Sennheiser HD820 Review - Flagship Closed-back Headphones

Review written by Andrew Park (@resolve)

This unit was sent to me on loan for evaluation by headphones.com. For another perspective, check out Ian Dunmore's (@Torq) review of the Sennheiser HD820.

Introduction

The Sennheiser HD820 has always been compared to its open-back counterpart the HD800s. The big question is of course, does it do what that very famous headphone has been able to do, just with a closed-back design. If the answer is yes, this is a very good reason for the price increase over the HD800s ($2399 vs $1699), because closing off the headphone means it's possible to use it in far more environments. But from my experience, the performance threshold for closed-back headphones has traditionally be much lower than what we should expect from similarly priced open-back headphones. This perhaps should temper our expectations a bit, and so in my mind if the HD820 is able to even come close to the HD800s for sound quality, I'd still consider it a win. The following review examines this question, aiming to determine if it's worth it to go for the closed-back version over the legendary HD800s.

Specs

• Driver type - dynamic
• Headphone type - over-ear, closed-back
• Impedance - 300 Ohms
• Sound pressure level (SPL) - 103 dB at 1 kHz, 1V
• Jack plug - 6.35 mm / 4.4 mm, XLR-4 (optional)
• Cable length - 3m
• Weight - 360g without cable
• Price - $2399

Sources

• iFi Pro iDSD -> Cayin IHA-6 (Balanced)
• iFi Pro iDSD -> SPL Phonitor X (Balanced)
• iFi Pro iDSD -> ZMF Pendant tube amplifier
• Mytek Liberty DAC

Build & Comfort

Just like the open-back HD800s, the HD820 has some of the best and most precise build quality I've ever seen. It might not be the most sturdy feeling headphone, but Sennheiser continue to produce some of the most refined headphone offerings when it comes to look, feel and comfort. The main change between the HD820 and its open-back sibling is the concave glass covering the back of the cup. The principle behind this closed-back design is that the concave glass will reflect any of the resonances and standing waves back at an angle, rather than directly towards to the ear.

The other key difference is that the pads are slightly more comfortable, being a bit thicker than on the HD800s, and as a result I find the HD820 to be even more comfortable. My ears don't touch the mesh on the inside of the cup due to the slightly deeper pads. This headphone is also fairly lightweight, coming in at only 360g. Clamp force is also minimal, never introducing any pressure points - it has the ability to just disappear on my head. In fact, I have no problems wearing the HD820 for the majority of the day, sitting upright at my desk while working - and very few flagship headphones are in that category for me.

Score: 9/10

Performance

The HD820 borrows the famous ring radiator driver design of the HD800s, but the big question on my mind when approaching this review has been does the HD820 achieve similar performance in a closed-back. The HD800s (and original HD800) has been a benchmark for technical performance for such a long time, both when it comes to soundstage and detail retrieval.

Sound Isolation

It should be noted that while the HD820 is a closed-back headphone, I don't find it performs as well for sound isolation as many other closed-back designs. When running my measurements on my test rig I couldn't help but hear the sine sweep as the measurements were taken. I had to double check that the seal was correct, but it was audible every time I ran the test. This is normally something that happens with open-back headphones. When wearing the HD820 without any music playing, it was also possibly to hear my computer fans faintly, while other closed-back headphones like the Focal Elegia isolate me more significantly. I still consider the HD820 to be a closed headphone because it does reduce outside noise to some degree, just not as well as others.

Detail retrieval

The HD820's detail retrieval is surprisingly good. I say surprisingly because I wasn't expecting it to get as close to the open-back HD800s in that department due to the closed design. Image clarity for individual instrument lines is impressive with superb structural definition and textural capability. I noticed this most strongly in the lower treble area. We'll get into tonality shortly but even at its default tuning, the HD820 is a headphone that - when compared with most other closed-back headphones - highlights information in the mix that you didn't know was there previously. I find the HD820 to do slightly better at detail retrieval than my go-to Focal Elegia, however this may also be aided by the extra sense of stage and instrument separation going on. The HD820 is also able to handle a bit of EQ to improve overall clarity for its frequency response enhancing the perception of the detail retrieval this headphone does have.

Score: 9/10

Speed & Dynamics

For sense of speed, tightness, and control, the HD820 does a reasonably good job. It's not on the level of a high performance planar and it's not punchy like certain Focal headphones, and it also loses a bit of that 'tightness' as a result of an increased bass response that bleeds into the mids a bit. But overall it does have similar capabilities to that of the HD800s. So while there is a certain amount of impact imparted by the dynamic driver's excursive capability, it's still more of a slap than a slam.

Score: 7.5/10

Stage & Imaging

This is the HD820's main selling point. The stage is quite spacious for a closed-back, and while it doesn't come close to that of the HD800s, I really think this is the main reason to look into this headphone. Image separation and distinction is also fantastic. The main problem with the stage and imaging, however, is that because of the HD820's tuning, certain elements of the mix sit too far forward. To be more specific, certain vocals and instruments that token midrange frequencies sound a bit too intimate, while the rest of the mix is appropriately placed at a farther distance away. So it doesn't have the most even distribution of imaging for the full frequency range, especially when it comes to the center image. I did notice that when I applied a bit of EQ to the midrange, this significantly improved the center image for those midrange instruments and vocals.

Score: 8.5/10

Timbre

I don't hear any major issues for the timbre, so it doesn't sound harsh and metallic, but at the same time it's also not as natural and 'euphonic' sounding as a ZMF headphone or biodynamic. I'm once again reminded somewhat of the HD800s' timbre where I'd place it slightly closer to the dry and analytic side of things, rather than the more rich and sweet side, but not enough where it's a problem. 

