Review written by @Chrono
Headphones provided on loan for review by headphones.com
The HD 820 is a dynamic-driver headphone designed for reference-class listening, and it is Sennheiser’s closed-back take on their own HD 800 S. The HD 820 builds upon the HD 800 S’s design by creating an enclosure that fits glass covers on Sennheiser’s Ring Radiator driver. The glass covers on the drivers are visually striking, but more importantly, they are the acoustic component around which the HD 820’s closed-back design revolves. The idea in this implementation is that the concave glass covers reflect sound waves from the rear of the driver towards absorbers that aim to eliminate resonances. The solution that the HD 820 offers for the resonance issues that closed-back headphones inevitably face is a very appealing and innovative one, but how does it perform in practice? Has Sennheiser succeeded in making a closed-back version of their legendary flagship headphone?
Sources and Music Used in Listening Tests
The Amplifier/DACs used in this review were the SPL Phonitor XE (with built-in DAC), Grace Design SDAC + Topping A90, and the JDS Labs Element II connected via USB to my desktop computer. For the listening tests I used music from a wide variety of genres including Rock, Jazz, Classical, Acoustic, Hip-Hop, and latin. I played tracks from my own FLAC library as well as from Qobuz streaming service played via Roon (exclusive mode).
What’s in the Box?
Within its ridiculously large box (a pointless thing to mention, but really, I was shocked by the size of the packaging. It measures 16”x14”x6”!) you’ll find another large Sennheiser box that houses the HD 820, an instruction manual USB, as well as three different cables. All three cables use a fabric coating, measure 3m, and use dual-sided ODU connecters for the headphone side. The only difference between them is the termination for the amplifier side: one of them terminates in ¼” single-ended, and then the other two are XLR and 4.4mm balanced.
Build Quality and Comfort
The HD 820’s design is in large part identical to that of the HD 800 S, with the only difference being that Sennheiser has enclosed the rear of the driver. Despite being composed almost entirely out of plastic, the build feels solid, and well-refined. None of the moving parts feel loose, and I have not heard any creaking. Overall, I feel like the HD 820 is very structurally sound, and does not feel like it would have any quality issues down the line. However, there is one element in this design that I do have a really big problem with–the ODU connector jacks on the HD 820.
I don’t like to admit it, but I did have an accident with an HD 800 S–which uses the same connector type–where the jack assembly came right off when I tried removing the cable from the headphones. This is because the socket assembly on the HD 800 S and HD 820 is only held in by friction and two very thin wires that connect it to the driver. When you combine that with the ODU connectors, which fit quite tightly in the jack, it is very easy to rip out the entire socket assembly if you are not careful with how you detach the connector. I hope that if there are future revisions of these two headphones, Sennheiser is able to introduce a reinforced design for the jacks on the headphone to prevent users from accidentally tearing them apart.
For comfort, the HD 820 is–like the HD 800 S–one of the most comfortable headphones I have had the opportunity to wear. For their size, they are remarkably lightweight at only 360g, which is only 30g heavier than the HD 800 S. The ear cups are extremely spacious, and because the pads on the HD 820 are thicker than on the HD 800 S, it’s even less likely that your ears will come in contact with the driver. For me, this is a headphone that easily disappears when wearing, and remains very comfortable even in day-long listening sessions.
Certain aspects of the Sennheiser HD 820’s sonic performance have really impressed me, as it has overcome a lot of the performance drawbacks I associate with closed-back headphones; a lot of the HD 800 S’s technical characteristics are still clearly present in this closed-back counterpart. As I will share briefly, though, it was also very clear in my experience listening to them that there were drastic concessions made–particularly in terms of tonality and frequency response–in order to maintain that level of technical performance.
Whereas the bass region can come across as lean, and somewhat sterile on the HD 800 S, I would describe it as being rather warm on the HD 820. Compared to the HD 800 S, the HD 820 has a very good level of presence in the sub bass region, and to me it sounds like its bass shelf under 100hz is similar to that suggested by the 2018 Harman Target Curve. I will note, though, that this sub bass presence is very subject to fit and seal. In my experience, I found that putting the HD 820 on in a position that was even just very slightly off would cause a lot of the sub bass to go away; and I imagine that for users wearing eyeglasses this effect is further amplified.
Moving closer towards the midbass, the HD 820 sees a significant rise at around 150hz which could make the bass sound occasionally a little bloated for me. However it sounded like it was a fairly narrow bump, so there was no bleed from the upper bass into the lower mids and I think that some listeners might really enjoy the warmth and fullness it introduces in this region of the frequency response. There’s only real quirk I heard when listening to they HD 820 is that there is a dip at around 70hz that can make the bass occasionally sound a bit disjointed, but altogether I actually think that the bass response’s tuning on the HD 820 is more enjoyable than that of the HD 800 S, as it isn’t as thin and does have a fair bit more extension. For detail in the bass, I feel that the HD 820–like the HD 800 S–is not quite as articulate or as well-textured in this region of the frequency response; it doesn’t strike me as having the tightness and control in the bass that headphones like the Focal Clear, LCD-X, and HEDDPhone have.
I tend to associate Sennheiser headphones with amazingly-tuned mids. After all, the HD 600 series is constantly praised for its midrange accuracy, and the HD 800 S also agreed to be very faithful in its reproduction of the midrange. Unfortunately, though, I can’t say the same for the HD 820.
