September 2021

HEDD HEDDphone Headphone Review
Meet the New Boss?
Definitely Not the Same as the Old Boss
How does the HEDD HEDDphone measure up to the competition? Our comprehensive review of these very unique headphones. The Empyrean have a new challenger.
Review By Trav Wilson

  Can a pair of headphones be priced at almost $2,000 and still be considered a bargain or even a good buy? I've been wondering about that a lot of late. It depends on your perspective, I suppose. And your pocketbook. The HEDD HEDDphone might make you reach for your wallet.

What if those headphones compare favourably with the absolute top-tier performers; including some that are priced significantly higher and some more than twice as much. What if they are a real contender in materials, craftsmanship, and (most importantly) sound reproduction? Make no mistake about it – the Heinz Electrodynamic Designs HEDDPhone belong in the top tier of headphones available.

Several of the best headphones come from long-established German headphone companies; including Sennheiser, Beyerdynamic, and Ultrasone.

So what happens when an upstart company from their homeland comes along, and with their first-ever headphone, are flexing enough muscle to disrupt the status quo?

Enter Heinz Electrodynamic Designs (HEDD) and their (cleverly named) HEDDphone. 

HEDD "builds handcrafted professional studio monitors and headphones in Berlin since 2016. HEDD's advantage is the in-house developed signature Air Motion Transformer driver." The idea of the AMT, which features a folded elastic diaphragm, was initially conceived in the early 1960s by German-American physicist Oskar Heil. HEDD featured this design as tweeters in their speaker line-up for years before adapting it for headphones.

The AMT driver is visible through the outer grill.

In 2020, HEDD further evolved the AMT into full-range (10Hz to 40kHz) drivers used in the HEDDphone. HEDD is the first (and only) company to use a full-range AMT driver in headphones. They created something entirely new for this established industry.

Ok, they sound pretty cool, don't they? But sometimes, it doesn't pay to be an early adopter. Often, it's better to wait for a technology to mature, to work out the kinks, to refine, and to improve. Should you dive in and embrace something genuinely revolutionary and new? Or are one of the traditional companies and driver types a better (and safer) buy?

Understandably, there's been a lot of hype and interest in this unique pair of headphones over the last couple of years. Let's jump in and see what the HEDDphone have to offer in 2021.

The HEDD logo is prominently displayed on the sides of the HEDDphone.

Company Overview
Physicist Klaus Heinz and his son, Mastering Engineer and Musicologist, Dr. Frederik Knop founded HEDD Audio in October 2015. Klaus Heinz serves as HEDD's CTO, while Dr. Frederik Knop serves as CEO, in charge of the brand and sales.

Located in Berlin, HEDD produces loudspeakers and headphones and focuses on incorporating and refining Heinz's decades-old Air Motion Transformer (AMT) design. HEDD's products target audiophiles and professional music production industry.

"In 2019 Heinz has started developing a full range Air Motion Transformer to break new grounds for this superior transducer principle. In order to reproduce the complete audible frequency band (and beyond), the HEDDphone incorporates VVT technology (Variable Velocity Transform). It introduces a new, variable diaphragm geometry that expands the AMT principle to a linear full range (10Hz to 40kHz) headphone transducer."  -- HEDD

Technical Specifications 
· Form: Open-back, over-ear headphones
· Drivers: Air Motion Transformer (AMT)
· Impedance (Ohm): 42 Ohms
· Sensitivity (dB): 87 dB SPL for 1 mW
· Frequency Response (Hz): 10Hz to 40kHz
· Removable Cable: Y
· Source Jack: 6.35 mm
· Cup/Shell Jack: Mini-XLR
· Weight (g): 718 grams
· Warranty: Two to three years

HEDD guarantees that their products are free of defects in material and workmanship for two years from the original purchase date. This warranty can be extended to three years if the product is registered within the first six months after purchase. It's excellent to see a company stand behind its products like this.

