Interview: HEAVYS CTO Axel Grell Discusses Crafting Headphones Specifically for Metalheads, Ensuring Optimal Sound for Iconic Bands

by John Hill at The Pit

There aren’t many people on earth who know more about sound than HEAVYS CTO Axel Grell. With over 30 years in the industry, Grell set the standard for what a great pair of headphones should deliver when it comes to sound. He’s designed some of the most important headsets for listeners, including the perennially iconic Sennheiser 650s. So, when we heard that he was the man to help guide the audio direction of the brand, we perked up immediately.

Those years of experience become immediately recognizable when you put on a pair of HEAVYS for the first time. The sound quality is apparent immediately, upon first listening I threw several albums to take them for a spin. The low drones of diSEMBOWELMENT’s one album Opus Transcendence Into the Peripheral kicked my ass in the same way I remember it doing so as a kid. Meanwhile, the recent record The Sin of Human Frailty by END feels like it was built for the pair, from the massive riffs at the foreground of the record to the intricate electronic elements the band added into the back of the mix.



There were moments on albums I felt like I memorized back to front that revealed new aural details on these listens. Hearing Sergio Vega’s bass grooves on Deftones’ “Swerve City” added an entirely new dimension to the song that I hadn’t experienced prior. It was like taking a sci-fi pill that let me rehear those records for the first time in my life again, and enjoy everything all over.

Grell’s pedigree for sound became immediately clear on this listen, and it truly felt like a labor of love for all fans of heavy music. We spoke to Grell about designing the headphones, and what goes into specifically engineering a pair for this genre of music. You can check out our full thoughts in our review here.

This interview has been edited and condensed for clarity. 

THE PIT: So I’ve been using the HEAVYS for a couple of weeks now. I’ve been paying attention to the heavy metal space for probably ten or so years. It seems like anytime enters the space with a product, it’s usually white-labeled junk. But even just holding these, these are premium off the bat. Can you talk a little bit about the design?
Axel Grell: You know, I’ve done a lot of headphones. I was at Sennheiser for 27 years, and when you’ve done that and other headphones, you get an idea for not only the sound quality but the build quality of a product as well. So we want to get the best, what’s possible for the money, soundwise and build quality-wise. Our quality requirements are very high.

The other thing is, [engineering] for metal music, some metal music is very, very complex. A lot of things are going on at the same time, and when the recording is done in the right way, you can hear all the details on everything. When the quality [of headphones] are bad, it’s all just one basic flat sound and you can’t differentiate the nuances. So when you look inside of the headphones, you can see, we have two front speakers and we have two woofers inside. So this is very unusual. So the two woofers here and here, and little microphones for the noise canceling.

When you’re listening to music using speakers, and when you’re listening to live music, the band is playing in front of you on the stage. The mixing for music is mainly made for speakers in front of you or whatever is in front of you. The reason why I put the tweeters in front very close to the skin so that the sound moves from the front to the pinnae [the visible portion of the outer ear]. It’s reflected as it is when you’re listening to natural sound sources in front of you. The high frequencies are going to the pinnae and are reflected from the pinnae into the ear canal. That gives a very, very individual pattern, as individual as your fingerprint.

I’m curious, in the development of the headphones, were there any specific bands that the team went back to constantly? Like, “This needs to sound incredible on the headphones or else.”
I was listening to a lot of different music styles, but for these headphones, I listened to a lot of Slipknot albums. [Laughs] But it’s not that specific, it must work with everything. So when you’re listening to a Metallica intro for example, which are very nice and soft and very well recorded, you should get goosebumps. But when you’re listening to speed metal where there’s a lot of things happening, you should get everything in there.

When you’re working on a new pair of headphones, or even when you get a pair that isn’t your own, is there a song that’s your first spin to test what the capabilities are?
It’s usually a lot of different things. But one thing when I test headphones, I just need to listen to the noise at the beginning of this analog recording. It’s a guitar player, Peter Green off the album “In the Skies,” and the song is “Slabo Day” When I just hear the noise in the beginning, I know. I’ve listened to it so often that I don’t need to hear the full song, I just need to hear the noise.

When I was younger, I think I would definitely torch my ears just blasting music as loud as possible. Obviously, heavy metal is a genre somewhat built on loudness. How do you find a balance between being able to get listeners to get a really loud sound without killing their hearing or negatively affecting how the music sounds?
I think metal music definitely needs to be heard loud. So, when you go to concerts, you should protect your hearing with some earplugs. When your ears are damaged, you can’t repair them so it’s really important to protect your hearing. I remember going to a Gary Moore concert, with earplugs and it was too loud. The mix was very annoying, so I needed to move out.

But when you’re listening with the HEAVYS, it’s loud but it’s loud in the right frequency ranges so that it moves you emotionally and it’s not cutting in your ears. Human hearing is most sensitive between 2.8 kilohertz and 4 kilohertz, and when there’s too much sound in that range it damages your hearing very fast. So we didn’t put too much in that range, it’s still balanced. As a listener I listen loud normally. When you’re listening to it for one hour at full speed on maximum volume, you don’t hear beeping tones or something like that, like you would at a loud concert. So it’s below that threshold. 


Shop Best Headphones for Metal Heavys Headphones 

Shop our Custom Designs of  Snap-On Shells

Back to blog