Inside the HEDDphone® TWO GT

There are many similarities between cars and headphones: they can vary hugely in price, some are designed from a place of passion and obsession whilst others are deliberately utilitarian and stark.

Many people will follow the same kinds of steps in purchasing a car as they will a pair of headphones. Deep-diving into research and reviews, going for a test drive, discussing with friends, perhaps another test drive before finally making the purchase. You ask yourself, do you want open-back or closed-back? 6.35mm or 3.5mm connectors? Am I listening for work or for pleasure? If you wouldn’t buy a car without establishing the fundamentals, why would you jump into buying headphones without knowing what’s going on inside?

Released in 2024, the HEDDphone® TWO GT is our first ever ‘hifi’ headphone and it has taken its place amongst some of the biggest names in luxury audio. We sat down with HEDD’s Head of R&D, Dmitry Grigoriev, to explore was goes under the hood of the GT, what it's made of, how it came about, and why we think it's one of the best audiophile headphones in the market today.

Dmitry Grigoriev, HEDD's Head of R&D discusses the innovations that went into the HEDDphone® TWO GT.

The (Air Motion Transformer) Driver

The fundamental element at the heart of every HEDD speaker or headphone is our unique AMT driver, which in the case of the HEDDphone® employs a bespoke design not found in any other headphones on the market, and which we dubbed Variable Velocity Transform (VVT). The AMT in the GT is covered with a new multi-layered Kapton polyimide film and pushes sound out of multiple folds as opposed to the traditional single diaphragm design commonly found in many headphones.

This means that the HEDD Air Motion Transformer has four times more diaphragm area than a planar design, and by using VVT to vary the width and depth of the folds, the HEDDphone® TWO GT can accurately replicate frequencies across the audio spectrum from 10Hz-40kHz. Housed in a carbon-fibre and magnesium frame, the open-backed, over-ear design allows the AMT driver to ‘breathe’ and deliver tones with clarity and power.

“All other headphones, for the most part, tune the rest of the headphone rather than the diaphragm. With the HEDDphone® TWO GT we were able to adjust the tuning within the enclosure of the headphone and within the enclosure of the driver itself.”

A diagram explaining how the HEDD Air Motion Transfomer is assembled and how it can improve audio clarity.

Based on decades of improvements, the latest iteration of the HEDDphone® AMT is the most robust yet. The new coating on the folds provides the double benefits of improving the structural strength, and thus enabling a 10% reduction in distortion, whilst also reducing audible ‘crinkling’ and handling noise.

Dmitry Grigoriev: “We asked ourselves: 'How can we process the diaphragm in a different way that can then be industrialized and controlled?' We worked out how to stiffen the folds by using a coating material, applied in different steps, thus increasing the ability of the diaphragm to move as one whilst still keeping the mass low. All other headphones, for the most part, tune the rest of the headphone rather than the diaphragm - the GT was the next step where we had these abilities to adjust the tuning within the enclosure of the headphone and within the enclosure of the driver itself.”

This evolution in the AMT driver, and its reduced distortion, brings a new level of clarity that opens up the details in a wide range of musical genres.

DG: “You want distortion to be as low as possible because it masks other frequencies even though they’re not actually in the original source material. If you have a fundamental tone at 1 kHz, then your distortion might be at 2kHz, and then again at 2.5kHz, etc. If you don't have that distortion then all of that range is clear, all the other musical content can come through - you get all those minute details that are in the recording or the timbre of a musical instrument.”

The impact was immediate.

DG: “Well everything sounded more beautiful obviously!”

Materials and Comfort

If you’re buying a premium listening device you want to be able to wear it for hours on end without straining your neck or ears. The HEDDphone® TWO GT benefits from the construction and component advances made in its predecessor, the HEDDphone® TWO, enabling greater listening comfort over longer periods.

DG: “When it comes to weight, performance and efficiency, we didn't try to change anything on the driver side from the HEDDphone® TWO to the GT. We wanted it to stay within the family, like the TWO just with a different tuning and a more advanced driver.”

The HEDDband technology (patent-pending) in the HEDDphone® TWO and the GT spreads the weight evenly and creates a system that fits each wearer to their personal head shape and preferences. The HEDDband separates the function of holding the headphones together and the form of fitting your head comfortably, meaning no more elasticated bands that lose their strength and lead to loose-fitting earpads. The smart strap system allows parameters like height, width, curvature and even the clamping pressure to be tweaked to personal needs and preferences and set for future use without having to adjust them again.

DG: “A headphone is a very personal thing - you wear it on your head, you touch it, it touches you - so it is very important to have an affection for it. You want to really enjoy the music coming from it, but if the material doesn't feel comfortable, or if it presses too hard, those elements affect your perception and enjoyment of that music.“

The HEDDphone® TWO GT features the same innovative ergonomics as its predecessor with the HEDDband.

“A headphone is a very personal thing - you wear it on your head, you touch it, it touches you - so it is very important to have an affection for it.”

The HEDDband has been further enhanced for the HEDDphone® TWO GT with the standard clamping force (the inherent tension that ‘squeezes’ the ear pads over your ears) reduced to lessen the pressure on the wearer’s head and thus improve wearability over longer periods of time. The development process involved in this proved to be one of the biggest challenges in the GT as the amount of pressure applied to the ear pads significantly influences the volume and tone of the audio signal going into the ear.

