Sennheiser HD 620S Closed-Back Headphones - Official Discussion Thread

[taronlissimore]

This is the official place to discuss the new Sennheiser HD 620S Closed-Back Headphones.

Sennheiser Press Release

The new HD 620S breaks from the pack with contemporary tuning and soundstage that defy the closed headphone category.

Wedemark, Germany, May 8th, 2024 **
– The Sennheiser brand today unveiled the freshest member of the acclaimed HD 600 series, offering audiophiles a compelling take on closed headphones for private, reference listening without compromise.**
​​
​“The hi-fi community has clamored for a headphone with the best traits from our 600 series, yet isolates them from distractions at work, home, or in-between,” said Audiophile Product Manager Jermo Koehnke. “Not only does the HD 620S deliver on that promise, its immersive imaging and brilliant impulse response make it an exceptional listening experience for every situation where a higher level of performance matters.”
​

The family tree
​At the heart of the HD 620S is a custom-tuned 42mm dynamic transducer made at the brand’s state-of-the-art Tullamore, Ireland transducer plant. It carries forward the smooth and effortless sound found in the open-back 600 family with a modern, airy signature that balances honesty with deep and articulate bass. Thanks to a high damping factor, the 150-ohm aluminum voice coil excels at speedy transients and well-defined instrument tails for punchy dynamics across the entire frequency spectrum—a boon for audiophiles and passionate gamers trying to consume as much detail as possible in a given moment.

Situated in an iconic chassis beloved by audiophiles, gamers and streamers alike for its long-term wearing comfort, the HD 620S elicits a sense of confidence while providing an instant sweet spot. Metal appointments not only feel great to the touch but serve an acoustic purpose as well–the steel plate closing off the back volume is an efficient isolator that manages the internal reflections that cloud the purity of an acoustic signal within. The angled baffle is remarkably open to encourage the free movement of air, modeling the behavior of open-back transducers while recreating the triangular imaging of a great loudspeaker setup in an expertly tuned room. This immersive presentation drops the listener into the center of the action with impressive cue location, whether it is a rare live concert recording or massive online multiplayer showdown.

Case closed
​Open headphones are an audio purists’ favorite, however closed headphones are invaluable for listening when isolation from the world around the listener is essential. Audiophiles are accustomed to trading the natural response and wide imaging of open headphones in order to keep distractions at bay, or from disturbing roommates, spouses and coworkers. No doubt, the ​ HD 620S is a breakthrough in real-world performance, offering the dramatic soundstage they want absent the fatiguing, boxy sound associated with sealed cans.

You have new connections
​The HD 620S was built to last with a metal-reinforced headband and earcup housings. An included storage pouch keeps dust at bay with ample space for the detachable cable too, for tidy keeping. The 1.8 meter / 6 foot cable terminates to a single-ended 3.5mm stereo plug with an integrated locking screw for the included 6.3mm adapter. Available this summer, an optional balanced 4.4mm cable will let audiophiles tap into a growing range of hi-fi devices supporting the popular connector. The HD 620S shares the twist-and-lock single-sided cable design with other Sennheiser headphones, giving the user plenty of aftermarket options including different lengths and an in-line microphone.

Pricing and availability
​The HD 620S is currently available for pre-order, and begins shipping on June 6th 2024 with an MSRP of $349.99 USD/ $499.95 CAD.

Frequency Response Measurements from Sennhesier

[jlemaster]

Excited to see Headphones.com reviews when they become available, presumably on Launch Day. There is brisk interest on Head-fi [Unveiled: Meet the HD 620S | Headphone Reviews and Discussion - Head-Fi.org], one fairly detailed written review https://diyaudioheaven.wordpress.com/headphones/measurements/brands-s-se/hd620s/, and building excitement. I’m planning to pre-order and will post impressions here.

[jlemaster]

Thanks @Resolve and DMS for the great review that dropped today. Pls @Resolve would you be so kind to post here the EQ recommendations here (frequency, dB and Q) that you recommend for these (having mentioned that in your review). Also, in the interest of clarity, pls SOMEONE ANYONE define for me the meaning of “boxy” with respect to mid-bass performance. The image suggests listening with a box over your head, suggesting bass imaging that is reflecting off a wall a foot or two away…is that it? My headphone repertoire is fairly limited, I don’t have any that I would describe that way. Also, it seems like a technicality rather than a FR characteristic, but it seems it may be to some degree correctable with EQ? Pls help me understand.

