Quick Guide to Impulse Loaders
In order to help you get started with using Impulse Responses (IR:s) in this post we make an overview of what IR:s are, how they are used and we list the available IR loaders.
What is an impulse response?
Starting from the very beginning an impulse response (IR) is the output of a system when presented by a short input (the impulse). So if you feed a known, controlled sound into a system and measure the resulting output, you get a way of describing the characteristics of what that system does to the input signal. This can be used for many things, macroeconomists use IRs to estimate what happens with the economy when some external event happens, it is used to capture the characteristics of a room (used in convolution reverbs), and finally getting to the point – it can be used to measure what a guitar cab does to the signal it gets from the amplifier.
When used this way the impulse response usually captures the impact the guitar cabinet, speaker and microphone have on the sound. So if you insert an impulse response in your signal chain you can actually simulate a mic-ed up guitar cabinet!
This can be incredibly useful since it allows you to listen to how your amp sim would sound through different gear that you don’t own yourself, or can’t afford to buy. Want to hear what your amp sim with a Marshall 4×12 cabinet sounds like, mic’d up with a Shure SM57? Simply load an IR with that combination of cabinet and mic. You want to try a vintage 1×12 with a Royer121 mic? Simply drop in another IR and you can hear what that sounds like!
When you are recording a physical guitar cabinet with a microphone you can get a great range of tones depending on what speaker is in the cabinet, which microphone you use and where you place your microphone. Most IR libraries give you a number (sometimes a huge number) of IR files with different microphones and mic placements. So to be able to use IR:s in the best way, you should know a bit about how different microphones and mic placements affects the tone. This is a science all in itself, but check this Sweetwater article for some starting tips.
There’s a number of developers of IRs out there and using IRs you can get an almost infinite number of variations to your guitar tone.
How to use it
In order to use your IR files on your computer you need an Impulse Loader. Think of this as a player for your IR files. It is inserted in your signal chain after your amp sim software.
Many plugins have built in cabinet sections, but not all allow you to load your own IRs. If your amp sim has a built in cabinet section you would have to disable that before using an external impulse loader. A couple of reasons for using an external impulse loader could be that the amp sim has a weak cabinet section, none at all, or just that using an IR loader gives you a bigger selection of IRs to use, therefore a greater choice of tones are obtainable.
Note: remember to disable the built in cabinet section of your amp sim before using an IR loader – if not you would be running your signal to two cabinets which likely will not give you the tone you’re looking for…
Next up is a list of available IR loaders that you can use. A tip would be to try out a few, perhaps get to know the simpler freeware offerings first, stick with one for a while to fully understand how it works and then branch out to more complex offerings once you are completely sure of what you are doing.
List of IR loaders
Freeware
AURORA DSP FENRIR
Aurora DSP is one of the newer developers that has made some impact recently with their excellent Mammoth and Rhino amp sims. FenrIR is a free impulse response loader that allows you to load two IRs and has a animated UI that effectively let’s you align the peaks of the two. Another nice feature is that it let’s you export your mixed IR.
Lancaster Audio Pulse
Pulse is another free loader that is offered from Lancaster Audio. It is basically a rebranded version of Ignite’s Nadir 1.0. It’s a simple loader that offers a solid set of features. But since it’s based on an old version of Nadir, most users would probably be better off by using Nadir 2.0. Still – if you want a simple impulse loader that’s got all the necessary features but nothing more Pulse might be worth trying out.
STL TONES / IGNITE AMPS – NADIR 2.0
Nadir 2.0 is probably the most commonly used IR loader and for a good reason. NadIR allows the user to load two IRs. It let’s the user blend these in mono or pan them L/R when used in stereo mode. Apart from the standard controls like high/lowpass filers and phase inversion it also features a resonance control that simulates power-amp imdedance. And there’s also a room control to add a bit of built-in reverb. The delay control let’s the user match up the phase between two loaded IR:s, but without any visual cues it’s not an easy task.
This is a high quality IR loader for the price of nothing. Many users start with IR:s using Nadir and quite a few find they never need anything else. If you’re new to using IRs this would be a great place to start.
Payware
3 SIGMA AUDIO – IMPULSIVE
The Impulsive loader was originally designed by TSE Audio and is very similar to the cabinet loader that exists only inside the TSE X50 plugin. Impulsive has a nice user interface and has a good way to navigate through your IR folders (which over time can become quite large).
Included in the price are some of 3SA’s own impulses, including a 412 a 212 and 810 for the bassist out there.
AUDIO ASSAULT AIR
Audio Assault are well-known for offering very good value-for-money in their amp sims. With the aIR Impulse Rack they have introduced an IR loader done a bit differently – aIR is a modular IR loader that has 10 processing modules, and you can load as many modules as you like into a rack. Each of the modules include a loader, delay, volume, filters and more to let you shape your IR:s any way you want. There’s also a visualizer to let you see the result of your processing. In the end you can export your result as a new IR file.