Packaging
Everything about the HEDDphone is big. And this super-sized experience starts with the box. Seriously, how can a box impress? Simply make it enormous (290mm x 365mm x 155mm). Removing the outer black paper slip-off sleeve reveals a cardboard box with a fold-up top and magnetic closure.

Inside the box, the HEDDphone are nestled in laser-cut back foam and covered by a full-size specification sheet, with a separate cardboard box containing the cable. The pair that I've spent the last month with are review loaners, so the box shows use from an undisclosed number of previous listeners.

Now that's a box!

Due to the paper construction, the bottom edge hinge on my box is tearing, and the glued-on foam piece to fit in the headphones' center was unattached when they arrived. While the packaging impresses at first glance, it's pretty clear it won't hold up well as a permanent storage box for years of listening.

By comparison, the Ultrasone Edition 15 Veritas (which arrived this week and are admittedly far more expensive) come in a stunning full-leather storage case befitting their TOTL status.

While a case doesn't impact how headphones sound, after a certain price point, extras and a bit of pampering are to be expected. Unfortunately, the HEDDphone packaging seems like a bit of a cost savings attempt. Perfect for shipping safely, but not for display or long-term storage.

In the Box
· HEDDphone
· Cable (220 mm, 6.35 mm, dual mini-XLR)
· User Guide

And that's it.

Is it enough? Sure, a cable and the headphones are technically all that is needed. But again, this list of accessories seems more minimal than is necessary. Since the HEDDphone are notably inefficient and will likely be paired with higher-end amplifiers that feature a balanced output connection, the inclusion of a second balanced cable, or a single cable with a balanced to single-ended adapter, would just make sense.

The cup jacks are standard four pin mini-XLR.

HEDD does offer a balanced cable, the HPC2, for $160. Like the original, it features Oxygen-Free Copper (OFC) and industry-standard REAN connectors.

Cable
The cable is a twisted dual-wire design, wrapped in a smooth black fabric sheath. Oddly, none of the plugs are gold plated. It's a nice feeling cable but is less supple than I prefer. If bent by hand, it will hold the bend.

The HEDDphone cable.

Reportedly, the mini-XLR plugs and jacks are uniquely wired. Where Audeze uses pin 1 for negative, the HEDDphone use a pin 1 positive configuration.

A red ring on the connector subtly indicates the right side, and it is necessary to double-check the proper side with the small L/R indicator printed on the inside of the band.

Ear Pads
Of note, the seams on the large, plush, leather ear pads face front. I found this to be an anomalous oversight, as the overall design of the HEDDphone is so refined. Perhaps it was intentional, but I'd assume most folks would want the seam to be on the bottom or backside and less visible when wearing. The inside surface of the ear pads is perforated.

Check out how cushy that pad is!

Which brings us to another point, how do you look with the HEDDphone on your head? No word of a lie, shortly after they arrived, my wife and I took turns putting on the HEDDphone, while the other one collapsed in gales of laughter. I believe 'Princess Leia Ear Buns' may have been used to describe the HEDDphone on-ear appearance.

Seriously though, each ear cup plus ear pad is about 70mm thick. Even compressed on your head, this adds almost 130mm of width. Since the average human noggin is around 165mm wide, donning the HEDDphone just about visually doubles the width of your head. The curved headband flexes almost straight across to contain this monstrosity.

They look silly to wear. Or extremely purposeful and clearly high-end. Just a matter of perspective, I guess.

Design
Big. Really, really big.

And heavy. At 718 grams (1.6 lbs) the HEDDphone are the most massive headphones I have ever encountered.

The HEDDphone are the fine German luxury car of the headphone world. The 7 Series BMW. The Mercedes-Benz S-Class with silver highlights. They are gorgeously designed and luxuriously appointed. Lavish and ultra-comfortable black leather band and ear pads. Sculpted aluminum yokes and sliders. Super-classy and obviously expensive.

