Sennheiser HD 820 Review

There’s an old saying, when one door closes, another door opens…

You can switch that around and swap door for headphone in the case of Sennheiser’s 800 series of circum-aural driver-equipped cans.

So, it would go more like when one headphone opens, another headphone closes, which is the case with Sennheiser’s newest addition to the 800 series: the closed-back $2,399 USD HD 820.

It’s a major departure from the design of its older siblings the HD 800 and the HD 800 S, the former open-backed, dynamic-driver model having launched in early 2009 featuring “ring radiator” technology, the latter hitting consumers heads in 2016. The original 800 quickly became both a favourite and pariah among the headphone cognoscenti of the time because while it is incredibly linear-sounding and comfortable, it was often referred to as having an disarmingly honest presentation that many listeners claimed was fatiguing.

To address this perceived shortcoming the company released the open-back 800 S aimed at warming-up what had by then been cemented into the 800 legacy as an overly-accurate sonic signature. The fix appeased many and the 800 love affair endured with fans (I have to say that the HD800 – along with the Audeze LCD-3 – lit a fire under me when it came to headphones as it was one of the first high-end cans I had the pleasure of reviewing and I fell hard for its transparency to source which resonated with me. I also found it to be supremely comfortable for long listening sessions, beating out the LCD-3 by a noticeable margin in that category).

Two years after the 800 S and Sennheiser pounced back with the subject of this review: the closed-back HD 820. From a structural/visual-design standpoint it’s undeniably birthed from the same German DNA (ditto the same 300-Ohm, 56mm dynamic driver), only now the signature vented open-back look championed by the 800 and 800 S has been eschewed for smartphone-grade glass as part of the driver’s backing enclosure – meaning looks can be deceiving, because you’d be forgiven if you didn’t notice it was a closed-back right off because of the transparency of the glass – so close are the rest of the external build cues to the original 800.

Let’s talk quickly about the differences between open-back designs and closed-back ones which use contrasting approaches to dealing with the rearward energy-radiation of drive units. A headphone drive unit (or any transducer) sends as much of its energy backward as it does forward, so a closed-back design has to deal with that energy and the inherent resonances that come with it, completely changing the technical-design specifications of the unit and the materials chosen for inclusion in its manufacture, whereas in an open-back design that energy dissipates out into the ether, transmitting away from the listening point, negating further build compensations to deal with it. Here, Sennheiser nomenclature specifies in particular how they dealt with the issue: “Sennheiser Ring Radiator transducers are fitted with unique glass covers. Revealing the great look of the technical component within, this visually striking feature was actually developed wholly in service to the sound: The concave glass reflects the sound waves from the rear of the transducer to an absorber, which results in minimal resonance. Thus, the sound waves are effectively ‘gone’ like they would be in open headphones.”

Build Quality

Like all Sennheiser headphones I’ve listened to or handled, the 360-gram 820 (30-grams heavier than the 800 S) is a solid, thought-provoking and flawless design execution with incredible attention to detail in every aspect of construction. The 820, like its predecessors, is the antithesis of bling to me. They are all technical articulation: no aged, polished wood surrounds or gold highlights here for conspicuous eye candy. From the asymmetric one-sided driver-housing yokes, the hybrid metal/plastic headband with its plush faux-suede foam liner and very large, hand-sewn and deep-scooped soft velour/microfiber and synthetic leather earpads (like the 800 I have on hand, the 820 is not easy to get the best seal with because of the size of the earpads) to the flexible, now-familiar, woven cable cover of the three-meter, silver-cladded OFC cable and its gold-plated 1/4-inch plug, these cans look the business.

The gorilla-glass enclosure never showed fingerprints that I could ever see either, the detail revealed in the driver assembly housing through its clear back is striking in its meticulous layout down to the specialized hex bolts used internally. The 820 comes in a beautiful, fitted impact-foam lined, black-stained wood case and features a choice of three cables for the buyer: standard 6.35mm termination, Pentacon (4.4mm balanced) connector or an optional XLR4 plug. But, what about a 3.5mm adaptor for portable use? You’re out of luck, Sennheiser doesn’t seem interested in you trying to power the HD 820 with a mobile phone or dedicated DAP/mobile head amp.

Sennheiser Electronic GmbH & Co