The midrange on the HD 820 is, to me, really strange, and it is definitely what throws off this headphone’s tonality and timbre the most. To me, there seems to be a lack of tonal richness that is derived from a pretty severe dip at around 250hz-300hz that takes away the body for vocals, as well as many instruments of which fundamental tones lie in those lower registers of the midrange. This dip is made more apparent by an elevation that follows it at around 1000hz, unnaturally accentuating some of the overtones in the midrange, which makes vocals in particular sound, to me, a bit nasally. Lastly, there is a fairly wide recession in the upper midrange centered at around 4K that made the mids lack a pretty significant amount of presence.
For internal resolution and overall sense of clarity in the mids, I think that the HD 820 offers fantastic performance. In this regard it gets remarkably close to the HD 800 S’s and, for me, even slightly outperforms other exceptionally resolving headphones like the Audeze LCD-X and Focal Clear. Still, I feel like the poor balance in the mids and their hollow, dark, and congested tonality overshadows the detail retrieval capabilities of the HD 820.
The HD 820’s treble I think is actually really good, and well-balanced. With the HD 800, and occasionally the HD 800 S, the peaks at 6K and 10K could be a little bothersome, but I find the the treble on the HD 820 is actually quite a bit smoother, with the only very minor complaint I have being that I feel like there is a very small shout or forwardness at 5K, but it really is excellent otherwise. Resolution is, again, fantastic in the highs and in my opinion the HD 820 is able to rival some of the best open backs in the over $1500 price range. Cymbal crashes, splashes and harmonics are all reproduced with a good amount of air, and a pristine level of clarity that surfaces all the textural nuances in the highs.
Soundstage, Imaging, and Layering
Since its original introduction, if there is one quality that has always garnered praise for the HD 800 series, it’s soundstage; and thankfully, that quality remains very impressive on the HD 820.
Now, whilst it may not be as spacious as the HD 800 S, the HD 820 still provides one of the most open-sounding experiences I have listened to in a headphone. For soundstage width, the HD 820 easily outperforms many of the open-back headphones that I’ve listened to, like the LCD-X, Ether 1.1, and Focal Clear. Additionally, the imaging on the HD 820 is very precise; it very accurately determines the directionality and positions of sound with no gaps. Furthermore, the HD 820 retains the HD 800 S’s outstanding instrument separation. The different instrument and vocal passages are all distinguished incredibly well from each other, and they really make it easier to surface elements in complex passages that might feel slightly drowned out on other headphones. Overall, I have to say that from my experience, the HD 820 has the best soundstage I have heard in a closed-back headphone.
Dynamics is a category in which the HD 820 really falters. Despite feeling a little weightier lows due to its elevated bass response, the HD 820, like the HD 800 S, is still seriously lacking in excursive force. The HD 820 does have a very good sense of speed, and a nice top-end snap, but If you are looking for a headphone with a good sense of punch and slam, and a satisfying physical impact, then the HD 820 really won’t be able to deliver that.
As I mentioned earlier when sharing my experience with the HD 820 and its FR, I found that it had quite a few deviations that made it sound, to me, rather unnatural. With that being said, though, I do think that EQ can greatly help in alleviating the quirks that are present in the HD 820’s tonality and allowing the headphone’s technical performance shine through.
For me personally, in the bass region, I feel like there is just a little too much sub bass, as I prefer the level of presence under 100hz to be a little bit lower than that suggested by the 2018 Harman Target Curve, so I like to set a -1.5dB downshelf at 60hz. Additionally, I like to reduce some of the midbass warmth to tailor the bass response closer to my preference.
EQ curve applied to HD 820
Moving along to the mids–where most deviations are–I use a series of filters to restore the tonal balance in the mids. The first filter I use is a peak filter at 250hz that gives a lot more energy and body to the lower mids. I think that I would have wanted to push it more, but unfortunately after a 7dB boost the HD 820 sounded like it started distorting very slightly. Nonetheless, that’s still enough of a boost to where the mids no longer sounded hollow. I also like to reduce 1K very slightly, and boost the upper midrange to give midtones a presence that, to me, sounds more natural. If you are interested in trying out my HD 820 EQ profile, these are the settings I used:
- Low Shelf at 60hz, -1.5dB Q of 0.7
- Peak at 70hz, +7dB Q of 3
- Peak at 150hz, -7.5dB Q of 1.2
- Peak at 250hz, +7dB Q of 1
- Peak at 1000hz, -2dB Q of 2
- Peak at 4000hz, +5dB Q of 1.2
- Peak at 5000hz, -3dB Q of 3
The HD 820 is a very impressive closed-back headphone that I really enjoyed after EQ, but if I am being honest, to me it still feels like a proof of concept of what a closed back HD 800 S could be like. Sure, it is literally a closed-back HD 800 S, but in this current design implementation, I feel like it sees way too many compromises over the HD 800 S without fully realizing the versatility benefits and convenience that are usually attached with closed-back headphones. I think that if Sennheiser was able to further develop this glass and sound wave absorption closed-back design, and was able to create an iteration that does not require EQ whilst also improving isolation, the HD 820 would undoubtedly be one of the top headphones out there. However, as it stands today, there really seems to be no benefits when moving from the HD 800 S to the HD 820, and I struggle to think of a scenario in which I would find myself recommending or personally choosing the HD 820 over the HD 800 S.
Watch the video review here:
For an additional take on the Sennheiser HD820, check out Resolve's review on the closed-back flagship.