Score: 8/10

Tonality

These measurements were taken with the MiniDSP EARS rig, using both the HEQ and HPN compensations. This measurement system is not industry standard and should not be compared with other measurements that are. Note that there is a coupler artifact at 4.5khz that shows up on just about every headphone.

The following shows how these headphones measure relative to the HPN compensation, which is closer to a traditional diffuse field target and doesn't take the Harman bass elevation into consideration.

The following shows how these headphones measure relative to the HEQ compensation, which is based on the Harman target and does add a bass shelf. Headphones that show flat bass extension on this compensation will have more bass than headphones that show flat bass extension on the HPN compensation.

Tonality and frequency response is where the HD820 falters substantially. This is one of the strangest sounding headphones I've heard in a long time - at least as far as overall tonality is concerned. The interesting thing with the HD820 is that nothing sounds immediately out of balance. I don't immediately notice any inappropriate peak that I can point out and say "here's where the issues are". At the same time, even without looking at measurements, it's clear there's something a bit strange going on with the tonality.

To me the HD820 sounds both hollow and compressed at the same time - especially when comparing it to a number of other headphones I have on hand that I might consider to have a more 'normal' tonality, regardless of the target curve. For some reason I'm reminded of that feeling you get when you're speaking and need to clear your throat.

In any case, there are a number of major issues with the HD820's tonality that throw off how it sounds, at least to my ear. The first is that the upper bass bleeds a bit into the midrange with a substantial elevation that gets too close to 200hz. Then beyond that, there's a substantial dip at roughly 300hz. This causes that somewhat hollow character for certain tracks that token the full frequency range.

I think the idea here was that the dip was necessary as a result of closing off the cups, but it unfortunately has the consequence of throwing off the sound a bit. If the dip had been a bit closer to 200hz it may have been better for bass definition and distinction. In any case, this dip is only accentuated with the midrange bump that shows up between 700 and 1300hz. This is where the midrange overshadows the lower treble around 3khz, causing a kind of congested and compressed sound.

For treble frequencies there's nothing really to complain about. It's a bit sharp at around 6khz but not enough to warrant any concerns about sibilance or percussion compression issues. In fact, snare drums and cymbals sound great on the HD820 with excellent tonal balance and resolution throughout the upper treble as well. It could use a bit more air up top above 10khz, but as a closed-back, there's nothing wrong with where it's at.

For my taste, I wish that the HD820 had better midrange balance, and I find that to be the biggest problem overall. Other aspects of the frequency response aren't perfect, but I could live with them, including the extra bass energy for the mid and sub-bass regions. One other thing to note is that the bass response does change substantially when using glasses, but in this case when you do get a good seal, the bass sits even higher than the Harman shelf, so maybe breaking the seal to lessen the bass energy would actually be desirable.

Score: 5/10

EQ Profile

I wasn't happy with the HD820's default tonality, but I was also really impressed with its detail capability and instrument separation qualities. Moreover, I'm reminded of the many HD800 and HD800s users who also happily EQ their headphones. So I figured I'd provide my EQ profile as a starting point for anyone who already has an HD820, or is potentially looking into getting one. For my EQ I use Equalizer APO and the Peace UI.

The following is a somewhat careful starting point for anyone wanting to get into EQ. I don't recommend using Q values higher than 3, and in general it's best to only apply gentle adjustments so you don't throw off the balance that the headphone does have.

For the HD820 I find that this adjustment helps gain a bit of clarity, and while you could take the upper bass down further than I've done here, some will appreciate the somewhat 'u-shape' this EQ profile achieves, so I'll leave the rest up to listener discretion. When toggling this EQ on, I found that much of the HD820's detail capability shone through better, with more overall clarity. Additionally the stage didn't feel as disjointed, likely helped by reducing the midrange bump.

The one area to be cautious of in particular with the HD820 is again that dip around 300hz. There's a risk that elevating this region may introduce certain resonances that could intrude on the rest of the mix as well, so I urge a bit of caution when adding the elevation pictured above. With any EQ, use measurements as a guide, but confirm your preference with your ears.

The following shows how the HD820 measures on the MiniDSP EARS rig after the above EQ profile is applied. This measurement uses the HEQ compensation.

Applying the aforementioned EQ profile brings the HD820 somewhat closer to a more normal sounding tonality (at least to my preference). In some ways it almost looks similar to the tonality of the Dan Clark Audio Aeon 2 Closed, just with a bit less air above 10khz. It could be taken further by bringing the bass down a bit more as it does still sit above the Harman shelf taken into consideration by the HEQ compensation. So once again, just use this as a starting point, and see where additional adjustments take you.

Conclusion

While the Sennheiser HD820 does certain things like detail retrieval and soundstage extremely well for a closed-back headphone, I would only really recommend it to those who are willing to do a bit of EQ.

It seems like there are two distinct thought processes for how closed-back headphones should be priced in relation to their open-back counterparts. The first recognizes that closing off a headphone incurs substantial trade-offs and challenges that usually impact sound quality, and that the versatility gained by making it closed-back doesn't outweigh the sound quality cost that gets paid. We can see this thought process with the Focal Utopia compared to the Stellia, and the Focal Clear compared to the Elegia - where the closed-back counterparts come in at significantly lower price tags. The other way to think about it is that closing off the headphone warrants an increased price tag, because it's able to be used in a much wider variety of environments.

In my opinion, the HD820 doesn't succeed in enough ways as a closed-back for the latter thought process of a price increase over its open-back counterpart to make sense. With that said, for anyone looking for a lightweight, comfortable, closed-back flagship that excels at detail retrieval and instrument separation specifically - and is willing to do some EQ - the HD820 may fit exactly that purpose.

Score: 7.8/10

Check out the video review:

-By Andrew Park (@resolve)

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