THE CENTERPIECE OF OUR PRODUCTS: THE SOUND TRANSDUCER
The pursuit of innovation and the continuous development of technologies have characterised our products for more than 100 years now. This was the case back when Eugen Beyer founded the company, and it is still the case today. There’s nothing that can’t be improved. Getting the best audio quality out of our products is our highest priority. And we work on this every day.
The centerpiece of our products and therefore the part primarily responsible for their audio quality is the sound transducer, also known as the driver. So, today we’re getting a little more technical as we delve deeper into the world of our sound transducers and show you how our technologies have defined the audio quality of beyerdynamic products for decades.
TABLE OF CONTENTS
What does a sound transducer do?
Electrical voltage, sound waves and sound generation – to many, these terms sound like they belong in a physics lesson. For music lovers, however, they have a completely different meaning. For example, if you want to understand how you can enjoy music through headphones, sooner or later you will come across the term sound transducer. This component is crucial for audio transmission in headphones, loudspeakers and microphones.
How do sound transducer work?
Allow us to briefly explain the physics behind every listening experience. In headphones, the sound transducer converts electrical signals (electrical voltage) into mechanical movement, which is then converted into acoustic signals (sound waves). This also works the other way round: In a microphone, for example, acoustic signals are converted into electrical signals. The most important component here is the membrane. Alternating current causes this to vibrate and a transducer converts the audio signals into electrical impulses.
Types of transducers
Over the years, technology has constantly evolved. There are now various types of transducers that have different areas of application, and that differ in terms of their design.
In total, there are electrodynamic, magneto or electrostatic, and balanced armature transducers. The electrodynamic principle is the most widely used and offers high playback quality. Our high-end headphones feature a special sound transducer based on the electrodynamic principle – the Tesla sound transducer developed and manufactured by us in Germany. Allow us to explain what this is all about.
The magic number for sound transducers: 1 Tesla
1 Tesla is the magic number for sound transducers. The unit “Tesla” is used to measure the strength of a magnetic field acting on a current-carrying conductor. 1 Tesla is the threshold in the magnetic field of sound generation and values above 1 Tesla are considered difficult to achieve in headphone construction. However, achieving a value above 1 Tesla has immense advantages. The voice coils can then be more delicate and therefore react more quickly. As a result, the sound produced becomes more precise and richly detailed. At the same time, this increases the energy utilisation, meaning the listener can play louder with less energy input.
The unit of measurement was named after the electrical engineer Nikola Tesla in 1960. Driven by the desire to solve seemingly unsolvable problems, Tesla began experimenting with wireless energy transmission at a very early stage. And to this day, he continues to inspire the inventive spirit of our developers to revolutionise audio technologies. Tesla was also the inspiration for the Tesla sound transducer with Tesla technology, which works according to the electrodynamic principle.
DT sound transducer
Important sound transducers at beyerdynamic that deserve special mention are our DT sound transducers, which are used in our PRO classics such as the DT 770 PRO, DT 880 PRO and the DT 990 PRO, as well as in our Edition headphones. The dynamic plastic sound transducers have a magnetic flux density of 0.6 Tesla.
With our DT sound transducers, a basic distinction is made between two- and three-part coil systems. Our (80-ohm) DT 990 PRO, for example, has a two-part system and reacts somewhat more slowly, which is why a slight treble attenuation can also be detected here. The 250-ohm version of this model, on the other hand, has a three-part coil system, which ensures slightly faster performance. As a result, the high frequencies can be reproduced more faithfully with this model, while the treble sounds more present. You can find more details on the structure of the driver and its effect on the sound here.
The delicate coil of a 600-ohm system reduces the moving mass even more significantly compared to the other variants and thus enables even better impulse fidelity.
Products with DT sound transducers:
On the way to 1 Tesla: Tesla technology
Every technology has its physical limits. The automotive industry is struggling with the range of electric vehicles, while solar cell manufacturers are seeking greater efficiency in power generation. The aim is to get as close as possible to the magic limit of 1 Tesla. Named after the pioneer of the alternating current, Nikola Tesla, our specially developed Tesla driver has been the reference for master-class sound for more than 15 years.
Making the sound experience better and better is something we have always aimed to do and drives our development work. In the 2000s, a market for high-end headphones opened up, to which we responded in 2009 with the first generation of our audiophile high-end T1 headphones. In order to create high-end sound with this headphone model, we worked particularly hard to reach the magic 1 Tesla limit.
Tesla sound transducers
Our passion and spirit of development paid off. The Tesla all-metal system we developed consists of a neodymium ring magnet with an optimised magnetic field curve. This ensures that a magnetic field with a magnetic flux density of approx. 1.2 Tesla is created inside the sound transducer.
