The surprising secret behind Kurt Cobain’s guitar tone on Nirvana’s In Utero has been discovered, 30 years on from its release

2023 marks 30 years of Nirvana’s In Utero, and ever since it was released guitarists have obsessed over how to best replicate Kurt Cobain’s incendiary, unsanitary electric guitar tones. But the secret behind Cobain’s tone might finally have been revealed by a YouTuber with a serious In Utero obsession.

Aaron Rash has made a series of videos about Nirvana but in this latest video, in which he concludes that the secret behind Cobain’s In Utero tone is not just in finding a vintage Fender Quad Reverb – in itself quite a feat, for the company only made them for four years or so – but finding a Quad loaded with what he describes as one of the rarest speakers in the world.

Rash admits that it might be “a little weird” that every video he makes is about Nirvana or Kurt Cobain but he promises he is not obsessed. He is not going to grow his hair out, dye it blond and wear oval-framed Christian Roth sunglasses. It is In Utero that fascinates him. Savage, untamed, wild and electric and yet somehow organic, as though Cobain exhumed those tones from the dirt.

While it would seem as though we already have everything we need to understand Cobain’s In Utero tone, and thus everything required to replicate it, it’s always out of reach. It is remarkable we have got this far, with In Utero long since immortalized in the pop-cultural firmament, that the album still holds such mystery. It’s like the Zodiac Killer of guitar tones. Rash, for his part, is our Robert Graysmith.

kurt cobains fender quad reverb used to record in utero - YouTube

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We know, thanks to Cobain’s guitar tech, Ernie Bailey, in conversation with Reverb in 2014, that Cobain favored his Competition Blue Mustang, a Jaguar and producer Steve Albini’s aluminum Veleno for the sessions. 

Rash is aware of this, and even built a replica of the Veleno in search of the Holy Grail. We know there was a Quad Reverb. What Rash has discovered, however, from A/Bing different Quads, is that the speakers don’t just matter – the speaker is everything.

“Fender was on this speaker train way before anybody else was,” he says. “They understood. They knew that, ‘Hey, different speaker, different tone.’ You can use the same amp head and still get a lot of different tones with different speakers.”

Which is why just getting any old Quad Reverb won’t necessarily get you the exact same tone – even accounting for the usual caveats that tone is in the fingers, a consequence of how we as individuals touch the guitar, the pressure we exert on the strings, and so forth.

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As Rash tells it, Bailey turned Cobain on to the Quad Reverb and they picked one up from a listing in Tacoma, Washington. Up to ’74, Quad Reverbs packed Oxford speakers, with blue stickers on the back. Rash says there was the one year where things changed for the Quad; Fender reverted to Utah speakers, with the orange stickers on the back. And this, 30 years on, is the secret sauce.

“That’s really the missing ingredient to the sound of In Utero, this Utah speaker,” says Rash. 

To prove just how critical these speakers are on the tone – not the tone stack, not the tubes, not the guitar amp per se – Rash runs the signal from his Randall combo out through the Utah speakers, and it is uncannily accurate.

“What is really crazy about this speaker, like, I thought it was the Filter Matrix [from the Electro-Harmonix Electric Mistress], and it actually wasn’t,” says Rash. “It’s just these speakers. They have like a natural Filter Matrix sound built-in. They just sound like that.”

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So there you have it. Forget the amp. After all, the schematics for the Quad Reverb and the Twin are the same. It’s the speakers. Maybe someone should make an IR of these Utah speakers. 

Oh, Rash is already on it, and through a Tech 21 SansAmp pedal and a home captured impulse response, it already sounds pretty good. His next step is to take the Quad to a studio, mic it like In Utero, and make “an exact digital copy” of the tone. Will it work?

Technically, yes. But as Bailey said to Reverb in 2014, in the grand scheme of things, the gear didn’t matter much to Nirvana.

“They were a rock band that used both good and bad equipment, but in the end, it was the songwriting that made them important,” he said.

You can follow Aaron Rash on YouTube, and check out his In Utero Quad Reverb speaker conclusions above.