That makes a big difference to the listening experience. Closed-back headphones offer better isolation and a meaty mid-bass punch but sacrifice the openness and clarity of open-back headphones. Since their release back in 2009 Sennheiser’s HD 800 have been the go-to reference headphones for many audiophiles; can the HD 820 create their own legacy?
The Sennheiser HD 820 are arguably the best over-the-ear closed-back headphones to have ever existed. They’re as comfortable as the HD 800 and HD 800S, and they come with a convenient pack of three swappable 3.6m cables, terminating variously in a balanced 4.4mm plug, an XLR connector and an unbalanced 6.3mm jack.
But while the HD 820’s excellent design and sound characteristics can’t be denied, their sound can’t quite drop jaws like their open-backed siblings. Whether they’re right for you or not will, therefore, depend on your priorities.
Build quality, comfort and isolation
The HD 820 are visibly reminiscent of the HD 800 line, but they feature a new all-black design and a concave glass pane over the back of each ear. That’s Corning Gorilla Glass, so you needn't worry about scratches or accidental drops.
The glass cover has an effect on the sound, as I’ll discuss below, and it also provides much greater isolation than you’ll get from the HD 800 and HD 800S. It doesn't match up to the isolation of the Fostex TH900 MkII or the Audeze LCD-XC, but there’s certainly a lot less leakage than with its open-backed siblings.
One area where the family resemblance is particularly strong is the comfort. Like the original HD 800, the HD 820 are a pleasure to wear, even for hours on end. I wore them on an extended gaming session and didn’t experience the slightest discomfort, even while wearing my reading glasses.
The plastic and metal headband sits very lightly on the head, with a lovely soft microfibre fabric on the top and around your ears. The pads are twice as thick as the ones on the HD 800S, so they clamp on a little more strongly, and won’t fall off so easily when you’re headbanging to System of a Down.
The other notable design point is the proprietary connector on the outer edge of the headphones’ drivers, into which you plug your choice of detachable cable.
The HD 820 use a pair of 56mm dynamic drivers to deliver sound, and have the same 300Ω impedance as their open-backed counterparts. I tested them with a wide variety of listening material, using the balanced XLR output on a Sennheiser HDV 820 headphone amp, and the sound was simply fantastic all throughout the frequency range. I’d go as far as saying that these are among the most neutral-sounding closed-back headphones you can buy. Compared to the Fostex TH900 MkII and the Audeze LCD-XC, the HD 820 sounds less bassy and better balanced, without an overly warm signature.
Even so, the HD820 can’t quite live up to the near-perfect mid-range reproduction of the open-backed HD 800 and HD 800S. By comparison, they sound a little restrained in the lower mids at around the 300Hz region, while the upper mids feel a little boosted. A 1KHz boost was particularly noticeable in Baby D’s Let Me Be Your Fantasy (Platform 16 Remix), in which the vocals are slightly overpowered by the instrumentation.
Similarly, bass is excellent on its own terms. The HD 820’s low end extends brilliantly, with a controlled and precise mid-bass shunt. It’s a very refined sound, and a touch weightier than the HD 800 and HD 800S. Yet these drivers don’t provide the same level of excitement as other closed-back headphones. For example, the Fostex TH900 MkII’s Japanese cherry birch wooden cups provide a meaty sound to Chris Brown’s Loyal, while the HD 820 sound tame in comparison. If you enjoy a precise, heart-pounding bassline punch, I’d lean towards the Fostex.
One of the HD820’s strongest suits is its high-end reproduction. You’ll be rocking your head from side to side as you listen to Great Spirit by Armin van Buuren vs Vini Vici featuring Hilight Tribe. Like their open-back siblings, the HD 820 provide an exceptionally clean and crisp treble response that isn’t fatiguing on your ears – and there’s not a hint of the sibilance that afflicted the original HD 800.
For me, though, the HD 820’s most impressive trait is its soundstage reproduction. It’s wide and deep, thanks to those large drivers, and presents really excellent instrument separation. Positional cues in games are exceptional; the instruments and vocals in Bruno Mars’ Locked Out Of Heaven were pinpoint flawless. Naturally, the HD 800 and HD 800S sound even wider and airier – it’s what differentiates open-back and closed-back headphones – but the HD820 comes amazingly close for a closed-back design.
I also tested the HD820 with Chord’s Hugo 2 headphone amp, via an unbalanced 6.3mm connection, but this didn’t provide the same degree of detail as Sennheiser’s own offering. Clearly, like its predecessors, the HD 820 perform best when paired with the right amp and DAC.
The HD 820 deliver exactly what you’d expect from a closed-back variant of the HD 800S. They’re supremely comfortable, they produce an impressively neutral sound, and they offer better isolation than their open-backed siblings.
If you’re looking for an excellent soundstage, near-flat sounding mids, and some form of isolation from the outside world – and you’re willing to pay for the privilege – then you’ll struggle to find better than the Sennheiser HD 820.