This electrodynamic sound transducer is used in our high-end headphones, for example in the T1 and T5. From the third generation of the T1 and T5 high-end headphones onwards, the sound transducers have been arranged at an angle to create the most spatial sound possible. This gives the listener the impression that the music is coming from the “front” of the stage and is equivalent to a concert experience. This means your music of choice keeps its musical details and nuances during playback and sounds as close as possible to the original recording. This transparent, spatial and distortion-free sound is what characterises our Tesla driver.
The special feature of our Tesla driver
Only a few components need to be used in the Tesla sound transducer, resulting in low tolerances. The strong magnetic field is concentrated in the air gap inside the headphones, which means that the external scattered magnetic field is extremely low and losses are minimised. In order to create precisely defined flow conditions for the moving air masses in the sound transducer, a precision fabric is used instead of a standard fleece. This optimises the frequency and phase response. A full metal housing shields the voice coil of the Tesla sound transducer from electromagnetic fields. In combination, the individual components achieve a value of 1.2 Tesla. In other words, a value that is slightly above the magic limit of 1 Tesla.
With the Tesla driver, we managed to exceed the magical limit of 1 Tesla for the first time in 2009 and create high-end sound in a class of its own. In the years that followed, we continued to develop our Tesla driver and worked on bringing high-end sound to smaller headphone models.
Miniaturised Tesla transducer
We have achieved this by developing our miniaturised Tesla driver, which is only 11 millimetres in size compared to the 45 millimetre driver used in our high-end models. The miniaturised Tesla sound transducer was specially developed to enable full hi-fi enjoyment even in its compact design.
The 11-millimetre dynamic one-way driver impressively demonstrates the merging of beyerdynamic’s acoustic expertise, engineering and craftsmanship.
The public was able to see this innovative strength for themselves in May 2017 when we presented our XELENTO in-ears at the High End trade fair in Munich: our first wireless in-ear headphones for audiophiles with Bluetooth®, APTX™ HD and Tesla technology.
A unique audiophile sound experience thanks to outstanding development work
Ring magnets – 16 times smaller than in the reference T1 headphone – and ultra-fine voice coils delivered an impulse fidelity that was second to none among in-ear models. The extended frequency response made every sound detail audible, while a powerful, precise bass rounded off the sound profile without pushing itself into the limelight. The first generation of the XELENTO wireless showed what was technically feasible in its class up to that point – the highest level of innovation and development made in Heilbronn.
Making the sound experience better and better
For the second generation of XELENTO in-ears, which we presented in 2020, our development team took on the challenge of improving the sound transducer once again and perfecting the sound of the in-ears. An even more delicate sound and more lightness was to give the second generation XELENTO an upgrade to its sound and make the listener’s sound profile even better.
Products with Tesla technology:
STELLAR.45 driver
Our engineers and acousticians also wanted to bring what they had created with the Tesla system for our high-end headphones to the studio segment. They therefore worked on a new driver that combined the origins of our classic DT driver with the innovative Tesla technology. The result was a sound transducer that converts electrical signals into sound signals as efficiently as our Tesla sound transducers and just scrapes the Tesla limit.
When developing the STELLAR.45 driver, our engineers focused on making the transducer highly efficient as well as capable of delivering a superb sound performance. By efficiency, we mean the ability to convert electrical signals into sound with as little loss as possible. A high level of efficiency means that the speakers in the headphones are able to perform well with mobile devices as well as on stationary systems such as digital audio workstation or headphone amplifiers. With the STELLAR.45 driver, you don’t have to worry about the impedance of your headphones – the driver always guarantees good performance. Thanks to various technical techniques, we were able to develop a driver that is superior to the DT drivers in our PRO classics in terms of efficiency.
On top of this, we also put a lot of work into enhancing the design of the transducer’s voice coil. A technical highlight is that a CCA wire was used for the coil, which enables a low power resistance and a low mass for pulse fidelity. Thanks to this wire, we were able to produce a comparatively long, yet very light voice coil. In combination with an innovative diaphragm structure, we were able to create a speaker that reproduces the acoustic signal with a minimum of distortion even at higher volumes. This special structure also prevents the uncontrolled compression and buckling of the membrane at high deflections. The resulting resonance-free high-frequency reproduction is equally suitable for open and closed headphones.
We have also automated the complex manufacturing process for the STELLAR.45 driver in Heilbronn. This enables us to achieve exceptionally high quality and consistency. More detailed information about our STELLAR.45 transducer can be found in our blog article”The new beyerdynamic driver in our PRO X headphones“.
Products with STELLAR.45 driver:
We have been striving for unadulterated sound for 100 years now. Our transducers are the centerpiece of our products. Thanks to our high level of “Made in Germany” development and engineering skills, we are able to create high-quality audio products that inspire our customers all over the world. And we work on this every day. So, look forward to seeing how our technologies develop and what milestones we will achieve in the future.