Which is really the point when you read between the lines. The Heinz Electrodynamic Designs HEDDphone are designed for customers looking for the best possible music experience with a pair of headphones and designed to compete with reference quality products like the Meze Audio Empyrean.

The shape, size, and weight of the HEDDphone are a clear result of the AMT driver technology. They simply can't be smaller and lighter and contain those two colossal drivers. The question is if the trade-off is worth it because, after an extended listening session, they feel a bit like you've been balancing one of those substantial luxury cars on your head.

The headband is nicely padded and features a perforated bottom surface.

Perhaps I'm simply a pencil-necked weakling, but I enjoyed my listening sessions far better when I could support my head (and the HEDDphone) with a high-backed chair and pillow.

HEDD has done all they can to offset the weight. The ear pads are the thickest and softest I've ever felt. The headband is well-padded (although it might benefit from a bit more width) and features a perforated fabric underside to improve top of head breathability. The clamping force is relatively high, but this does serve to offset some of the downward pressure.

The generously cushy ear pads and head band do what they can to offset the weight.

The Heinz Electrodynamic Designs HEDDphone are a gorgeous example industrial design. The silver vented grill and golden driver material can be glimpsed through the outer black metal mesh. They are clean and purposeful looking and feel somehow quintessentially German in design. I believe the HEDDphone meet fellow countryman Dieter Rams' ten principles of 'good design.'

Crinkly Noise
One unusual quirk of the AMT driver is that when positioning the HEDDphone on your head, you will hear a very noticeable crinkly sort of sound. Think of what crumpling thin wax paper sounds like. Now imagine that every time you adjust the HEDDphone. The changing air pressure causes the drivers to flex and make that sound.

The accordion folds of the AMT driver are open under the ear pads.

Off-putting and initially concerning, to say the least. Thankfully, it's entirely normal and doesn't affect the sound quality in any way. The AMT driver is a very thin, accordion-folded structure, and the air pressure caused by external movement causes it to flex and make that noise.

During use, I never encountered the crinkly noise. It only occurs when repositioning the HEDDphone.

Air Motion Transformer (AMT)
What sets the HEDD HEDDphone apart from every other headphone is their proprietary full-range driver design. Oskar Heil originally proposed the idea of the Air Motion Transformer in the 1960s. Rather than traditional piston-like diaphragms that move air in an equal ratio to the diaphragm motion (that is, the air velocity matches the diaphragm velocity), the AMT design accelerates the air four times faster than the diaphragm.

A closeup view of the AMT driver.

Improved airspeed should yield sonic improvements in transient response and dynamics.

The AMT uses a folded elastic diaphragm design. Each fold opens and closes in an alternating pattern, accordion-like, to inhale and exhale the air and create sound. This bellows design is very unusual in the headphone and speaker world. In the 1990s, Heinz further refined the AMT into a high-fidelity tweeter for loudspeakers.

The basic design of the AMT driver. (From: hedd.audio)

"The Air Motion Transformer is an electromagnetic driver, as it is based on the Lorentz force that moves the air in the single folds. The diaphragm itself has an aluminium circuit printed on it (violet arrows) and is surrounded by a strong magnetic field. The graphics in and around the small circles show the motion of the individual foils producing a sinusoidal waveform: from where it starts (black circle) through the positive (green circle) and negative (red circle) half-waves." -- HEDD

The resulting air flow (blue arrows) is four times faster than speed in which the individual folds move, which is a big advantage when it comes to reproducing music signals with fast transients (cymbals, plugged guitar strings, etc.)." -- HEDD

The technology inside the AMT driver. (From: hedd.audio)

VVT Technology
The key to adapting the AMT driver for headphone usage was to adapt it to reproduce the full range of frequencies. This meant creating an entirely new diaphragm geometry. Heinz changed the AMT's traditionally fixed geometric structure to incorporate a unique fold structure, varying in width and depth.

