Sennheiser’s new HD 820 closed-back headphones will shake up the audiophile world

The 820 is a closed-back variant of the 800 S, adding a measure of isolation between your music and the surrounding environment. The original 800 S is like a sieve when it comes to letting outside sound in, and it pushes almost as much volume out of the headphones’ sides as it does into your cranium. There’s good reason, however, for this antisocial open-back design.

Closing off the acoustic chamber around your ear complicates a headphone’s design and threatens the purity of its sound by creating undesirable resonances and reverberations. That’s why we usually see open-back headphones like the 800 S or the Focal Utopia competing for the title of having the best and most pristine sound.

Sennheiser’s taken an exotic approach to crafting a closed 800 S. The company has chosen to put glass covers on the exterior of the HD 820, thereby retaining the signature exposed metal look of its flagships without actually exposing the audio drivers. Plus, Sennheiser claims the subtly curved Gorilla Glass cover helps reduce resonance by reflecting unwanted sound waves into special absorber chambers.

Axel Grell, Sennheiser’s longtime chief headphones engineer, isn’t shy about talking up the company’s latest product, saying that “the HD 820 is a game changer that delivers exceptional sound while insulating the listener from their environment. I consider them to be the most transparent-sounding closed-back headphones in the world.” Grell’s pursuit of transparency is another way of saying that these new headphones re-create the music exactly as it was recorded and intended, not putting any tint on it or spoiling its clarity.

Among the smaller changes Sennheiser has made with the HD 820 are new ear pads, which are a mix of synthetic leather and microfiber, created with the express purpose of helping insulate the listener from the outside world. Sennheiser is also adopting the 4.4mm Pentaconn balanced connector, which has been promoted by Sony as the next audio jack for enthusiast headphone makers to rally round. It is a little larger than the traditional 3.5mm audio plug, but provides balanced audio for minimal distortion.

The Sennheiser HD 820 headphones will go on sale in early summer 2018, costing an eye-watering €2,399 in Europe or $2,399.95 in the US. Their first exhibition is at CES in Las Vegas.