April 2021

Sennheiser HD820 Closed Back Stereo Headphones Review
Following on from his review of the classic open-back HD 800 headphones from Sennheiser in the last issue of HIFICRITIC, Keith Howard now assesses the closed-back version HD 820.
Review By Keith Howard

  This is a rhetorical question because I don't pretend to have an answer to it. Why did it take Sennheiser so long, in the wake of the successful launch of the HD 800 in 2010, to develop a closed-back version? A glance at the HD 820 ($2399.95) is enough to tell you that that's what it is – but we had to wait a further eight years for it. Could it be that Sennheiser was diverted into serving the burgeoning mobile audio market? Or that developing a closed-back sibling to the HD 800 proved tough? Having spent a month measuring and listening to the HD 820, I reckon the latter is at least a realistic possibility. Because if you expect the HD 820 to provide HD 800-like sound quality (but with improved isolation of external sound), you're destined to be disappointed.

Much about the HD 820 is familiar from the HD 800 and later HD 800 S: the bold industrial design using advanced plastics and stainless steel; the 56mm ring driver, set at an angle to the ears; the D-shaped capsules with their thin but comfy earpads; the long, 3.4m cables terminated in a quarter-inch TRS jack for unbalanced connection or TRRRS Pentaconn jack for balanced operation. The only obvious difference, apart from the HD 820's higher price (L1999 versus L1400 for the 800 S), wooden presentation box and different colour scheme, is the concave transparent plastic circles which close off the back of the capsules while still allowing you to peek in at the drive units.

I listened to the HD 820 using exactly the same partnering equipment as with the HD 800 S in the last issue: a Teac HA-501 headphone amplifier fed analogue signals from a Chord Electronics QuteHD, itself fed S/PDIF from a TC Electronic Impact Twin FireWire audio interface, with a second-generation Mac mini running Windows XP and JRiver Media Center v19 delivering the music.

Perhaps the first thing to say about the HD 820's sound, referring back to the 'tweak' I suggested in the HD 800 S review, is that again I preferred the result with the dust covers removed from inside each capsule. I found the 820's sound to be a little more vital, a little more nuanced with them set aside, just as with the 800 S. But this is one of the few respects in which I find it easy to equate the two designs sonically. I don't want to be too harsh on the 820 because it's far from being a bad headphone, but comparisons with its open-back cousin do it no favours – unless, perhaps, you like its weightier bass, which I don't.

A Fine Head Of Bass?
On the subject of bass, it's worth making the point here – for readers who may be disinclined to read the Lab Report – that, in common with every closed-back headphone I've measured, the 820 is sensitive to the integrity of its earpad sealing, much more so than the 800 S. This means, in effect, that if you are bald or have very short hair and don't wear spectacles, you will hear a different tonal balance to someone with thick hair and/or chunky spectacle frames because earpad leakage may then pare back the 820's bass and lower midrange output, potentially by large degrees.

This always begs the question: for which circumstance did the manufacturer design the headphone? A perfect seal, or the more compromised seal that many users will experience? Whatever the answer to that in this instance (I suspect the latter given the 820's boosted bass compared to the 800 S) the unavoidable fact is that different users will experience different tonal balances from this headphone.

Above all else I demand two things from hi-fi equipment: that it be informative and engaging. In other words, revealing of both the recording and the musicianship. The two often go hand in hand, making the difference between an addictive experience and one which is uninspiring. It's in these respects that I find the HD 820 wanting.

I listened, of course, to some of the same pieces I mentioned in the 800 S review, like 'I've Got A Crush On You' (a 192kHz/24-bit rip from Sinatra At The Sands, Reprise 8122 73777-9) and Sabina Sciubba and Antonio Forcione's 'Take Five' from Meet Me In London (Naim label 192kHz/24-bit download). While I didn't have the 800 S to hand for direct comparison, it was obvious that the 820 served neither of them as well as its open-back sibling had.

Just Not There
Setting aside its bass excess (a bugbear of mine), it didn't give the same sense of 'being there'. The subtleties of the Count Basie Orchestra's contributions were less telling and the 'image' less spacious in the first case, while Sciubba's masterful changes of vocal delivery and timbre could easily be missed in the second. In analogue tape terms, it was like listening to a second- or third-generation copy master rather than the original. Some of the vitality had gone AWOL.

A lot more than 'some' of the vitality was missing when I played Doug McLeod's 'Black Nights' (from There's A Time, 176.4kHz/24-bit download from Reference Recordings), a recording which should stun with its sense of presence and spellbind with its musical directness. The 820's bass excess bloated both the double bass and the lower register of the acoustic guitar, and McLeod's voice was softened to the extent of depleting its raw emotional energy.

