Mixing With Impulse Responses

Hello, friends and strangers! I’m Jake Duffie, from The Underground Alliance, and I’ve been doing this audio thing seriously for about three years now. Though I am still quite fresh to the profession, I’ve spent my whole life toying with the software as a hobby, and spent a year at Recording Arts Canada to get a solid baseline knowledge of recording standards, and techniques.

Now that I’ve introduced myself, I’m going to talk a little bit about Impulse Responses. An impulse response, or “IR” is a short audio file (about 0.5-2 seconds) that captures the audio effect of a room, reverb, cab/mic simulation, or any number of audio modifying clips, meant to have a primary sound being pushed through it.

As soon as I learned how to use an IR, it replaced nearly half of my plugins. One of the biggest boons to these files over algorithmic FX VSTs, is the tiny amount of CPU power it takes to run them by comparison. That being said, this means that the effect is static, and hits the audio the same way, at all times. This can be an advantage for consistency, but you can lose a little musicality in the process.

The first time I had founding myself needing to use an IR, it was to simulate a mic/cab after a free guitar amp VST. While the use of IRs for a cab sims has it’s disadvantages, it got me to look into all the other uses of simple wav files loaded in as an effect.

The biggest advantage I have found so far, is the ability to utilize the many captured IRs that are widely available around the web of expensive vintage gear. The Lexicon 480L IRs find a place on every session I’ve worked on since obtaining them.

LOADING IRs

There are a variety of VSTs that are capable of loading IRs, but I’ll be using ReaVerb for this example. Download links can be found at the bottom. I would also recomend NadIR, for low latency tracking with amp sims.

Though I will be using REAPER, this steps will work in nearly every other Daw. ReaVerb can be downloaded within the free ReaPlugs suite by Cockos, if you are not using REAPER yourself. You will also need a file to use as the IR, so I’ll use one of the files from the Lexicon 480L unit, which can also be found at the bottom of this article.

We will be adding reverb to a track, so add the ReaVerb FX to the track that could use a little more space and sustain. If you are loading an amp sim, you would want the wet knob all the way up and the dry completely off, but with this being a reverb, you will want the dry at unity (0.0dB), and wet at about (-30.0dB) to start. Press the “Add” button, within the VST gui. choose the “File” option, and you will be brought to the Windows Explorer/Mac Finder to locate your audio file. I will choose the Silver Plate

At this point, your work is roughly complete. You have your audio file playing at full volume, with a version of the same audio being run through the IR of your choice at (-30.0bB). Set the wet to taste, and that’s it!