Impulse response for guitar can be a great way to dial in an authentic and realistic tone without needing the gear which comes with it. Best of all it can be entirely free, so let’s talk impulse response guitar, what it is, and how you can use it to save yourself time, money, and effort in getting the perfect guitar tone in your mix.
What is Impulse Response Guitar
Let’s first identify what is impulse response guitar.
Impulse response, often simply referred to IR for short as it relates to guitar tone is a digital WAV file which encapsulates a guitar setup and everything which goes into it. In other words, impulse response as it relates to guitar is about capturing the character of a setup and room and replicating that on demand.
The elements of said guitar setup captured in an impulse response for guitar include:
Speaker/Cabinet
The speaker/cabinet is what outputs the sound. Depending on their size, power, and make, different speakers have different sonic characteristics which affect the tone of the guitar.
Microphone
Microphones come in all different types with different polar patterns, frequency responses, etc.
As I covered in my comparison of condenser vs dynamic microphones, there are two major different categories for microphones which relate to their sensitivity and how they capture audio.
And as I covered in my overview of the different microphone patterns, there are major differences in the stereo range they can pick up, as well.
While most microphones which are best suited for miking a cabinet are of the dynamic and cardioid variety, there are dozens if not hundreds of notable different microphones which fall into this subset alone which have been used over the decades to record guitar, and each of them has a unique frequency response and way of capturing audio which gives them each a unique sound.
Microphone Placement on the Speaker
Just as important as the cabinet or microphone used to capture it is the placement of said microphone relative to the speaker.
As I covered in my overview on how to mic a guitar cabinet, the placement and distance of the microphone relative to the center of the speaker on the amp plays a huge role in determining both the brightness or warmth of the tone as well as the blend of the amp and room.
The farther the microphone is from the center of the speaker and the amp itself, the warmer/darker and less dry the tone will become, respectively.
Room Acoustics and Reflections
I sort of just referenced this in talking about the blend of the room, but the sound of the room itself will affect the tone, especially if the microphone is farther away from the source that is the amp as I just mentioned.
As an aside and speaking of room acoustics and reflections, impulse response doesn’t exclusively relate to guitar. Reverb is another area where producers rely on/import specific IRs in order to reproduce the sound of a particular room in their own mix without needing to have access to that specific room.
In getting back to impulse response for guitar, the difference in any one of these elements (microphone, placement, room) captured as part of the greater impulse response may be subtle on their own, but combined they have a more notable and unique impact on the guitar’s tone.
The WAV file which represents a specific setup with regards to those elements in an IR can then be applied to amp modeling VSTs in your DAW.
Of course it’s important to mention what ISN’T included in an IR for guitar.
A lot of people who are new to IR for guitar assume they can download an IR file, drop it in their favorite amp modeler, and instantly have THEIR guitar sound like the guitar on their favorite records.
In reality, an IR for guitar is the equivalent of having access to that cabinet, microphone, and even room to a certain extent, just without the amp or any effects to provide the true character of that tone.
Why Use Impulse Response Guitar
People like to capture, share, and use impulse response for guitar because it saves time, money, and allows you to recreate the above described snapshot of those elements/that setup.
This is handy on a personal level if you get a setup you really like and want to save it for future use even after you’ve moved, don’t have access to the same space, don’t feel like recreating the same conditions, etc.
It also means that you don’t need a microphone, an amp, or even a physical space to record – you can simply record DI to simulate the same concept.
Most importantly, impulse response guitar allows you to achieve more realistic, better sounding guitar tones without the hassle.
How to Use Impulse Response Guitar
So how do we use impulse response guitar in our mix on our guitar?
You need a few things to use impulse response guitar files in your mix:
Recorded Guitar Track
Pretty straight forward, but you can’t audition or do anything with an IR guitar wave file without recorded guitar to apply it to.
This should be clean, DI guitar with no other processing on it via pedals/other gear on the in to get the best results, especially if you’re auditioning different IR options.
But yes… have a guitar track.
An IR Guitar WAV File
A simple search will reveal that the community for sharing IR guitar files these days is thriving.
Sites like OverDriven.fr have plenty of great sounding and free IR WAV files you can download without needing to sign up for anything.
You can even create your own IR guitar WAV by running some white noise through/capturing it through your setup.
The white noise essentially captures that sound profile of the amp, microphone, and room, and it’s what is used in the next and final step.
Sweetwater put together a nice quick summary of the process if you want to capture your sound and create your own IR guitar file for future use (or even use for DI recording right now).
An Amp Simulator Which Allows You to Import IR Files
My amp modeler of choice, Guitar Rig Pro has long been compatible with importing custom IR options.
The nice thing about Guitar Rig is that you can import your favorite IR then precede it with any of their dozen or so amplifiers to sculpt your tone of choice, not to mention supplement it with any of the other hundred or so effects.
Blue Cat has a great, simple, and most importantly FREE amp simulator which is conducive with IR files.
Again, it’s a very simple interface; you lock in the cab, mic, and room setup via that IR and you have a number of amp options to work in along with the typical amp equalizer and more settings to dial in your perfect tone.
While impulse response guitar isn’t a silver bullet or all-in-one solution, it can get you part of the way there.
Just do a bit of research to find out the microphone and cabinet on the guitar of your favorite records and check out some of the many corresponding IR files to get yourself well on the way to having more realistic and better sounding recorded guitar.
