In general, conventional speakers emit sound from the center of a cone-shaped diaphragm. The emitted sound interferes within the cone, generating air resonance, which can cause irregularities in the frequency response, and due to the bowl shape, can produce time differences in the reproduced sound, leading to muddiness or distortion. On the other hand, in the case of a planar diaphragm, it radiates all frequency bands evenly from the entire surface without delay, which resolves issues such as sound time differences and interference. I believe planar speakers were developed by various companies because these features allow for more faithful sound reproduction.
Planar diaphragms have excellent phase characteristics, minimal energy loss, and can produce clear sound without distortion, which are advantages. On the flip side, securing the necessary rigidity and durability for the diaphragm is difficult. As a result, the diaphragm can become heavier, or the structure becomes more complex to solve the weight issue, making manufacturing difficult. Gradually, planar speakers disappeared for these reasons.
Currently, some manufacturers continue their own research and development and produce and sell evolved planar speakers. Our store handles two manufacturers: FAL and Teragaki Lab. Although their structures, materials, and manufacturing methods differ, the basic concept of the planar diaphragm is almost the same.
Here is the product page for FAL speakers.
https://www.exclusive-audio.jp/shop/products/list.php?category_id=16
Here is the product page for Teragaki Lab speakers.
https://www.exclusive-audio.jp/shop/products/list.php?category_id=35
FAL is a leading Japanese specialized manufacturer of planar speakers, and has been conducting research and development on full-range driven planar diaphragms with excellent phase characteristics for over 40 years. To achieve sufficient satisfying power from a full-range driven planar diaphragm, it employs the powerful N48 neodymium magnet, which is the strongest among permanent magnets. DuPont-made voice coil bobbins use double-wound silver wire on both the outer and inner sides. The diaphragm is covered with papyrus made from reeds on the surface of lightweight, high-rigidity polystyrene foam (strength comparable to concrete!) and the edges on both sides are clamped with artificial leather Excene to form double edges. To maximize the responsiveness and driving force, the frame is made of aluminum die-cast, which is lightweight and sturdy. FAL has resolved problems that were once considered weaknesses of planar diaphragms using its own unique methods.
With the above structure, it achieves both high linearity and efficiency as well as high input tolerance. The square unit shape is said to have better directivity than circular shapes.
In typical cone-type speakers, sound radiation angle is about 60°, whereas FAL flat drivers exceed 120°. As a result, the sound field is wider and the stereo area is vast. A major feature is that the stereo imaging does not easily shift even when positioned off the center between the left and right speakers. By using the entire diaphragm for reproduction, even small sizes can produce sufficient bass. The 148×128×55mm FLAT-C60 can match the bass performance of a 30–40 cm woofer. Accurate phase characteristics and excellent localization allow spatial expression that vividly reproduces the texture and depth of each instrument in ensemble performances or vocals, making it very popular among classical and jazz enthusiasts. Additionally, due to high efficiency, even low-power single-ended tube amplifiers can handle it energetically, making it recommended.
This is a story about speakers that employ planar diaphragms. Around the 1980s, major manufacturers such as Sony offered quite a lineup of such models.
In a conventional speaker, sound is emitted from the center of a cone-shaped diaphragm. The emitted sound interferes within the cone, generating air resonance, which can cause irregularities in frequency characteristics, and the bowl shape can lead to time differences in the reproduced sound, resulting in muddiness and distortion. On the other hand, in the case of a planar diaphragm, all frequency bands are radiated evenly from the entire surface without delay, eliminating issues such as time differences and interference in the sound. I believe planar speakers have been developed by various companies due to these excellent characteristics that allow more faithful reproduction.
Planar diaphragms offer advantages such as excellent phase characteristics, minimal energy loss, and clear sound without distortion. However, securing the rigidity and durability required for the diaphragm is challenging, which can result in the diaphragm becoming heavier or the structure becoming more complicated to address the weight issue, making manufacturing difficult, and gradually leading to their disappearance.
Currently, some manufacturers continue their own research and development to produce and sell evolved planar speakers. Our store handles two manufacturers: FAL and Teragaki Lab. Although the structure, materials, and manufacturing methods differ, the basic concept of planar diaphragms is almost the same.
Here is the product page for FAL speakers
https://www.exclusive-audio.jp/shop/products/list.php?category_id=16
Here is the product page for Teragaki Lab speakers
https://www.exclusive-audio.jp/shop/products/list.php?category_id=35
FAL is a leading Japanese specialist manufacturer of planar speakers, which has been researching and developing full-surface-driven planar diaphragms with excellent phase characteristics for over 40 years. To achieve sufficient power for the full-surface-driven planar diaphragm, they use the most powerful type of neodymium magnet, N48, among permanent magnets. The voice coil bobbin made by DuPont is hand-wound in double layers with silver wire on both the outer and inner sides. The diaphragm is made by covering lightweight, high-rigidity foam (with the strength of concrete!) with papyrus made from reeds, and the edges on both sides are sandwiched with artificial leather Exene to form double edges. The frame is made of lightweight, strong aluminum die-cast to maximize responsiveness and driving force. FAL has addressed the problems once considered weaknesses of planar diaphragms using unique methods.
Due to the above structure, they achieve both high linearity and efficiency, as well as high input tolerance. It is said that the square unit shape has better directivity than the circular shape.
In typical cone-type speakers, the sound radiation angle is around 60°, but the FAL Flat Driver exceeds 120°. Therefore, the sound field expression is wider, and the stereo area is vast. A major feature is that even in positions offset from the center between the left and right speakers, the stereo imaging is less likely to be skewed. Because it reproduces sound using the entire diaphragm, it can produce sufficient bass even at a small size. The FLAT-C60, measuring 148×128×55mm, is comparable to a woofer of about 30-40cm. The spatial expression achieved through accurate phase characteristics and excellent localization vividly reproduces each instrument in ensemble performances, as well as the texture and depth of vocal music, making it very popular among classical and jazz enthusiasts. Additionally, because it is highly efficient, even low-power single-ended tube amplifiers can handle it energetically, making it recommended.