HEDD calls this Variable Velocity Transform (VVT) Technology. The result is an AMT driver capable of linear reproduction from 10 Hz to 40 kHz. Impressive indeed.

A consequence of this new fold structure is a decrease in efficiency. The larger folds required for bass reproduction necessitate a stronger magnetic field. A low-efficiency driver needs a high current amplifier to work correctly, and sound as intended.

Amplification
The Heinz Electrodynamic Designs HEDDphoneare a challenging load with a 42 Ohm impedance and 87 dB SPL @ 1 mW sensitivity rating. The infamous HiFiMan HE6, often touted as the least efficient headphones, are rated at 83.5 dB. The HEDDphone aren't quite down to that level, but they are getting pretty close.

This means low-powered portable sources need not apply. This isn't much of a limitation as I can't imagine anyone choosing the HEDDphone for portable usage. The HEDDphone demand a high-current amplifier, and in every way, are more suited to desktop amplifier pairing. High-voltage, low-current OTL tube amplifiers such as the Darkvoice 336 or Bottlehead Crack are not a good fit, and dynamics are significantly impacted.

The SMSL SP200 THX AAA 888 amplifier is a great budget choice for powering the HEDDphone.

The Chord Mojo and xDuoo XD05 Plus can drive the HEDDphone to acceptable volume levels, as these are fairly powerful portable devices but are still not ideal pairings.

The lack of an included balanced headphone cable is fairly glaring when considering their power requirements. The more power you can feed these monsters, the better.

The Heinz Electrodynamic Designs HEDDphone simply sound better when driven with vast, effortless power to back them up. Bass punch and depth improve. Clarity and focus increase.

Sound
The HEDDphone are big and heavy. They are luxuriously designed and impeccably constructed. They contain a unique and innovative driver design. They need a powerful amplifier to work properly.

But all of that is secondary to the real question. How do they sound?

Utterly divine. Rapturous.

All that physical mass is offset by a light and weightless sounding pair of headphones. Their large size translates into a vast airy soundstage. More than simply a pair of headphones, you've donned an entire listening room when you place the HEDDphone upon your head. A huge and lovely space where music is delicately and beautifully portrayed.

"The HEDDphone brings the enormous dynamic capabilities and the superior sonic resolution of the AMT principle to the world of top-end headphones. HEDDphone excels where it really matters: in accurate, untamed, and touching music reproduction." -- HEDD

Those unique AMT drivers yield a distinctive sound. They don't sound like any other dynamic or planar magnetic driver headphones that I've experienced. Their high-frequency design heritage shines through with a terrific feeling of clarity and transparency.

Thankfully the HEDDphone don't take this too far, and they are not simply detail scalpels. There is plenty of fun to be had in the listening experience.

The frequency response graph measured on a miniDSP EARS testing fixture. Both channels averaged.

The HEDDphone are relatively neutral overall, with fantastic extension on either end of the frequency spectrum. The sound is balanced, with the delicate, airy highs firmly anchored by solid and subterranean bass. Neither end seems boosted, and the midrange sits a little behind these subtly emphasized extremes.

Further adding to the 'light' feeling of the HEDDphone is their impressive transient speed. Resolution abounds, and the music is delivered with detail and accuracy. Yet, it's the feeling of open space that envelops the listener that I find most impressive. Space is conveyed naturally, feeling neither forced nor artificial.

Bass
The HEDDphone low frequencies are both impressively tight and deep. This may come as a surprise, as the AMT drivers are essentially redesigned tweeters. But let me assure you, Heinz worked some serious technical magic and transformed the AMT into a wonderful full-range driver. The only compromise here is that it requires sufficient and proper (current rather than voltage) amplifier power to deliver the low-end properly. 

Balance and control reign supreme. It's not an artificial or boosted bass experience. The HEDDphone provide a different and more subtle experience than planar magnetic bass response. Unique, but undeniably very, very good.

