“I was shocked. That was the exact sound that I had been chasing for years”: Nirvana tone sleuth Aaron Rash solves his epic tone mystery and finds the guitar that Kurt Cobain used for In Utero

Depending on whom you ask, people will either tell you that the world’s greatest detective is Sherlock Holmes or Batman, but maybe YouTuber and Nirvana tone obsessive Aaron Rash should be in the conversation, too.

For years, he has been scouring the archives, searching the internet, interviewing primary witnesses in search of the secrets of Kurt Cobain’s electric guitar tone, his white whale the wiry anarchy of the late Nirvana frontman’s In Utero tone.

And now he says he has finally solved the missing piece of the mystery that has consumed him for so long; he knows the exact make and model of Cobain’s guitar on the album.

He bought one for himself, demoed it, and you can hear the fruits of his labour. Mission accomplished: he has effectively reverse-engineered Cobain’s tone, the cleans and the dirt.

Nirvana - All Apologies (Visualizer) - YouTube

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“I figured out the mystery,” he says in his latest YouTube video, in which all is revealed. “It’s never been about, like, copying Kurt or his tones or anything like that… I’ve just always wanted to figure out what it was, cause it drove me crazy.”

Crazy or dedication? You decide. A bit of context, Rash went so deep into the rabbit hole he event started building his own guitars, replicating those he thought were used during the 1993 sessions for In Utero, where Nirvana tracked an unfeasibly hostile record under the watchful eye of Steve Albini at Pachyderm Studios, in Cannon Falls, Minnesota.

the INSANE amp Kurt Cobain used to record clean tones on in utero - YouTube

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Initially, Rash followed the breadcrumbs online. Some were helpful. Not all. In a Reddit AMA, Albini said it was the Mustang, Jag, Jagstang hybrid, Univox Hi-Flier, and Albini’s own aluminium Veleno guitar, which was used on Very Ape, Heart-Shaped Box and Rape Me.

Rash knew the Jagstang had yet to be made by that point. But he duly spent the next six months of his life building his own Veleno replica, naming it Kurt, making it available for sale.

He also made a Jagstang and a replica of Cobain’s custom-made Ferrington guitar [below] because at this point, well, in for a penny… “I’ve learned everything from just watching YouTube videos,” he told us of his DIY luthiery.

Rash would interview Albini for a deep dive into the recording process. He befriended Cobain’s guitar tech, Earnie Bailey, who helped lead him to one of his first great epiphanies, the guitar amp behind In Utero clean tones, a super-rare 1974 Fender Quad Reverb, but one with Utah speakers – that was the secret sauce. And Bailey helped Rash build the Plexi-style Frankenamp that was also used on the recording. A solid state Randall Commander II combo was the third amp.

Rash found the exact recording microphones, the amps. He then released an In Utero IR Pack so you can access them via your DAW. He did the same for Nevermind.

Rash created those IR packs at Robert Lang Studios in Seattle, where Nirvana tracked their last ever song, You Know You’re Right, in January 1994. Each video found Rash at the edge of another plot-twist, another detail that had “always baffled” him.

One of those, however, was the electric guitar. Many Mustangs later, Rash’s attention was turned to the Univox Hi-Flier, the “pawnshop” guitar Albini referred to in his AMA, and in Rash’s subsequent conversations with the producer before he passed away in May 2024.

“I knew that Kurt didn’t use the Mustang to record In Utero, at least not all the mean stuff with it,” says Rash. “[Albini] said that Kurt mainly used a Hi-Flier to record all of In Utero, that and the Veleno. And I also have a different email that he wrote me as well. He said, ‘I only remember seeing one Hi-Flier. It had the original pickups with the nickel chrome surrounding. It’s possible there were others, but it was mostly that guitar, his Mustang, and the Veleno from memory.’”

Bailey said it might have been a Phase III Hi-Flier. Rash tried that. He tried a modded Hi-Flier with a humbucker. But it wasn’t until he saw a Phase II online with a mahogany neck and bought it out of desperation that he lucked out. He bought it.

I FINALLY found the guitar kurt cobain used to record in utero - YouTube

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Researching while he waited for it to arrive, Rash learned that Cobain did own a mahogany-necked Phase II Hi-Flier. There were pictures of him playing one at the Roseland Ballroom. The electric guitar pickups were stock.

“Literally all the stars aligned,” says Rash. “I know to you guys this sounds stupid, but for me, I’ve been trying to figure this out for so long. So I think you guys know what this means. There was only one thing left to do.”

And that was to play the thing. It sounds exactly like the record. Rash sounds at a loss in this video. He solved the mystery. But who’s to say that, like another great detective, might turn on his heel and ask, “Just one more thing…”

Sappy - YouTube

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Well, as Rash alludes to in this video, there will be another video to tell us more about Phase II Hi-Flier pickups. “Simply put, those Phase II pickups are absolutely wild,” he says. “They’re so weird.” Yes, of course, he has already reverse engineered them.

You can get the Nevermind and In Utero IR Packs at Aaron Rash. And follow this story of obsession and learn more (all!?) about how Cobain got his sound at Rash's YouTube channel.

• Meet Aaron Rash: the YouTuber who's got so close to Kurt Cobain's Nirvana tones he's releasing a guitar and In Utero IR pack to share his discoveries