Here I am using Audio Assault’s Sigma virtual amplifier.Disable Amp Cabinet
  4. Add the aIR Impulse Rack plug-in to the guitar track, after the amp simulation.Load AIR rack
  5. Click the Modules tab in the pane on the right-hand side. The available tools are presented, starting with “IR Module”. Scroll the list until you find “Phase Delay”. Drag in three (3) instances of this module.Config Delays
  6. The delays are going to act as the speaker cabinet. By adjusting their delay knobs, we’re simulating the sound bouncing around inside the cabinet. Set them with the following values, starting from the top instance and working down. Instance 1 – HP 89.1 LP 9996.4 Mix 50 Delay 1.1 Feedback 55.7 Parallel ON Phase ON Power ON. Instance 2 – HP 101.3 LP 8827.1 Mix 60 Delay 2.7 Feedback 24.7 Parallel ON Phase ON Power ON. Instance 3 – HP 410.4 LP 8704.4 Mix 37 Delay 8.6 Feedback 60.6 Parallel ON Phase ON Power ON.
  7. Now let’s add our speaker simulator by dragging a FILTER module from the list and placing it under the last DELAY module. Set its values as follows. LOW CUT – 91.4 HIGH CUT – 9434.4Config-Filter
  8. Add a HIGHSHELF module next, directly under the FILTER module. Set its values to the following: FREQ – 5092.2 Q – 0.3 GAIN – 2.0Config-HIGHSHELF
  9. Add a FOCUS module with a setting of 69.7Config-Focus-1
  10. Add a FOCUS module with a setting of 33.3Config-Focus-2
  11. Add a NORMALISER module with a setting of -4.0Config-normaliser
  12. Finally, add a VISUALISER as the last module. I added two instances here only to show both the Impulse and the Frequency representations of the impulse response. You only should add one instance of the VISUALISER to your chain of modules.Config-Visualiser
  13. Now that we have finished the initial impulse response, let’s save it as a preset with aIR Impulse Rack. Click the “Presets” tab on the right-hand side of the screen. At the bottom of the pane, click “Save Preset” and select a folder of your choice.Save-Preset
  14. Now let’s export the impulse response into a *.wav file so that it can be used within an impulse loader application as an amplifier cabinet. Click the Export button at the top right-hand side of the screen, set your options and click the Export To button to choose a folder to store the *.wav impulse response file. I used standard export values of 44100, Mono and 24 Bit as parameters for my impulse file.Export-IR
  15. Alternatively, instead of using aIR Impulse Rack to handle providing your impulse response to your signal chain, you can use a different impulse loader, like STL Tones’ NAD IR, to act as your amplifier’s speaker cabinet. If you want to use NADIR, uncheck aIR from your FX chain, add STL NADIR and within NADIR, choose the *.wav file you exported. I also changed my routing in NADIR from MONO to DUAL MONO.Config-NADIR


Now that you have made a custom IR from scratch in aIR Impulse Rack, you can tweak the preset you’ve stored to your own liking. There’s no right or wrong and the key is experimentation and finding tones that work great for your equipment and ears.

You can also load existing impulse response files, one or more, to blend and tweak and design your own new impulse. The results are really endless. I hope you found this tutorial useful and if you make any IRs, please send them to me so I can try them out.

If you would like to add to this content to help other folks, pleaseĀ contact meĀ and let me know what you have in mind.