SOUND REVOLUTION WITH THE NEW BEYERDYNAMIC DRIVER
– TESLA.45
With the launch of our new flagship studio headphones DT 1770 PRO MKII and DT 1990 PRO MKII, our new TESLA.45 driver was also used in our products for the first time.
This latest generation of our Tesla driver technology has been redesigned from the ground up and features a 45-mm driver system with excellent resolution, extremely low distortion and outstanding impulse response.
In this blog post, our acoustics engineer Ante gives us exciting insights into the further development of our Tesla technology and the creation of our TESLA.45 driver system.
What prompted you to further develop Tesla technology and why?
Ante: In fact, the first brainstorming sessions for the TESLA.45 were all about what makes a perfect driver and what we need to do to achieve this, without having a specific end product in mind. The main topics were how to reduce the distortion values, how to achieve a uniform frequency response and how to improve the production processes and thus the quality. As the concept became more tangible, it was obvious to equip our premium studio headphones with precisely this driver.
“With the TESLA.45, we wanted to combine the well-established Tesla technology with the knowledge we gained with materials and manufacturing processes when developing the STELLAR.45 and develop a driver system that will continue to meet the demanding requirements of professional recording studios and ambitious home studio users alike.”
Ante, acoustics engineer
How did the name TESLA.45 come about?
Ante: Tesla technology has been a component of high-quality beyerdynamic headphones for many years and represents a milestone in beyerdynamic’s innovation history. Named after the pioneer of alternating current, Nikola Tesla, the term tesla is used by experts to refer to the unit of magnetic induction or magnetic flux density in the metre–kilogram–second system (SI) of physical units. The magnetic flux density is important for headphones – it indicates the intensity of the magnetic field (magnetic field strength) in the air gap of the magnetic circuit. Because a magnetic flux density of more than one tesla is achieved in beyerdynamic acoustic transducers, the term tesla technology is used.
The TESLA.45 also has a magnetic flux density in the air gap of over 1T. Furthermore, the new driver has a diameter of 45 mm, which is an important aspect for the performance of the driver.
What characterises this driver? What is special about the TESLA.45 driver?
Ante: When developing the TESLA.45 driver, the focus was on designing a highly efficient driver that impresses with low distortion and a uniform frequency response. These are key attributes of an unadulterated sound performance. The TESLA.45 diaphragm is a completely new development. With the help of FEM simulation methods, we were able to optimise the vibration behaviour of the diaphragm for clean sound reproduction. In addition to sound radiation, the positioning of the voice coil in the air gap is one of the main tasks of the diaphragm. The diaphragm must position the voice coil in the centre of the magnetic field in the direction of deflection. To ensure centred positioning, the reset force must remain constant over the deflection range of the diaphragm.
A completely newly developed magnet system enables faithful reproduction of complex music signals even at high sound pressure levels. We achieved this by increasing the deflection range so that the voice coil moves in a constant magnetic field at all times.
Distortions can be avoided thanks to the centred reset of the voice coil and the constant magnetic field.
In addition, the special structure of the diaphragm prevents uncontrolled compression and buckling at high deflections. As a result, the sound remains distortion-free even at high sound pressure levels.
The new voice coil design is also decisive for the high efficiency. Thanks to a copper-coated aluminium wire, we have succeeded in developing a voice coil with low resistance and low weight. The low resistance enables playback at high levels even on mobile devices.
Discover our DT 1770 PRO MKII and DT 1990 PRO MKII studio headphones, each featuring two TESLA.45 transducers.
Additionally, you can find more headphones in our online shop, which feature a Tesla driver and guarantee you unique professional-level sound quality. Discover now >
Which components form part of the TESLA.45 driver?
Ante: The TESLA.45 driver consists of the diaphragm assembly, the speaker bearing, the magnet unit and baffle. The diaphragm assembly comprises a membrane to which the voice coil is attached via a voice coil carrier. The voice coil is driven by the electrical music signal and causes the diaphragm to vibrate. The vibrations of the diaphragm generate the acoustic signal.
The magnet pack fitted with a neodymium magnet generates the constant magnetic field in the air gap. The electrical signal in the voice coil is converted into a movement via the physical Lorentz force. All components come together in the speaker’s bearing. The new design of the TESLA.45 bearing enables precise joining of all components. The speaker is positioned in the headphones using the baffle. The fabrics of the baffle are an essential component for the acoustic fine-tuning of the headphones.
How do the STELLAR.45 drivers differ from the new TESLA.45 driver?
Ante: At beyerdynamic, we differentiate between two-part and three-part coil systems. A two-part coil system such as the STELLAR.45 consists of a diaphragm and voice coil that are glued together. This is still referred to as an overhung voice coil. The TESLA.45 has a three-part coil system. In this setup, the voice coil is fixed to a voice coil carrier. As the voice coil underhangs the magnetic field in this design, we speak of an underhung voice coil. A three-part coil system has a lower winding height of the voice coil and therefore also a lower moving mass. In addition, the coil wire of the TESLA.45 driver with a diameter of 50 µm is even thinner than the wire of the STELLAR.45 driver. This enables a higher impulse fidelity and a more brilliant high-frequency reproduction. If you take a closer look at the diaphragms of the STELLAR.45 and TESLA.45 drivers, you will notice that their structures differ significantly.
Do you want to learn more about the STELLAR.45 driver? In the blog post: The new beyerdynamic driver in our PRO X headphones we provide deep insights into the creation and functionality of our STELLAR.45 technology.
Or do you want summarized information about our beyerdynamic transducers? From STELLAR.45 to Tesla technology, in the blog post The centerpiece of our products: The sound transducer you will find all the information.
Why does the TESLA.45 driver have 30 ohms?
Ante: When designing the TESLA.45 driver, we attached great importance to flexible use. One requirement was to develop a driver that works as efficiently as possible. This ensures playback at high levels even on playback devices with a low output voltage.
An efficient driver such as the TESLA.45 can generate a high sound pressure level with a low applied electrical voltage. The low electrical resistance (impedance) allows a high current and therefore a high driving force (Lorentz force) of the coil.
The exact figure of 30 ohms was not specified, but is the result of calculations aimed at achieving high efficiency and high impulse fidelity with low distortion. The specific resistance of the wire, the number of voice coil windings and the configuration of the magnet system are of critical importance.
The development and further development of Tesla technology is certainly complex. What challenges had to be overcome during development?
Ante: Developing new products like the TESLA.45 drivers brings many challenges, and that’s to be expected. Each part is designed from scratch and must function as a unit.
“When developing a new driver, we draw on the expertise of beyerdynamic’s 100-year history.”
Ante, acoustics engineer
It was precisely this harmonisation of the individual parts that was one of the greatest challenges in the development of the TESLA.45 driver. For example, there are interactions between the individual components that need to be recognised and resolved during development.
The main focus was on the development of the new diaphragm. With the help of FEM simulations, we simulated the acoustic and mechanical response of the diaphragm and optimised the diaphragm. The short iteration cycles in the simulation enabled us to speed up the development process and to investigate the properties of the diaphragm in detail. Regular validation using test set-ups confirmed the results of our simulations.
The transfer of drivers developed under laboratory conditions to stable series production in large quantities is an essential step in product development. beyerdynamic has developed production facilities specifically for the manufacture of this driver and readied them for series production.
Close interdepartmental cooperation was essential to the successful development of this product.