For audiophiles there wasnt any doubt: When it came to circumaural headphones the very best sound required an open back design. This axiom has now been rendered obsolete by the youngest member of the Sennheiser Audiophile Range: The closed dynamic HD 820 employ an innovative technology that makes them sound breathtakingly transparent and natural. Developed and made in Germany, they offer an incredibly realistic, natural sound field and also stand apart by the extraordinary attention given to every detail of their design. Their soft comfortable microfiber ear pads are hand crafted, providing excellent attenuation of ambient noise, while the robust metal headband includes an inner damping element. Get ready for an unparalleled listening experience. Developed and manufactured in Germany, the HD 820 is a closed, reference-grade audiophile headphone that a combines an innovative glass reflector and Ring Radiator transducer technology for a benchmark listening experience as vivid as it is uninterrupted. The HD 820 fuses Sennheiser's bleeding-edge acoustic capabilities with exceptional reduction of ambient noise. Until now, the audiophile headphone experience could only begin with an open back design or loudspeakers. The HD 820 sacrifices neither detail nor sound field by using breakthrough acoustical systems in a closed, dynamic headphone. The reference-class experience of the HD 820 is achieved with the use of precision concave glass reflectors, one capping each earcup. These functional plates reflect energy from the rear of the driver to a specially tuned absorber system, allowing the waves to mimic the behavior of open headphones such as the HD 800 S. The result is a sound stage never before experienced in a sealed headphone. The headphones vibration damping headband provides complete stability while reducing crosstalk. What you put into the HD 820 is precisely what you will get out of it. Each transducer is manufactured, tested, and measured to an extremely tight tolerance to ensure the most dependable performance out of the box. Each HD 820 also includes the frequency response plot unique to that sets serial number, sparing no resource to help you retrieve the most critical details from every corner of your music collection. The 56mm Ring Radiator transducer found in the HD 820 leverages the key benefit of a large diaphragm speakerair displacement. Both outer and inner edges of the ring are secured to the drive unit to keep it rigid for fast rest and response times. The result is accurate response spanning the entire frequency spectrum.