[listen_r]

Hey there! I’ve gone ahead and taken an EQ profile @Resolve made for the HD 620S and both changed the measurement to include the results from other heads with DF-calibration, as well as revised the EQ moves slightly. Go ahead and give this a shot and see what you think!

Preamp: -3.9 dB
Filter 1: ON PK Fc 21 Hz Gain 4.0 dB Q 0.300
Filter 2: ON PK Fc 120 Hz Gain -5.0 dB Q 1.400
Filter 3: ON PK Fc 225 Hz Gain 2.7 dB Q 2.000
Filter 4: ON PK Fc 525 Hz Gain -2.4 dB Q 1.400
Filter 5: ON PK Fc 1510 Hz Gain 2.0 dB Q 1.400
Filter 6: ON PK Fc 2700 Hz Gain -1.5 dB Q 3.000
Filter 7: ON HSC Fc 8000 Hz Gain -4.0 dB Q 0.700

[jlemaster]

Wow this is fantastic. Thanks! 620s is shipping from headphones.com today. I promised Head-Fi a review w/o EQ but will add this in as well. My plan is to cp A/B to the HD6XX SE from the Chord Mojo2 since they can both be plugged in to each port at the same time to allow rapid comparison back and forth (as long as there are not volume matching issues between them which given the different impedance there could be).

Btw - not familiar with this nomenclature but assume these are all peak adjustments except the last which is a high-shelf, correct?

[listen_r]

Sounds like a plan! And yes they’re all peaks except the last which is a high shelf. Feel free to play around with gain values as needed!

[Zilax002]

Awesome. Thanks much! Will be excited to try the EQ next week after getting some time with the headphones next week.

[Zilax002]

I’ve never understoood what’s meant by “boxy” either. Maybe I will when I get the 620s tomorrow but I’m not holding my breath!

[generic]

@jlemaster

Also, in the interest of clarity, pls SOMEONE ANYONE define for me the meaning of “boxy” with respect to mid-bass performance. The image suggests listening with a box over your head, suggesting bass imaging that is reflecting off a wall a foot or two away…is that it?

@Zilax002

I’ve never understoood what’s meant by “boxy” either.

@jlemaster – that’s not inaccurate. A boxy speaker resonates in the same frequency range as a cardboard or plastic box. Metal boxes may be brighter and harsher (or not). Stick your head in a box or tap on a box and listen.

See this DIY Audio Heaven chart:

Lots of other info and charts here:

How to understand speaker measurements — and why they matter

[exactom]

Thanks for this I am new to equalizer apo and this really made it easy. I never felt an urge to eq but the 620s just sounded a little off to me and I love the form factor so much I wanted to make it work. These settings sound so much better and give me a reason to tinker with my other headphones. Thanks listen_r but also no thanks because I am staring down a new rabbit hole.

[listen_r]

I’m glad it helped make the headphone more enjoyable, especially since you like the comfort so much!

Apologies for starting you down the rabbit hole

[Zilax002]

I’ve been listening to the 620s almost exclusively for the last week. It is a very solid headphone, in my opinion.

The comfort is standout on my head (relatively light, clamping force that creates a good seal but doesn’t put enough pressure on my head to cause discomfort, like the other 6XX series headphones do).

Isolation is very good as well, in both directions. At modest to loud volume, I had to put my ears inches away from the cups to hear anything in our apartment with a fan at “low” setting on.

Pros:

• Out-of-box tuning is very competent, with excellent to okay performance across genres. (Will discuss EQ’d performance below).

• Light weight, “just right” clamp force. For reference, I tend to have more comfort issues from weight (Audeze, my man) than clamp, though there’s certainly a point where clamp becomes a real issue for me (HD6XX series, some Hifimans). The 620s really works for my head; I am only marginally aware that it’s “there,” and this has born out during several multi-hour listening sessions.

• A good closed back at an affordable price! This is hard to find, in my experience. The closest I’ve come prior to the 620s were the Audeze Maxwell and DCA Aeon Closed X. The Maxwell is too heavy and I find it “dead” sounding (lack of dynamics?). I like the DCA more; it has an excellent tuning with a similar weight and comfort profile to the 620s, but I cannot get a good seal with my head and beard (not to mention throwing glasses into the mix). The result: just absolutely no bass. Oh yeah, and then there’s the same lack of dynamics the Maxwell suffer from, but worse. (Side note: I can actually see an argument for the lack of dynamics not being that much of an issue, when you look at the headphone as a casual, all-day, listen while you work kind of deal. Which I can get onboard with! But the seal issues and the low sensitivity make it a less appealing option for a work phone to begin with. I haven’t checked recently, but I think the sound isolation was also not very good (not surprising, really, since I can’t get a good seal to begin with).

