HEDD HEDDphone - User review - Gearspace.com
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5 5 out of 5, based on 1 Review

...the advanced AMT folded-diaphragm with VVT tech offers a unparalleled listening experience.

13th May 2021

HEDD HEDDphone by Arthur Stone


Introducing the HEDDphone: the first full-range Air Motion Transformer (AMT) headphones – ever. Very high-quality, comfortable and accurate headphones. Priced accordingly.

The headphone diaphragm uses very similar technology to the AMT tweeter in HEDD's Type- and Tower monitors but with technological advances – Variable Velocity Transform (VVT) – which enables the folded diaphragm to output a full range of frequencies from 10 Hz to 40 kHz.

The AMT is able to output air significantly faster than other designs. Incredible punch from drum kit recordings; the texture of the skin surface and the snare wires clear as day. The centre image is strong with clear gradations to the full width of the soundstage. Deep well-defined bass, spacious mids, and treble with smooth air. A satisfying, involving soundstage. In addition to providing an entertaining listening experience the HEDDphones detail make them eminently suitable as a tool for audio work.

Whilst the 718g weight is more than usual for modern headphones, the symmetrical, balanced design and mechanical distribution negates feelings of heaviness; unless the head is tilted forward the HEDDphones feel like 350g. The HEDDphones are very comfortable, even for extended use.

HEDD Audio (Heinz Electro Dynamic Design) is based in Berlin, Germany. and founded by Klaus Heinz and son Frederik Knop, who recently took part in a Gearspace Q&A and we also reviewed the new Mk2 Type-20 3-way monitors which scored 5 stars.

Price: 1,427.23 Euros; US $1,889; UK £1,479

3 years warranty on product registration.

Includes either HPC1 (6.3mm jack) or HPC2 (XLRm) cable; the jack is for unbalanced systems and the XLR balanced. Both cables 2.2m length and terminating with 2 mini-XLRf to connect to the HEDDphone.

The cable is high-quality braided and doesn't transfer mechanical noise (e.g. cable rubbing on desk or shirt collar) from the cable to the headphone shell. A big plus IMO. The inner cable is pure oxygen-free copper with high-conductivity/low impedance, and REAN connectors and customized HEDD Y-split. In addition the HPC1 has separate signal paths for low crosstalk; and the HPC2 has a fully-symmetrical design for zero crosstalk. Both versions have high shielding to eliminate noise.

The cables are also compatible with other headphones.

The presentation box is a high-quality card with magnetic catches and foam inserts; this is great for delivery, as an initial display case, or for light storage protection. Perhaps HEDD could add some value here by creating a similar case that will transform, origami-style, into a headphone holder for the desk. The case is such high-quality that it would be great to see its utility extended.

Tech Specs:
Concept: Open over-ear headphone with Air Motion Transformer and VVT Technology
Frequency response: 10Hz – 40kHz
Efficiency: 87dB SPL for 1mW
Impedance: 42 Ohms
Connector: Mini-XLR
Weight: 718g
Warranty: 2 years from original date of purchase
Replaceable ear pads.
The HEDDphone's impedance of 42 Ohms requires a generous amount of gain from the headphone amp. In comparison, the Audeze LCD-1 Planar headphones are rated at 16 Ohms (used with 25% interface headphone amp gain); AKG K702 is 62 Ohms (at approx. 50% gain); typical earbuds 32 Ohm; Meze Empyrean 31.6 Ohms; Austrian Audio Hi-X55 25 Ohms; ADAM SP-5 70 Ohms.

In practice, different designs (cone speaker vs planar vs AMT) have different power/gain requirements relative to impedance. The HEDDphone was happy taking 75% + on a standard interface headphone amp dial and IMO they will benefit from a dedicated monitor controller or amp – that said everything worked perfectly well: there was always enough gain on every headphone outlet I tried and never a sense of the image being overpowered and blown-out nor starved of energy.

Some other high-end manufacturers include a 3.5mm small jack option (with the specific aim of connecting their headphones to domestic devices e.g. phones/tablets) whereas HEDD offer the larger 6.3mm jack (unbalanced) and the (balanced) XLR cables and that indicates the intended role (audio and audiophile) but personally I'd try a small jack if that suited my needs.

Back to the Future: The form and function of the HEDDphone give it a modern design aesthetic; not dated in a retro, steampunk sense; more the cutting edge of futurism. Jokes about cybermen aside, most effective headphones have a distinctive look - big technological ear muffs – and even if the look is quirky all that fundamentally matters to the wearer is sound and comfort.

The comfort-level is top-grade: the stitching on the soft leather and transition in texture to the smooth metals is worthy of a supercar; like comfy slippers for the ears.

The combination of solidity of the physical weight, quality feel, and urban-industrial chic, gives the HEDDphone a classic and timeless presence.

The video shows the HEDDphone being hand-manufactured at HEDD Audio's production facility in Berlin.

The Weight: OK, lets discuss the elephant in the room...all 718 grammes of it. Most headphones weigh a lot less, maybe 400g. The weight is due to the larger magnets required for the AMT design. The thing is that on the head the HEDDphone feels like 350g. Somehow HEDD have managed to design a mechanism that makes the weight evenly-distributed. Even leaning forward or backward the HEDDphone stayed firmly in position and 'light as a feather.' Remarkable.

The Kapton Factor: The membrane is light as a feather – lighter. Kapton is a polyimide 'plastic' film that is strong, stable and consistent across a range of temperatures and operating conditions; it is used widely for flexible electronic connectors, printed circuits, and in spacecraft and satellite components.

The hand-manufacturing of the Kapton membrane and diaphragm is undertaken by ex-watchmakers shown in this video.

