Why IRs shouldn't be overlooked in your quest for tone

Discover a whole new world of tone shaping – and your gear likely already has it on tap

In a world of amp modellers, plugins and travelling lightly – screw lugging a 4x12 cab up and down a narrow venue staircase – IRs have quickly become a riffer’s best friend. But, beyond the buzzword is a piece of gear that shouldn’t be slept on. It isn’t just hype.

While the dials on an amp can greatly impact your guitar tone, and pedals in front of amps, like overdrives and compressors, are also crucial allies in a player’s hunt for the stankiest of tones, IRs can be just as influential. So, what makes them so valuable?

What the hell is an IR?

Standing for impulse response, IRs are essentially a digital snapshot that respond to a sound source – in this case, an electric guitar – in a certain way. Usually, IRs are digital impressions of speaker cabinets, combined with a specific microphone setup – using certain makes and models in certain positions to manipulate the sounds that come blazing out of it.

Beyond that, it also captures the room sound that the original cab and microphones were in. Imagine standing in a cave and shouting; IRs create impressions of the echoes and reverbs of the sound produced, rather than simply reproducing the sound source, to get that ‘in the room’ feel without any physical spaces being needed.

If you’re familiar with amp plugins, you’ll notice that most have a digital cab. On many, IRs can be loaded into these, and there are often presets baked in, offering a whole new world of tonal flavours beyond amp EQs and tone tickling pedals. They can also be loaded into amp modellers, replacing the stock cab simulations, and they’re great for live when going direct into the PA.

Ultimately, it gives players way more options and flexibility, while also adding a greater sense of realism to digital tones.

Why should I care?

Well, you wouldn’t expect to create a killer tone without using the interface of an amp. So we can look at IRs in the same way. Essentially, they are a glorified EQ for your riffs. You’re missing out on a lot of fun if you simply ignore what they can bring to the table.

The thing is, just tweaking the dials on an amp isn’t the only way the final sound can be altered. If you’ve ever played a gig where you plug a tube amp into a house cab, you may have found that your tone, if that cab is different to your usual cab of choice, has a slightly different character. That’s because the cab material, the speaker inside, right down to the microphones pressed against it all shape the final sound just as much as an amp’s EQ.

IRs, then, allow players to fine-tune those characteristics to their whims. In the cab world, there are a lot of nuances that can affect your tone. From the size of the cab – 2x12s can sound more focused because they're coming from a smaller enclosure, but lack girth for some – to the speakers inside, and plenty more.

The microphones used, and where in relation to the speaker they sit, is also a whole world of nuance that, frankly, is over my head. But by messing about with IRs and doing some light reverse engineering work, you can quickly get a basic grasp of which mics speak to you, and which mic positions take your fancy.

Whether they have an open or a closed back, and materials they were built with – MDF is going to sound very different to Tolex, which sits on the higher end of the scale – also hold a lot of sway.

Wait, there’s more…

Another benefit is that it helps you get even more out of your amp sims. Changing the IR can add or take away certain elements, showing more sides to the amps that go through them. They can also provide a cheaper, and easier, way to experiment with different cabs and mic positions to understand how exactly they impact an amp, and can help troubleshoot minor tonal issues, like eliminating some of an amp’s harshness, or adding more boom to the bottom end. And for double tracking, it means the same amp can be used but treated differently for a vastly different sounds.  

Some cheaper, more digital-sounding amp sims can also be saved by IRs. They can be a shot in the arm to a crappy modeller, adding life, likeness, and personality to a tone that would otherwise make your skin crawl.

Gimme the details

Modern Metal Academy is proud to sell its own IR pack for just £5 (approx $7) serving precision-crafted impulse responses for modern and heavy, mix-ready tones. But this isn't about us selling them; we're using them as an example of the details behind the hype.

The pack features eight different IRs, with a Mesa Boogie Rectifier Oversized 4x12, featuring a UK-made Celestion Vintage 30s speaker in its heart. Though that might sound like a vintage cone, it's proven a must-have in modern metal production for its tight low end, rich mids, and bags of clear top-end articulation.

In the capturing process, the cab was paired with an amp that packs oodles of power, headroom, and transparency to ensure that the amp itself doesn't colour the resulting tone. To further aid this, an Audient ASP880 preamp was also used to keep things crystal clear and low-noise.

Below you'll see a list of the microphones and configurations used to create the eight different IRs, and how they can redefine the same cab in a variety of ways. It gets more mileage, and more song-specific nuance out of each and every amp.

Jump here to check the IR pack out.

The best way to understand the IR hype? Give them a go. Load up a plugin (they likely have presets already) or find a free IR pack online if you don’t want to spend any money, and see how the different IRs can reshape a guitar tone without even touching the amp and pedals.

Have tone, will travel

Want to level up your recording and mixing game – and learn how small tone tweaks can help your mix shine? Sign up for Modern Metal Academy’s Recording Masterclass.

Featuring 24 in-depth lessons clocking in over nine hours of tips and exercises, join us as we explore the process of achieving optimal sound quality for your music and demos. Learn in your own time, at your own pace as we analyse mixes and how to optimism them for catching the listener's attention in the modern era by dissecting Monuments' Lavos, which has over four million Spotify streams. 

Head here for more – we’ll see you there.