HEDD Audio HEDDphone TWO GT

Design & Construction of the HEDDphone TWO GT

The new HEDDphone TWO GT is based on the still available HEDDphone TWO. At its heart is the Air Motion Transformer (AMT), which company founder Klaus Heinz has refined over the decades, building on Oskar Heil’s invention from the 1970s.

This driver of the HEDDphone TWO GT is special. Instead of a one-to-one piston-like drive with a voice coil, a powerful magnet drives a lightweight, folded Kapton film with conductive tracks. The result is a 3x increase in surface area and much higher efficiency with very low distortion. In its original form as a tweeter, the AMT has long been an established alternative to other types of driver.

In HEDDphone models from 2020, these AMT drivers are full-range, patent-pending types that cover the entire frequency spectrum. By design, the HEDDphone TWO GT is quite large and heavy at 550 grams – inevitable given the powerful magnets and the size of the drivers. As a result, the headphones are generously padded and feature an ingenious, patent-pending dual headband system (HEDDband). While the design is a matter of taste, the build quality is definitely excellent and robust.

This is reflected in the generous five-year warranty. The package includes woven, fabric-sheathed balanced and unbalanced cables that connect to 3.5mm TRS plugs that are angled forward on the earpads to allow them to run smoothly along the torso. Adapters for 6.3mm jacks and the four-pin XLR format are also included.

New features of the HEDDphone TWO GT

According to the manufacturer, the HEDDphone TWO GT is aimed more at audiophiles than professional audio work, although this review unit is undeniably suitable for the latter. The tuning is said to be warmer and more pleasant than that of its sibling, the HEDDphone TWO, which is primarily aimed at the pro audio segment. According to HEDD, this particular sound tuning was largely influenced by feedback from the Head-Fi community and extensive listening sessions conducted by chief developer Dmitry Grigoriev and company founder Dr Frederik Knop.

The driver’s damping has been redesigned and now features a new coating of Kapton polyimide film to direct sound in the desired direction and further minimise distortion. At the same time, of course, the remarkable detail and transparency for which the design is renowned has not been sacrificed. According to the manufacturer, the HEDDphone TWO GT provides an extra boost in the bass range for a fuller sound, along with a slight emphasis in the higher frequencies for added transparency.

The HEDDphone TWO GT’s comfort has also been improved and the design updated. In addition to visual refinements and a more decorative logo, upgraded cables (4-core 5N SPC) are now used, which can be replaced if necessary. The product also comes with two sets of ear pads specifically designed to match the drivers. The leather and velour versions are said to be identical in sound, differing only in comfort. The GT suffix, familiar from the automotive sector, is therefore entirely appropriate.

The HEDDphone TWO GT in practice

Because of its weight and size, the padding and headband design of the HEDDphone TWO GT is a crucial issue. The ear cushions are mounted on a carbon fibre bracket that allows them to swivel and tilt, and they are also slightly angled inwards. The HEDDband really does allow the fit and clamping force to be varied independently. As a result, this tester can be worn comfortably for long periods of time. However, the design is not intended for rapid or abrupt movements, but rather for listening while sitting on a couch or in an armchair.

The wearing comfort of the HEDDphone TWO GT is therefore good, but predictably less ‘light’ than a Sennheiser HD 800 S, for example. For the following listening tests, I used the sheepskin ear pads, which tend to generate less heat than the synthetic leather versions.

Sound of the HEDDphone TWO GT

In general, it makes sense to use a high quality headphone amplifier to drive such sophisticated headphones. HEDD recommends an output of 1 watt. Unlike some competitors, such as Stax, a dedicated electrostatic amplifier is not required. Our reference amplifier, the RME ADI-2 Pro, handled these headphones with ease. Even at low volumes the headphones showed remarkable resolution. With the DAP Shanling M3X, on the other hand, I had to turn up the volume a bit – even when using the balanced output – to get it up to speed.

The level of detail provided by the Air Motion Transformer is immense. Nuances and transients allow for a precise reproduction of the arrangement, the stereo panorama and the spatial environment. At the same time you get a microscopic insight into the dynamics and timing of the material. The listening experience is truly analytical. At the same time, the HEDDphone TWO GT delivers enough warmth and musicality to make listening an immense pleasure.

Classical orchestral recordings and jazz are convincingly reproduced with first-class resolution, dynamics and authenticity. The reference track ‘Celestial Echo’ by Boris Blank and Malia reveals a deep insight into the spatial electronic production, where the voice is beautifully placed – an impressive listening experience!

It’s amazing how much detail the AMT driver is able to extract, especially in the treble range. Thanks to its speed, the sound reproduction achieves three-dimensional imaging and spatial depth. The benefits are many, including more dimensionality for instruments, greater intimacy for vocals and a more defined sense of space. The speed and precise timing also help to clearly separate overlapping mix elements such as multiple voices or percussion. I did not find this wealth of detail tiring, nor did I notice any unwanted sharpness. In fact, for technical audio tasks such as editing, these specific driver characteristics are remarkable.

In the bass, the HEDDphone TWO GT is tightly defined, with solid tonal accuracy, dynamics and deep extension. Remember that its sibling was deliberately more reserved in this area to match the brand’s monitor speakers. Looking at the frequency response, the GT shows a slight boost around 80 Hz and is much more linear below 60 Hz. I don’t get the feeling that it overcompensates here; the sound still has a defined contour and remains somewhat lean. This can be heard in Donald Fagen’s ‘Morph the Cat’ or Whitney Houston’s ‘My Love is Your Love’.

A few other examples: The delightfully nostalgic ‘I Fall to Pieces’ by Pasty Cline shows the typical left/right stereo distribution of older recordings, offering a little historical journey back in time. Similarly, I’ve rarely heard the bass sound so three-dimensional on Hank Williams Jr.’s ‘Family Tradition’. The new Larkin Poe production ‘Bloom Again’ also sounds perfectly coherent. Rebecca and Megan Lovell’s voices are perfectly balanced and very intelligible.

The unit is no slouch when it comes to heavier rock genres either. AC/DC’s ‘Fire Your Guns’, The Haunted’s ‘Warhead’ and Alice in Chains’ ‘Check My Brain’ all feature distorted guitars in a variety of tonal flavours. Meanwhile, tracks such as Meshuggah’s “Bleed” and Slayer’s “Repentless” showcase specific mid-range tunings that are a matter of personal preference.

All in all, the result is totally convincing – bravo!

Conclusion

The HEDD Audio HEDDphone TWO GT from Heinz Electrodynamic Designs is a real rarity on the market. With a recommended retail price of €2,199, it is aimed at discerning music lovers looking for an audiophile solution for home or studio use. Although I wasn’t able to compare it directly with its sibling, the HEDDphone TWO, the same sense of luxurious listening was evident.

I can definitely confirm that this review unit delivers what the GT suffix suggests – essentially a high performance engine enhanced with added comfort. This is a top-of-the-range headphone that, thanks to its unique Air Motion Transformer, occupies a niche between conventional dynamic solutions, electrostatic and planar magnetic designs. A personal listening session is highly recommended.