By Andy Kong, PR Rep for Kennerton
W. Jennings recently reviewed the Kennerton Rögnir headphones and found much to admire. For those interested in a more technical explanation of the Rögnir’s technology, I’d like to provide a much more detailed explanation and secondary opinion.
“Every once in a while a new product comes along that seems to break all the rules.”W. Jennings
W. Jennings started his Rögnir review with this bold statement, and raved that the new Kennerton flagship is a closed back planar that “does its best to convince you that you are listening to an open-back electrostatic headphone”. We certainly are convinced that Rögnir is a wonderful headphone, but Kennerton seldom reveals the technical detail of their planar technologies. Maybe this is the right time to go behind the scene and explore the secret behind Kennerton Rögnir .
A lot of users, W. Jennings included, are surprised by how light the Rögnir is when they take the headphone out from the package for the first time. The headphone looks solid and that’s always the case with Kennerton headphone because they stick with wood, metal and carbon fiber when they craft their headphone. The weight of the headphone varied according to your choice of wood. For the record, the Silky Walnut version weights 394 grams only, and the Bog Oak weights 406 grams, which are very impressive for a flagship full size closed back planar with wooden ear cups. Kennerton has done a marvelous job to maintain a light-weight design without sacrificing the build quality and audio performance.
Rögnir has been on Kennerton’s R&D agenda for several years, they have developed numerous prototypes before they finalized the current design. The driver and the wooden ear-cup are specifically designed and developed for Rögnir to deliver a perfectly-proportioned soundstage, and unprecedented accuracy in capturing the emotion of your favorite tracks.
The Rögnir driver is composed of:
- 80mm corrugated Polyimide diaphragm
- Semicircular magnet array
- Carbon fiber casing
Semicircular Magnet Array
Kennerton has been well-received among planar headphone users since they debut the Odin at IFA-2014. There were a lot of new in-house developed technologies in Odin that made it a winner of its time and one of the least mentioned features is the patented Semicircular Magnet Array. Kennerton is the first company to implement a semi-circular magnet array in planar headphones. This outstanding engineering achievement has been an integral part of Kennerton planar headphones since they ventured into high-end personal audio sector. They have fine turned the radian and finishing of the magnet array.
Kennerton performed a lot of research, prototyping and measurements when they designed the magnet array for their ice-breaking Odin planar headphone. They noticed that the sharp edges of the conventional rectangular magnets are responsible for some of the audible distortion in the planar driver. By adopting a semi-circular magnet array, the magnetic field intensity will be significantly more uniformed than regular rectangular bar magnets.
The design can eliminate as many obstacles as possible and achieved a smooth and efficient passage for transmission of sound wave. On top of reducing distortion, this will enhance the efficiency of the diaphragm, improve the piston motion, and minimizes direct reflections inside the emitter.
In practice, the semi-circular magnet array achieved a low-resonance behavior that will shine at high frequencies. It will dramatically improve the sound quality of the headphone, and will deliver a natural, organic and delicate sound signature.
The Polyimide diaphragm employs the same technologies as Kapton and it offers the following advantages that make it ideal as high quality planar headphone diaphragm:
- Highly stable: extremely resistant to natural phenomena
- Minimal thermal expansion: allows the membrane to remain stably stretched over the maximum temperature range.
- Chemically inert: extremely durable and reliable due to their nonlabile characteristic in their natural form
- Non-hygroscopic: the membrane will keep its original mass under different environment.
- High heat resistance: the contacts can securely connect to the tracks using soldering
Kennerton was looking for a solution that can maintain the characteristics of the headphones during prolonged use, and delivers the highest quality of audio signal transmission for the entire period of usage. After a lengthy search and exploration, they developed this special Polyimide diaphragm with a Russian provider. On top of being extremely durable, the diaphragm exhibits amazing stretchable capability and that works perfectly for planar headphone application.
Does it occur to you that the diaphragm of Rögnir is 2.5 times the thickness of the diaphragms of Thekk and Thror?
Planar headphone manufacturers work very hard to develop a thinner diaphragm, but what is the reason behind this interesting approach? When you install the driver in a close back body, the resistance of the air pressure is slightly higher than installing the same driver in an open back body.
A thicker diaphragm will have more inertia and compensate extra air pressure. In addition, the diaphragm will also exhibit excessive vibration when it moved quickly in an air-tight environment, and a slightly thicker diaphragm will eliminate the unwanted vibration effectively and bring the driver to optimal operation.
