HD 820 – The critics said closed headphones could never sound as immersive as their open-air counterparts. They said physics would never allow it. To that we simply said, “listen”. The HD 820 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 our cutting-edge transducer capabilities with exceptional ambient noise attenuation, transcending the perceived limits of closed headphones. Until now, the audiophile headphone experience could only begin with Sennheiser’s open-back design—a design that paved the way for an entire class of precision listening devices. This standard of sound reproduction would go on to surpass hi-fi systems exponentially larger in size and cost with the understanding that listeners would not be isolated from their surroundings. The HD 820 sacrifices neither detail nor sound field thanks to its innovative acoustical systems in a closed, dynamic headphone.
A closed-back headphone able to produce the wide, natural sound field of an open one requires rethinking the directional characteristics of sound waves. While sealed headphones offer the utmost privacy, redirected energy can create resonance and distortion within the ear chamber. The reference-class experience of the HD 820 is achieved with the use of precision concave glass reflectors—one terminating each earcup. Located on the outer plane of each ring radiator transducer, this functional plate reflects energy from the rear of the driver to a specially tuned absorber system, allowing the waves to mimic the behaviour exhibited in open-air models such as the HD 800S. While also a striking visual feature, the technical execution of the glass reflector yields a sound stage never before experienced in a sealed headphone.
An achievement in its own right, the 56mm ring radiator found in the HD 820 leverages the key benefit of a large diaphragm transducer—air displacement—without losing the rigidity that favourably impacts rest and response times. Instead of a single attachment on the outer circumference of the transducer, both outer and inner edges of the 'ring' are secured to the drive unit. The voice coil vibrates the diaphragm, connected to the V-shaped groove found near the centre of the ring.
The headphone’s vibration-damping chassis and inert headband insert provide complete stability, resulting in astonishing speed and accuracy throughout the entire frequency spectrum. What you put into the HD 820 is precisely what you will get out of it, too. 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 set’s serial number, sparing no resource to help you retrieve the most critical details from every corner of your music collection.
The deep, almost magical stereo imaging of the HD 820 is the sum of the exhaustive engineering poured into it. Developed in Germany and crafted at our state-of-the-art Ireland plant, its fit and finish is second only to its sound quality. When combined with the ring radiator’s superlative response, the driver’s angle allows you to locate voices, instruments, and their inherent environments. The sound field expertly balances realism and escapism, transporting you to the heart of your favourite recordings and nowhere else. The luxurious ear padding and progressive articulation points form a satisfying seal, eliminating distractions for added focus during extended listening sessions. For critical listening tasks and private listening alike, the HD 820 prevents unwanted sound from coming in or bleeding out.
The HD 820 delivers on long-term wearing comfort too, providing a listening experience as plush as it is immersive. Every contact point utilizes ultra-soft padding, while purpose-built composites reduce weight and unwanted pressure. Each earcup provides dual-axis articulation that instantly and effortlessly conforms to your head’s unique structure. The result is a listening session that never gets in the way of your passion for hi-fidelity sound reproduction.
As a centrepiece of your constantly evolving rig, your go-to headphones should offer the versatility to listen on your terms. Your HD 820 comes with a versatile set of essential cables, each one impedance-matched with ultra-low capacitance. The ¼-inch / 6.3mm stereo connector offers the audiophile-standard plug for connection to devices such as headphone amplifiers, DACs, and A/V receivers. A balanced 4.4mm connector opens a pathway to a newer generation of balanced output devices (headphone amplifiers, digital audio players, etc.) that embrace this compact plug’s superior stability over time. An optional XLR-4 balanced cable is available, providing yet another popular connection to a wide range of audio components. Each cable is 9.8ft / 3m long to accommodate unencumbered listening from devices anywhere on your shelves, in your studio, or on your desktop.
| Impedance | 300 Ohms |
| Frequency response (Headphones) | 12 - 43800 Hz (-3 dB) 6 - 48000 Hz (-10 dB) |
| Sound pressure level (SPL) | 103 dB at 1 kHz, 1V |
| Ear coupling | around the ear |
| Jack plug | 6.35 mm / 4.4 mm XLR-4 (optional) |
| Cable length | 3m |
| Weight | 360 g without cable |
| Transducer principle (headphones) | dynamic, closed |
