Sennheiser HD 820

Closed-back reference over-ear with Gorilla Glass reflectors and 56 mm ring radiator

Key features

• A new benchmark for closed-back audiophile headphones
• Convex Gorilla Glass reflectors deliver an astonishingly spacious presentation
• Ultra-ergonomic adjustable metal headband with internal padding element
• Designed in Germany and precision-built at Sennheiser’s state-of-the-art facility in Ireland
• Frequency response: 6 – 48,000 Hz (-10 dB)
• Dynamic transducer system with a 56 mm ring radiator
• Acoustic absorption system prevents frequency masking for surprising detail
• Microfiber padding for earcups and headband—exceptionally comfortable at key contact points
• Impedance: 300 ohms
• Total harmonic distortion: 0.02% (1 kHz, 1 Vrms)

Completely closed. Incredibly open.

The HD 820 combines our most advanced transducer expertise with exceptional noise attenuation—pushing the perceived limits of closed-back headphones.

Until now, the audiophile headphone experience was often defined by Sennheiser’s open-back designs, which shaped an entire category of precision listening. That standard could outperform exponentially larger and more expensive hi-fi systems—while accepting that listeners wouldn’t be isolated from their surroundings.

The HD 820 sacrifices neither detail nor soundstage: thanks to innovative acoustic systems, it delivers both in a closed, dynamic headphone.

Internal reflection

A closed-back headphone capable of creating the wide, natural soundstage of an open design requires rethinking the directionality of sound waves.

While sealed headphones offer maximum privacy, redirected energy can create resonance and distortion at the ear. The HD 820’s signature experience comes from precision concave glass reflectors—one per earcup.

Positioned on the outer plane of each ring radiator transducer, these plates reflect energy from the rear of the driver into a specially tuned absorption system—allowing wave behavior that can emulate open models like the HD 800S. Beyond the striking visual effect, the glass reflector enables a sonic spectrum rarely (if ever) experienced in a sealed headphone.

The ring’s companions

A remarkable aspect of the HD 820’s 56 mm ring radiator is that it leverages the key advantage of a large diaphragm—air movement—without losing the stiffness that benefits settling and response times.

There is no single mounting point on the outer perimeter, yet both the outer and inner edges of the ring are attached to the driver unit. The voice coil drives the diaphragm, linked to the V-shaped groove near the ring’s center.

A vibration-damping frame and an inert headband insert ensure total stability—delivering surprising speed and precision across the frequency spectrum. What goes into the HD 820 is exactly what comes out.

Each transducer is produced, tested, and measured to extremely strict tolerances for consistent performance from day one. Every HD 820 set also includes a frequency response chart tied to its serial number—no resources spared to help you retrieve the most critical details from every corner of your music library.

Precision engineering

The HD 820’s deep, almost magical stereo image reflects the meticulous design poured into every detail.

Designed in Germany and built in our state-of-the-art facility in Ireland, its build and finish are rivaled only by its sonic performance. Thanks to the ring radiator’s exceptional response and optimized driver angle, it becomes easy to pinpoint the right sound, the right instruments, and the right space.

Luxurious ear pads and progressive joint points provide isolation, eliminate distractions, and help you stay focused through long listening sessions. Whether for critical listening or private calls, the HD 820 prevents unwanted sound from getting in—or out.

An ergonomic pleasure

The HD 820 is built for long-term comfort—delivering an experience that’s as gentle as it is captivating.

Every contact point features exceptionally soft padding, while specially developed materials reduce weight and unwanted pressure. Each earcup uses a dual-axis hinge that adapts instantly and effortlessly to your head shape—so your passion for high-resolution listening is never held back.

It’s all about relationships

As the centerpiece of an ever-evolving system, your reference headphones must offer the versatility required to listen on your terms.

The HD 820 ships with a versatile set of essential cables, each optimized for ultra-low capacitance. The 6.35 mm (1/4") stereo plug is the audiophile standard for connecting to headphone amplifiers, DACs, and A/V receivers. The 4.4 mm balanced plug paves the way for a new generation of balanced-output devices, offering a compact connection that proves superior over time. An optional XLR-4 balanced cable is also available.

Each cable is 3 m (9.8 ft) long, allowing free listening whether your gear sits in a studio rack, on a shelf, or on a desk.

Technical specifications