This sounds fairly simple in theory, so what’s the catch? The problem is, diaphragm thickness is inversely proportion to sensitivity of the driver; when you increase the thickness of diaphragm, the sensitivity of the driver will decrease, making it inefficient and demanding on amplification.
Kennerton is well aware of the consequence and they have developed a patent-pending technology to recover, to a large extend, the sensitivity disadvantage. Rated at 42 ohms and 100dB sensitivity, the Rögnir is hardly a difficult load when compare to other full size TOTL planars, and is consider portable friendly if you pair it with a capable DAP or portable headphone amplifier.
A coating can provide additional stiffening to the diaphragm and stiffening is generally desirable when you want to control the resonance behaviors of a diaphragm.
Kennerton has impregnated their planar headphone diaphragms with a specialized coating which was originally used for the sound insulation of submarines. They have accumulated loads of experience with this unique formula and have acquired all the necessary skill to enhance diaphragm stiffness without suffering from cracking or peeling even with very vigorous diaphragm movement.
In the case of the Rögnir, the liquid-composition coating improves the quality of reproduction, to correct, as well as to reduce resonances. Kennerton has solved the problem of spontaneous vibrations at the membrane level when other designs try to tackle the problem at mechanical or external reinforcement.
Last but not least, the coating will improve the technicality of the driver. The detail and resolution is enhanced noticeably, and the soundstage appears extremely open with a lot of layers.
The conductive traces on the diaphragm are also an important part of sound reproduction. Kennerton developed a unique 4-pole design with 16 traces per pole for their TOTL headphones, including the Rögnir. This is an innovative approach to achieve a high EMF and increase the sensitivity and control of the diaphragm stroke at the same time.
Another unique design of Kennerton planar headphones is using a corrugated diaphragm instead of flat diaphragm. This increases the total surface area to well over 80cm circular as stated in the diaphragm description. The corrugated surface will also enhance the stiffness of diaphragm, and will minimize deformation and distortion during diaphragm movement and can sustain a higher sound pressure.
Choice of Wood Earcup
We all know Valentin Kazanzhi, Founder and Managing Director of Kennerton Audio, is a dedicated engineer and he knows his stuff when it comes to headphone design.
When you have the opportunity to hang around with him, it doesn’t take long to discover that Valentin is seriously passionate about woodworking and choice of beautiful wooden ear cups become an indispensable element of Kennerton headphones. Quite often, customers are excited to select their preferred wooden cups which is made exclusively from rare (and expensive) wood, most of the choices are available at no extra charge. Depending on the availability, special edition or stabilized wooden cups are available at a premium; the Stabilized Karelian Birch is an example of that.
Kennerton CNC mills a pair of wooden cups from a single block of wood, and they can create unique acoustic pattern to provide an optimized chamber for the planar driver. This is one fo the key feature that makes Rögnir sounds on par with other Kennerton TOTL planar headphones.
Last but not least, while there are a lot of choice in regard to wooden ear cups, the sonic signature of Rögnir, as reflected by users and reviews so far, has been quite consistent.
We know choice of wood will affect the sonic signature of closed back headphones because the wood becomes part of the sound chamber of the planar driver.
This is not an issue for open back design because the wooden cups are used for functional and decorative purpose only. I brought this up to Valentin and he responded with a big smile.
He told me Kennerton has done “something” to minimize the sonic signature inconsistency of different wooden cups, but this is their secret technique so we have to accept this at their word.
Does it Live Up to its Claims?
W. Jennings concluded his review by saying:
“Everything you think you know about planar magnetic headphones, especially closed back models – has been flipped on its head by the Kennerton Rögnir. It sounds so much more engaging than almost all of the headphones that many would consider the best headphones in the world.”
Rögnir promised an extraordinary closed-back experience and apparently Kennerton has delivered the claims with a lot of respect from users and reviewers. It is a combination of advanced technologies used in the headphone driver and specially designed wooden cups.
The diaphragm plays an important part but it is far from the only reason that makes the Rögnir sound natural, musical and impressively technical in a closed back application.
Kennerton is making a video to elaborate the manufacturing process of their premium headphones with special emphasis on Rögnir. If you prefer a visual illustration after reading these two-part Rögnir review, stay tune for the YouTube video, that is assuming you can resist the impulse to add Rögnir to your shopping cart.
by Andy Kong, PR Rep for Kennerton Audio Equipment