The modular approach is a nice but adds complexity to the workflow. But if you need the control you get from this – aIR might be the loader for you.
Celestion SpeakerMix Pro
Celetion has made speakers for guitar cabs since the 1950s and probably need no introduction. They have now joined the IR game, releasing high quality IRs which capture the sound of their speakers. And with SpeakerMix Pro they also have a loader for their IRs. It uses a new format called Dynamic Speaker Responses (DSR) but also loads third party IRs. Up to six IRs can be loaded. Included are also room responses for reverb and built in modeling of the dynamic coupling between amp and speaker.
Included in the package are 10 DSRs from Celestion and more can be bought in their shop.
FORWARD AUDIO: FAIRMAGEDDON
FaIRmageddon is branded as a “Guitar Cabinet Impulse Response Designer Plug-in”. The feature list is long and features things like being able to blend seamlessly between different IRs. You can also manipulate your IRs with a number of sound design features. There is also a “tone-match” feature where FaIRmageddon tries to match your IR to the sound of a guitar signal you feed it.
Included are also a number of impulse responses from Valhallir.at . All in all a pretty unique and interesting product.
Nembrini – IR LOADER
The new IR Loader from Nembrini features 3 IR loading slots, and comes with a great number of IRs built-in to get you started. It also allows you to load your own favourite IRs and manipulate them with tools like the 6 band parametric equalizer, the custom desk compressor, and also a power amp sim to breath a bit of magic and life into all your IRs.
REDWIREZ – MIXIR3
Redwirez is a name that has been in the game for a very long time. The new and improved MixIR3 can load any regular impulse response file from any developer including the newly remastered Redwirez packs.
The main new feature involves the brand new Redwirez modules that lets you adjust mike and mic position in a 3D way. MixIR3 comes with an included Marshall 4×12 to get you started. You can buy more modules from Redwirez (all the new BIGbox IR:s contains modules for MixIR3). Users can load up to 64 files and there’s a number of great onboard processing tools to further shape the cabs and help them fit into a mix.
If you like the Redwirez IRs and want a visual way of working this might be for you.
STL TONES/IGNITE – LIBRA
The Libra is one of the heavyweights of the IR loader world. It’s full featured and allows you to load up to 8 IR:s at one time. A unique feature for the Libra is the “cartesian mixer” which is a visual interface that lets you blend the loaded IR:s in a seamless way. When you get the sound you want Libra let’s you save your blended IR:s.
It comes with 10 included IR:s captured by STL Tones. But if you don’t have much of an IR library you likely won’t get as much use for Libra. Also for a beginner learning the basics, mixing between 8 IR:s probably just adds to making the learning curve steeper.
UGRITONE – TRVE CAB
Trve Cab lets you load up to 8 IRs, either of their own or from other developers. Instead of mic positioning, it uses a mixer-style interface to let you blend them all. Ugritone’s IRs are designed so you get fixed positions based on the recording experience of the developers, which is a nice approach that let’s you get some excellent tones quickly. A freebie pack is included and you can purchase additional IR packs from Ugritone’s website.
Ugritone are a company that is focused on a ‘no nonsense’ approach. They aim towards helping you in your productions of various genres of Heavy Metal & Rock. The Trve Cab reflects the company’s ethos, and has a flair for those styles in the plugin’s unique GUI.
Two Notes – Torpedo Wall Of Sound
The Torpedo Wall Of Sound (WoS) plugin is an impulse response loader designed to work on its own or along with the Two-Notes hardware. Users can either load their own third party libraries or the specially made cab packs designed to only work with WoS. Two Notes offer over 400 of their custom cab packs (called DynIR).
WoS also has a huge list of extra features to help shape and customize your tone, including power amp emulations that can be useful if you run an amp sim without power amp like Mercuriall SS-11X or any of the amps from Nalex. The plugin also features a “simulation mode” as well as an “arcade mode”. Most users will probably prefer the former.
Note: Other similar products
ML Sound Lab’s MIKKO plugin and MCabinet from Melda Productions are not impulse response loaders but instead virtual (algorithmic) cabinet simulators. They are quite incredible really and well worth trying out.
Softube’s Celestion Speaker Shaper is a ‘speaker shaper’ but not an IR loader… it comes pre-loaded with 11 officially endorsed Celestion speaker models, and 8 microphone models to choose, plus many interesting ways of tweaking and shaping your output. Available as both a plugin and as an add on to Softube’s Amproom.
There’s also a number of discontiued products like LePou’s LeCab, Kazrog’s popular Recabinet plugins and a number of other loaders. These are still more than effective if you already own them.