It wasn't only high-res demonstration pieces that were affected by the 820's lack of ebullience. Conway Twitty's 'Lonely Blue Boy' is nothing of the sort, instead an over-the-top rock and roll novelty with almost farcical vocal EQ. But it's huge fun, provided that its exuberance is allowed full reign. The 820 gave the impression of applying a deadening hand to proceedings, of being buttoned-up when, mixing metaphors, it should be letting its hair down.

It's often supposed that this sort of 'refined' delivery better suits classical music – but certainly not the sort of classical music I listen to, which craves resolution and neutral tonal balance at least as much as any other musical genre. So I wasn't surprised by this stage to find that the 820 – to cite just one example – did no favours to 'O Ruddier Than The Cherry' from Handel's Acis And Galatea (44.1kHz/16-bit rip from Great Operatic Arias, Chandos CHAN 3044). Both the song and John Tomlinson's performance of it captivated me when I first heard this in-car on Radio 3 – it was one of those instances when you carry on listening even though you've arrived home – but it was altogether less absorbing here. The string sound was thickened at LF, and the 820's lack of brio seemed to drag on what should be a jaunty, dance-like tempo.

To elaborate further would be pointless: I'd hoped for another transcendent headphone experience from Sennheiser, as with the 800 S – but the HD 820 just didn't deliver.

Lab Report
Uncorrected frequency responses for the two capsules, and diffuse-field-corrected and Harman-corrected responses (generated using the mean response of the two capsules) are shown in the accompanying graphs. Unlike the HD 800 S, the HD 820 has shelved-up bass output along the lines advocated by Harman but this begins higher in frequency than Harman's target response so the Harman corrected response shows a hump in the upper bass, followed by a suck-out in the lower midband. As a result the HD 820 achieves lower Harman Predicted Preference Ratings of 46%/52% (for the left/right capsules respectively) compared to 62%/68% for the HD 800 S. But from 250Hz upwards the Harman-corrected response is flat to within +/-4dB and the diffuse-field-corrected response to within ±6dB, which are good figures.

These responses all assume a good seal to the listener's head. If that isn't achieved – for instance, because of thick spectacle frames or because the headphone is worn over hair – the result is a significant loss of lower-midrange output and even larger losses in the bass, amounting at worst to around 15dB at 20Hz in my testing.

As with the HD 800 S, the uncorrected responses show an odd bass feature – here a marked dip in output around 65Hz – caused by a headband resonance. Elsewhere in the spectrum the cumulative spectral decay waterfalls for the two capsules (not shown here) evince only well-damped resonances above 1kHz, although – unsurprisingly – the HD 820 fails to match the exemplary performance of the openback model in this respect.

As a closed-back design, the HD 820 begins to provide significant isolation from external sound above 300Hz, achieving over 20dB attenuation above around 1kHz. As a result it achieves modest reduction in level of environmental sounds (aircraft cabin noise, car cabin noise) that are dominated by low frequencies. But as the 820 is clearly not intended for use on the hoof, it will normally be called on to block external sounds in the less challenging circumstances of domestic listening, where it will prove more effective.

Due to the 820's high impedance, which varies between 512 ohms at 69Hz and 327 ohms at 3.45kHz, voltage sensitivity is on the low side at around 107dB SPL for 1 volt at 1kHz. The upside of this high impedance is that frequency response is largely unaffected by finite source impedance, even a 30 ohms source resulting in only 0.27dB modification.

Full measurement results can be viewed at HeadphoneTestLab.co.uk.

Sennheiser's HD 820 stereo headphones are on sale at
Amazon for $1790 at this link.

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Specifications
Type: Closed back stereo headphones
Driver: 56mm Ring Radiator transducer 
Frequency Response: 6Hz to 48kHz
Impedance: 300 Ohms
THD: <0.02%
Sensitivity: 103 dB at 1 kHz, 1V
Cable: Detachable, 3 meters (9.8 feet) length
Weight without cable: 360 grams (12.6 ounces)
Included accessories: 3 meter cable with 6.3mm stereo plug (¼ inch), 3 meter balanced cable with 4.4mm Pentaconn plug, USB manual with frequency response plot, deluxe storage box
Price: 2399.95 (on sale at Amazon for $1790)

Manufacturer
Sennheiser Electronic GmbH & Co.
Voice: (877) 736-6434
Website: Sennheiser.com