Why are James Hetfield and Kirk Hammett Using Axe-Fx and Not Other Amp Modelers? Metallica’s Guitar Tech Explains

For years now, Metallica’s Kirk Hammett and James Hetfield have been using Fractal Audio’s Axe-Fx digital amp modelers. This was a major change for a classic metal band and it’s been one of the most interesting shifts within the guitar sphere. However, with so many different choices for digital modelers, and profilers, why did Metallica choose Axe-Fx of all things? Well, according to the band’s guitar tech Chad Zaemisch, there are a few important reasons.

This shift happened around a decade ago and according to what Chad said in an interview with RJM Music Technology, a few of the important features of Axe-Fx were detrimental. Asked about why they chose that over Helix, Kemper, or Neural DSP, which also got popular during the 2010s, Chad replied:

“Back when we were going to make a run at the digital realm, the Axe-Fx was really the only one that could have two amps at the same time going because that’s what we were doing with our analog gear — we had the Mesa Boogie sound, and the Diesel sound.”

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While it may seem straightforward, some of Axe-Fx’s specific advanced traits helped them make this decision, particularly the time aligning between two amplifier models:

“In order to have them stay synched exactly up the whole time, you’d have to have them in the same unit, and the Fractal does a really great job of time-aligning everything before it comes out as well. You can even kind of fudge things around a little bit, but that phase between those two amps is so unbelievably important.”

Sure, it’s all measured in milliseconds. But when it comes to the guitar tone, milliseconds mean a world of difference for phase. Chad continued:

“I mean, you can move a couple of milliseconds on one waveform or the other, and it just completely changes the sound. And it had two different main outputs — it has four of course, but it’s got two of the main XLR outputs.”

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“So I could do stereo out, one side being the Boogie, one side being the Diesel, so that the front-of-house guys monitoring and everybody else had those individually.”

“And then I have basically a stereo clean sound, which is still a JC-120. That’s in a second unit, but it came down to the amount of ins and outs of it, and what the unit was capable of.”

However, as the band’s longtime tech explains, he wasn’t initially all that fond of Axe-Fx. Mainly because it felt a bit tricky to set up:

“I had tried the Fractal for a minute, and I don’t know what it’s like now, but at the time, it was very difficult to navigate — like the file structure and all of that kind of thing.”

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But then they got the help from Matt Picone, one of Fractal Audio’s most important people:

“When Matt Picone came out and helped us, it was just like, ‘Ah!’ [relieved sigh] This is the only thing that, at the time, was going to even do it.”

“It allowed us to use some of our own sounds — I have the cab blocks in there, samples that I have made from our giant ISO boxes where we used to have a 4 x 12″ in there, and an AT mic. So it was the only thing capable at the time, and I’m glad we’ve stuck with it.”

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Despite admitting that other brands also have great stuff, Chad concluded by saying that Fractal was the way to go for James and Kirk:

“I know the other companies do great stuff, but this was like the only thing that was going to do it — it was the Fractal.”

In another section of the interview, Chad also discussed some of the details on how the effects switching works for James Hetfield. After all, Metallica often have very specific stage setups, and you never see James doing any pedal or foot controller tap dancing. Asked about how this works, all because the interviewer saw the Mastermind GT unit behind him, which is an advanced MIDI controller, Chad responded:

“We do all this switching for the guys off-stage because James has got 14 mic positions on this, so there’s no way he’s ever going to make it to a pedal. And it’s been so long now that he doesn’t want to have to think about that stuff, which is singing, trying to play guitar, and running around the stage all at the same time.”

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As Zaemisch also adds, James practically doesn’t have to think about anything on stage other than playing his songs. All the switching is done by techs backstage:

“He doesn’t need to be thinking about hitting the right patch at the right time. So that’s what all of us techs do for the band members off-stage — do that stuff for them. And so it means you gotta pay attention to what you’re doing, and you have to know the songs.”

Photo: Kreepin Deth (Kirk Hammett and James Hetfield live in London 24 October 2017)


  • David Slavkovic

    David always planned for music to be nothing more than a hobby. However, after a short career as an agricultural engineer he ended up news editor at KillerGuitarRigs, senior editor at Ultimate-Guitar.com, as well as a freelance contributor to online magazines such as GuitaristNextdoor.