More information about the AMT design is discussed in the HEDD Type-20 Mk1 monitor review.

The Air Motion Transformer and VVT technology: A simple hand clap is enough to demonstrate how compressing air (between the hands) creates a pressure wave and an explosive sound. By varying speed, power, hand shape, a variety of clap sounds can be achieved.

There's a similar principle at play in the Air Motion Transformer (AMT): the folded membrane expels air as a pressure front when the folds are compressed (in this case by an electrical impulse in a magnetic field).

To move from producing a handclap to the reproduction of an instrument or entire orchestra required two significant inventions: the AMT and Variable Velocity Transform technology (VVT). Klaus Heinz founder of HEDD is the creator of these technologies which are adapted and improved from Oskar Heil's original design.

Initially the AMT was used exclusively with tweeters but with VVT the AMT's range is expanded to reproduce frequencies from an incredible 10 Hz to 40 kHz.

In laymans terms, with VVT some sections of the membrane are folded differently to other sections and this variation of thickness is what enables the membrane to cover a broader range of frequency reproduction than the evenly-folded AMT.

The HEDDphones embody this lineage from Oskar Heils design through Klaus's improvement and implementation in professional equipment and then an improvement of capability with the VVT design-power.

In this video Klaus discusses the development to make the AMT smaller and more compatible with dome tweeters – originally with hi-fi companies. In the general discussion about HEDD Audio design and engineering, Klaus stresses a physics-led approach to create the optimum technical conditions for sound to be reproduced accurately and realistically.

Regular dome tweeter push air from their surface whilst the AMT squeezes the air out from its folds: this larger surface area within the AMT's folds creates a four-to-one compression ratio meaning that the air moves 4x faster than the membrane can; this fast transient response leads to a clear and vivid sound...and this character is perfectly suited to headphones.

Oskar Heil had originally tried an AMT headphone design but was unsuccessful. HEDD's first prototypes lacked balance with dipped mid frequencies. Klaus and HEDD then developed the 'variable velocity transform' (VVT) which took a basic AMT and folded the diaphragm with variable geometry to create an even frequency response for headphones. The next step was to improve efficiency of the design and Klaus stresses the importance of a good headphone amp to get the best from the HEDDphone: 1 watt minimum and 2 to 5 watt for louder use.

By the nature of their design AMT's require a different magnetic array than a regular voice coil or planar diaphragm. HEDD needed to use larger magnets to cross the gaps in the folds and the downside is the added weight.

In the video Klaus and Frederik stress the 3Dness and revealing quality of HEDDphone: acoustic music, music with large fast dynamics, reverb tails, ambience, all sound more detailed. As a listener I really felt connected to the room or studio space in which the original recordings were made.

Listening tests: The HEDDphones segue well with the tone and dynamics of the HEDD monitors and sharing many of the positive attributes: detail in soundstage and resolution between instruments; not hyped; non-fatiguing; immersive listening experience; great range and even dynamics. Many of the headphones I review or listen through have an outstanding characteristic - whether positive or negative – whereas the HEDDphone is all positive with no negatives. Really.

Usually I might need to adjust my perception to the headphone whereas the HEDDphone sounded 'right' from the go, and particularly when transitioning from the main HEDD monitors.

The solidity, dense weight, and head-hugging design assisted in perceiving the lowest points of frequency where sound becomes feeling – a sense of physical connection. Again, the similarity to the main monitors with BASS08 subwoofer was very close in the positioning of low frequencies in the soundstage.

One thing I did need to adjust for was the size of the soundstage: larger than planar headphones I've used but not quite a big as some quality headphones with conventional drivers. In addition the main monitors have a glorious, large soundstage so the HEDDphones do sound more constricted on immediate comparison but over a few minutes my perception changed and everything felt natural and well-proportioned. The bass 'depth' of the main monitors with sub was well-reproduced in the HEDDphone.

Under the Boardwalk: At the end of the day, what are the downsides? The HEDDphone is expensive professional gear that is not designed for non-studio/domestic or outdoor environments. The danger is that small particles of dust or debris (especially metallic) will become trapped in the magnetized membrane folds leading to damage and/or inefficiency. Sand blown at the beach, city grime, or toast crumbs, will ruin your day. The HEDDphone is a precision instrument and deserves to be treated accordingly.

Conclusion: Headphones don't come much better than this, if at all – in fact, the HEDDphone is unique: the advanced AMT folded-diaphragm with VVT tech offers a unparalleled listening experience and clear insight into mixes. In addition to segueing with HEDD monitors (and other high-end rigs) the sonic reference is a reliable benchmark for professional music production and translation of mixes to consumer playback systems.

The bespoke design enables sonic precision without ear fatigue and despite the physical weight the HEDDphone is comfortable for long sessions. The hardware is top-quality: designed and hand-manufactured in Berlin by experts.

Like the HEDD main monitors the HEDDphones are well-priced given their performance and position amongst other notable products in this class.

Gearspace Points.

Sound quality: 5/5 Linear, detailed, non-fatiguing sound. Strong soundstage without hyped width. Natural and relaxed.
Features: 5/5 Unique VVT technology. High-quality design, engineering and components.
Ease of use: 5/5 Sonic capabilities are well-suited for audio work and leisure-listening. Great fit and comfortable for long sessions. Care should be taken with this precision instrument.
Bang-for-buck: 5/5 Even from the home/project studio perspective the HEDDphone makes sense in terms of price/performance. The 1000 (of your currency) is the threshold to headphones that are sonically-reliable and capable of pro performance in terms of dynamics and detail. The HEDDphone is a hand-manufactured, luxury product.

Attached Thumbnails
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Last edited by Arthur Stone; 15th May 2021 at 02:05 AM..

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