The outstanding sense of space begins in the bass regions. I typically think of space being conveyed through the higher frequencies, but with the HEDDphone there is a certain delicacy and refinement present in their low-frequency reproduction.

It's a big and powerful sound when called for, but the bass remains precise and not the incoherent and closed-in presence portrayed by less accurate headphones.

Measuring the frequency response of the HEDDphones.

Midrange
The HEDDphone present vocals with a natural and authentic sounding neutrality. There is no undue, residual low-end warm coloration. However, they do avoid sounding too lean. They have an analytical sound signature, with plenty of clarity and resolution.

The HEDDphone sound relatively effortless with whatever music you throw at (or through) them. They yield the impression that the music occurs in a broad three-dimensional space, rather than from two separate points. Voices sound real and present in this space, exhibiting a physicality and clarity that few other headphones seem to create.

Treble
So how does (what was essentially) a high-end tweeter design handle the high frequencies?

These enormous headphones create sound that is incongruously and wonderfully delicate in comparison with their substantial physical construction.

Treble response is open, resolving, and articulate. There is plenty of detail present, but never any aggressive edginess. I never found the HEDDphone fatiguing to listen to; for as long as my neck was game, my ears wanted more.

Conclusion
I like the HEDD HEDDphone very, very much. If they were half the weight, they'd tick nearly all my boxes for the perfect headphone for home audio. I love the listening experience. Their sense of space, precision, and delicacy. Indisputably, the HEDDphone are genuinely top-tier sounding headphones.

And they are unique. Those innovative full-range AMT drivers mean that the HEDDphone sound like no others. They deftly combine some of the best traits of the finest dynamic drivers, electrostatics, and planar magnetic headphones.

Big size. Big sound.

However, I want to be able to effortlessly listen for hours. HEDD is targeting not only audiophiles but also music industry professionals. While I have absolutely no concerns that they can deliver the necessary precise sound reproduction, I can't imagine wearing the HEDDphone all day, every day. They're just too heavy for that, and unfortunately, that's a bit of a deal-breaker.

YMMV, of course. Perhaps you've got neck muscles to rival the Dwayne 'The Rock' Johnson. Or your listening sessions are limited to an album, or an hour, or two. If so — please don't let me talk you out of auditioning the HEDDphone. Their quality is superlative; their design, materials, build, and sound are truly exceptional.

In this article, I originally mused whether a headphone priced near $2000 could be considered a bargain. It's all about perspective and your own predilections. The HEDD HEDDphone, like every other top-tier pair of headphones, present their own unique set of compromises. Price, performance, size, weight, warranty, materials, and build quality all need to be weighed when making a purchasing decision.

While I'm sad to send the Heinz Electrodynamic Designs HEDDphone on to future reviewers, I'm not quite as heartbroken as I thought I'd be to see them go. These are undeniably gorgeous headphones, but they aren't quite the perfect ones for me. Their compromises aren't my ideal match, but I have nary a doubt that the HEDDphone offer the ultimate "affordable" end-game audio solution for many folks.

Rating
4.5 out of 5 stars

Pros
Incredible sense of space and detail.
Neutral and natural sound.
Excellent extension.
Terrific build quality and gorgeous design.
Innovative AMT driver design yields a unique listening experience.

Cons
Very heavy.
Require robust high-current amplification.
Large size and far from subtle to wear.
The cable is somewhat stiff.
Minimal accessories. No long-term storage case. No balanced cable.

Check Out eCoustics
See many great reviews by eCoustics at this link.

Specifications
Type: Open over-ear headphone with Air Motion
Transformer and VVT Technology
Frequency Response: 10Hz to 40kHz
Efficiency: 87dB SPL for 1mW
Impedance: 42 Ohms
Connector: Mini XLR
Weight: 718 grams
Warranty: Two years from the original date of purchase
Price: $1899

Manufacturer
HEDD Audio GmbH
Salzufer 13/14
10587 Berlin
Germany

E-mail: info@hedd.audio 
Website: Hedd.Audio