Planar Magnetic Headphones with 85MM TPU

Planar Magnetic Headphones with 85MM TPU

The use of thermoplastic polyurethane (TPU) elements with 85 mm drivers is a new and innovative way to construct planar magnetic headphones. The most important findings reveal that the 85 mm diaphragm provides a solid blend of soundstage, bass extension, and comfort. Because TPU is strong and flexible, it is feasible to come up with novel ways to build things and generate sounds. Recent do-it-yourself projects have shown that you can get flat frequency responses from 11 Hz to 17 kHz with 85 mm speaker pads and TPU 3D-printed headbands. This shows that prototyping may be done with the help of customers. The Fostex T50RP series and other previous examples made it possible to build 85 mm planar diaphragms. New advances in polymer film technologies suggest that TPU-based membranes may be employed in the future alongside well-known materials like PET and PAR. This report talks about the physics of planar magnetic drivers, how the 85 mm form factor has changed over time, TPU's mechanical and acoustic properties, a case study of making headphones with 3D printing, and the future of using TPU in diaphragm materials and driver assemblies.

The Basics of Planar Magnetic Headphone Drivers

A gap between two magnets holds a thin, conductive diaphragm in place in planar magnetic drivers. When an audio signal goes via the electrical traces that are connected to the diaphragm, electromagnetic forces make it vibrate. This produces noise. Dynamic drivers, on the other hand, use a voice coil that is coupled to a cone-shaped diaphragm. The planar approach provides less distortion and a faster transient response because the stresses are spread out along the diaphragm. This lowers mass and mechanical resonances. Planar designs, on the other hand, usually demand bigger magnetic arrays and have higher impedance. This implies they need more powerful amplification. So, it's very crucial to choose the proper materials for the diaphragm and structural pieces to acquire the highest sound quality, sensitivity, and durability.

Examples of 85 mm driver formats from the past and present

Planar magnetic headphones have had the 85 mm driver size for a long time. For example, the Fostex T50RP series from the early 2000s is a nice one. The T50RP had an 85 mm diaphragm inside a rubber-sealed casing to make the bass sound better. Many people have made changes to it and made their own versions because of how it looks. Oppo's PM-1 and other newer versions for consumers have an oblong diaphragm that is 85 × 69 mm in size. This illustrates that this size range is still a reasonable approach to find a decent compromise between the size of the driver area and the size of the headphone enclosure. Drivers that are greater than 90 mm are common in modern open-back headphones. The a 90 mm planar diaphragm that makes the low-frequency response longer, while has a 97 mm driver that makes the soundstage broader. The 85 mm format is still popular, nevertheless, because it is a versatile platform that permits headphone designs go smaller without losing crucial components of planar magnetic performance.

Using Thermoplastic Polyurethane to Make Headphones

Thermoplastic polyurethane (TPU) is a flexible polymer that is easy to work with and can be created by injection molding and additive manufacturing. This makes it a good material for making headphones. Headband cushions, yokes, and gaskets in headphone assemblies are commonly made of TPU. This is because it can bend and stretch a lot without losing its shape, which makes it stronger and more pleasant for people to use. Because of the advent of TPU filaments in 3D printing, hobbyists and small enterprises can now design their own headband shapes. They can modify the clamping force and the contour of the headband to match their demands because TPU is flexible. TPU is also useful for gaskets and earcup seals since it absorbs sound. This stops sound from bouncing around inside and makes the bass response better in closed-back designs. As manufacturing technologies get better, TPU will change the microstructure of headphones, making it easier to create lattice-based frameworks that are both lightweight and strong.

DIY 85 mm TPU Planar Headphone Case Study

An example of TPU being used in the making of planar magnetic headphones is a DIY effort that includes an 85 mm planar driver inside a 3D-printed TPU headband and yoke assembly. The study utilized specialized testing equipment that replicated the acoustics of the human ear. From about 11 Hz to 17 kHz, its frequency responses looked flat. The builder used ear cushions that were 85 mm wide and cost less than six dollars. They also exploited TPU's strength to produce a headband that could bend without breaking and stay light. We didn't know what the diaphragm was made of, but the practical outcome revealed that the placement of the drivers and the design of the gaskets—made easier by TPU's ability to conform—can have a major effect on how deep the bass sounds and how well the whole tone is balanced. This study demonstrates that consumer-grade additive manufacturing and standard planar drivers can collaboratively produce high-quality goods without the necessity for conventional industrial equipment.

The future of TPU-Based Diaphragm Materials

TPU's natural properties make it a good choice for use as a diaphragm substrate in planar magnetic drivers as well as for structural purposes. Polyethylene terephthalate (PET), polyarylate (PAR), and PEEK are some of the polymers utilized to manufacture classic diaphragm sheets in planar designs. These materials were chosen because they are light, strong, and stable at sound frequencies. TPU has certain distinct advantages, such as higher elasticity, resilience to bending fatigue, and the ability to vary its hardness by changing the polymer chain's composition. It's hard to utilize TPU as a diaphragm film because it has to be thin enough to avoid mass loading and the conductive traces have to be evenly metallized. Research into film extrusion and micro-coating techniques may enable TPU diaphragms to rival existing materials. These new materials might be more resistant to tearing and last longer, but they would still preserve the planar driver's trademark low distortion and quick response.

Things to Think About and Future Directions When Designing

New types of magnets, 3D printing, and processing of polymer films are making it possible to make 85 mm TPU-integrated planar headphones. New magnet alloys with higher flux densities could make magnetic arrays smaller. This would make them lighter and more flexible, which is what TPU needs. Using strong TPU scaffolding and softer portions to ease pressure, multi-material 3D printing could make it possible to build headbands with variable levels of stiffness. Co-extruded TPU composite sheets with built-in conducting channels on the driver side could make assembly easier and let the product endure longer when it is put under mechanical stress. To acquire the proper amount of internal damping and leakage, it will be highly crucial to use acoustic modeling and finite element analysis (FEA) to improve the forms of TPU gaskets. As more open-source driver designs come out, it may be possible to get standardized 85 mm TPU-compatible housings. This would provide customers more options and make it easier for them to upgrade their systems.

Conclusion

The 85 mm planar magnetic driver format and TPU-based structural pieces work well together, making them a promising new field of headphone engineering. The Fostex T50RP and Oppo PM-1 are two examples from the past that indicate that 85 mm diaphragms can function. Recent DIY initiatives illustrate how TPU's flexibility and ability to be 3D printed can make building high-fidelity headphones easier. Most of the diaphragm materials are still PET and PAR films, but TPU's mechanical and processing benefits should be explored at more for both structural and acoustic usage. New advances in magnet technology, additive printing, and polymer science could make it possible to make a new kind of planar headphones that are light, strong, and can be customized. These headphones would use the best parts of both 85 mm driver geometry and TPU innovation.