DG: “You need to find a balance. If you reduce the clamping force it will definitely improve the longer listening experience, but then you can't go too low because if you don't have enough of a seal around the ear you change the frequency response and lose the bass. We decided to reduce clamping pressure to the point that you actually should be using the tension strap if you want to have it sit firmly on your head.”

With the weight and tension working together to deliver greater comfort, the journey continued on how to further improve the tactile experience of the HEDDphone® TWO GT, this time by exploring multiple different fabrics and materials for the ear pad covers. The choice was made to select two contrasting options for users to select from: lamb’s leather or velour. Given the difference in materials the team worked to ensure that the two were almost identical sonically, allowing the wearer to choose based on their tactile preference rather than the audio performance.

DG: “We changed the ear pad material - but not for tuning purposes, for comfort purposes. I gave us the task to figure out how can we tune these ear pads in a way that they sound actually identical, but have a different cover material? I wanted to give users the opportunity to choose without sacrificing the sound.”

Every element of the GT’s construction was explored to maximise the comfort it could deliver. The foam inside the pads was tested with different clamping force strengths and feedback was recorded on any physical pain points around the wearer’s ears. These points were then factored into the final tension levels to unlock every possible second of enjoyment for the listener.

Tuning

So we know how it works, and how it feels, but the obvious question is: How does it sound? As the growing number of HEDD users across the world will testify there is such a thing as a ‘HEDD sound’, a unique tone that is truthful to the artist's work and creative intentions.

Legendary recording studios including Hansa in Germany and Miraval in France; groundbreaking artists like Q-Tip and DJ Jazzy Jeff; Grammy-nominated producers including Alissia and Tokimonsta; and blockbuster media composers like Haushka and Hildur Guðnadóttir all trust HEDD speakers and headphones, and the AMT driver, for their creative work. Decades of heritage in the studio world have built a sonic imprint that is perfect for crafting and sculpting a song, providing clarity to hear both the details to be enjoyed and the issues to be addressed.

With the HEDDphone® TWO GT there was a recognition that many users who aren’t sound engineers or music producers may also want the benefits of the speed and precision of the ‘HEDD sound’ but in a slightly less analytical way and with more of a high fidelity tone that is aimed at listening pleasure instead of sonic linearity.

DG: “What happens with an analytical headphone is that it shows you all of the faults within a song. But when you're relaxing and want to enjoy music you don't want to hear its faults, you know that they exist, but you don't want to be constantly reminded of them.”

With that in mind the R&D team began to dig into how to create a new tuning that stayed true to the ethos of HEDD but also allowed listeners to fully lose themselves in their favorite music. An extensive quality control process was put into place with input sought internally and externally to find the tuning sweet spot for HEDD's first hifi headphone.

DG: “We went through a lot of listening tests and A-B comparisons between different tunings with a focus group inside the company. We're all in the audio world professionally in different aspects - one of our QC team members does live mixing; (Dr.) Freddy (Knop) obviously has a PhD; I design speakers and headphones, etc. But we then also got input from the outside as well, that helped us get out of a certain tunnel vision. You need to be able to accept feedback from the outside world and not just decide on your own because you ‘know better’ - you need to think outside of your own preferences.”

“An analytical headphone shows you all of the faults within a song. But when you're relaxing and want to enjoy music you don't want to hear its faults, you know that they exist, but you don't want to be constantly reminded of them.”

Frequency graphs comparing the HEDDphone® TWO and GT.

The combination of the AMT’s new coating, the materials and density of the ear pads and the relaxed clamping force give the HEDDphone® TWO GT a tone that puts the emphasis on the lows and highs instead of the mids.

But when you have options, you also have to have decisions, and the team didn’t want to push the sonics too far.

DG: “Why should I falsify the content? The goal behind HEDD is a natural sound, ‘true to source’ should be the target. But you can also interpret things in a different way, a different perspective on the musical content, and you can adjust the tuning in that way without falsifying.”

Cables & Accessories

All of these tweaks and technological developments mean that the HEDDphone® TWO GT is refined and ready to help listeners immerse themselves in their favorite music, and each unit comes complete with a multitude of ways to connect to a variety of playback devices. Another upgrade between the HEDDphone® TWO and GT is a hand-braided and nylon-woven, 4-core 5N SPC high-grade cable as standard with an optional high-end, 8-core LC OFC, GTC cable available separately for those who care about every aspect of their listening experience.

To connect to your chosen source, the HEDDphone® TWO GT also includes a 1.6m unbalanced headphone cable with a 6.35mm termination; an unbalanced 6.35mm-3.5mm adapter; a 1.6m balanced cable with 4.4mm termination; and a balanced 4.44mm to XLR 4-pin adapter. With so many cables, plugs and adaptors there really is nothing to stop you from rediscovering your most cherished music as soon as your HEDDphone® TWO GT arrives.

Click here to order the HEDDphone® TWO GT directly or if you want to arrange a test drive listening session and hear what it can do for yourself find a local stockist.

Photo credits: Felix Zimmerman.