“You can now have the sound of your favorite Nirvana record all in the computer without touching a single physical amp”: Kurt Cobain tone guru Aaron Rash releases The Utero Sessions IR Pack

Some time ago, Nirvana superfan Aaron Rash fell down a rabbit hole chasing Kurt Cobain’s wiry and feral In Utero electric guitar tone, and after two years of obsessive development Rash has unveiled an IR pack that allows you to recreate Cobain’s tone at home.

The Utero Sessions IR pack is a labour of love and no small amount of investment on Rash’s part. Over the past years, he has gone through all kinds of amps trying to find the right one that sounds just like the record.

“I have bought and sold probably seven different Quad Reverbs to find the the perfect sounding one, because – news flash – they don’t all sound the same, even with the same speakers,” he says. “They really vary all over the place.”

Finding the right speakers turned into an epic quest in itself. Speaking to MusicRadar in January, Rash said it was less about which guitar amp was used and more about the speakers, especially when it came to articulating the right texture of distortion.

“Every amp is different and it's going to affect the tone,” Rash said. “But I found speakers make the most difference, especially for distortion tones – it’s like night and day. And I’ve always thought about it like this: if you take white noise and you run it through a speaker, every speaker is going to have its own profile – they’re all going to have their own sonic profiles. Distortion is just like white noise really – if you hear it without going through a speaker, it just sounds like trash… The speaker is really important.”

What you get in The Utero Sessions is a very specific speaker, one that was made by Utah specifically for Quad Reverb but rarely found. Not many were made. “With its undersized magnets, and 16 ohm voice coil, nothing else sounds quite like it,” says Rash.

Creating the pack, Rash used the exact same 1940s ribbon mics, with the secret sauce being the room in which the IRs were created. He also used the knowledge from Kurt Cobain’s guitar tech, Earnie Bailey, and In Utero’s producer, the late Steve Albini, who become a mentor for Rash in this quest. When there was much debate about whether there was a Boss DS-1 distortion pedal or a DS-2, Albini confirmed it was the former – and more than that, that Cobain would keep a bunch of them around. 

the in utero I.R pack is FINALLY HERE! - YouTube

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If you have followed Rash on his YouTube channel, you will know that no stone has been left unturned. He once even made a replica of Albini’s aluminium Veleno guitar that Cobain used to track Heart-Shaped Box and Very Ape.  

“I sourced all the original microphones that were used on the record, preamps… literally everything, and the amount of money that I’ve spent has got to be astronomical,” he says. “I honestly don’t want to know how much I’ve spent to do this, but it’s done! And I am so happy to share it with you guys.”

To use the pack, you will need a software amp guitar plugin. Rash recommends the Softube Vintage Amp Room, but says any sort of Fender Twin Reverb-style of amp pack would work. “The amp’s not really important,” he says. “What’s important is the IR pack.”

Rash offers a step-by-step guide to how to upload the IRs onto your software and get The Utero Sessions up and running. He uses Fractal’s Cab Lab IR loader for the job. 

the nirvana "bleach" amp kurt cobain used (with jack endino) - YouTube

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Watch the video above for an idea of how it sounds and how it works. Head over to Aaron Rash to order. Priced $49.99, The Utero Sessions is available now. Read MusicRadar's interview with Aaron Rash here, where he takes us back to the start of this tone hunt, retracing the steps that brought him here.