Cons

• Slightly unusual timbre on some tracks. This isn’t always evident, but it comes out on some tracks.

• Can sound a little “light” and “bodyless” on some tracks. (Perhaps a result of the “tucked” transition between bass and mids?)

My general user experience of the 620s, not EQ’d, is of a headphone that tends to sound “pretty good” (not necessarily exceptional), but every now and then a song will come on that gives me pause, though I’m not always sure why.

With EQ

I used @listen_r 's recommended EQ with one modification: at 8khz, I have a -2 high shelf, rather than -4.

A/Bing the two, volume matched using Equalier APO, I didn’t immediately feel a large difference between the two, though there was nothing objectionable in the EQ’d sound that I disliked.

After spending more time with the headphones, I can indeed hear the “boxiness” reviewers have mentioned. It’s not always evident, but in tracks where it manifests, the EQ’d 620s sounds tangibly more natural and clear.

TLDR: I’m really enjoying the 620s. Props go to the comfort, in particular, and to a tuning that generally sounds very competent and enjoyable. I haven’t really addressed “technicalities” much but, subjectively, I also find the 620s fairly good. The trailing ends of tones, in particular, sound more clear to me on the 620s than on many other headphones, regardless of price. The “soundstage” is wide and natural enough that I’m not overly reminded that this is a closed back.

There are no glaring issues out-of-the-box, and slight EQ adjustments have addressed the few issues I had with the stock sound.

I think I’ll be good with regards to closed backs for some time now, and the 620s near-perfectly fulfill the role of “I want a closed back headphone, but I don’t want to spend an absurd amount on one.”

[Dillpickleschmidt]

I’ve been using these headphones for about a week. I just managed to get an EQ that I really like so I thought I’d share.
Preamp: 0 dB (no preamp)
Filter 1: ON PK Fc 21 Hz Gain 2.0 dB Q 0.300
Filter 2: ON PK Fc 120 Hz Gain -5.0 dB Q 1.400
Filter 3: ON PK Fc 225 Hz Gain 2.7 dB Q 2.000
Filter 4: ON PK Fc 525 Hz Gain -2.4 dB Q 1.400
Filter 5: ON PK Fc 1510 Hz Gain 1.0 dB Q 1.400

That’s it

I started with the settings @listen_r posted, but I found that it killed too much of the high end and the bass was too boosted for my tastes.

To explain where I’m coming from with these settings, I’m someone who primarily listens to a pair of great desk loudspeakers that have some of the best tweeters I’ve ever heard (they’re paired with a sub), and I wanted a pair of headphones that wouldn’t make me die inside every time I had to deal with them instead of my beautiful loudspeakers. The soundstage was important in my purchase, but I needed a pair of closed-back headphones for work, so I went with the 620S.

I had been using the Sennheiser Momentum 2.0 over-ear headphones for years, and I liked them but the bass has fallen off over the years as the cups have eroded, and I wanted better treble anyway.

1 year ago I purchased the Momentum 4.0 and the bass was ridiculously loud so I returned them immediately. It was very deep but just not at all a flat response.

When I received these 620s a week ago, when I put them on, the first thing I immediately noticed was the boxy sound. I had heard that they might have a “subtle” boxy sound but when I tried them on for the first time, it was kind of shocking to me how boxy they sounded. The low mids were just so much less prominent compared to my loudspeakers that I took the headphones off after just an hour of using them. I almost returned them on day one.

However, I suspected that I likely needed to break in the headphones, as some of that cheap boxy sound might be attributed to that.

A week later, I think breaking them in has helped a lot. Maybe the drivers have loosened up, and maybe I’ve just gotten a little more used to them to the point that I don’t notice it as much. I’m still a/b comparing with my speakers and I certainly don’t feel like they sound as bad as when I first bought them. Whether that’s my subjective tolerance to their sound or the objective loostening/de-stiffening of the drivers, I can’t be sure.

However, the boxy sound is certainly still there, though lessened, so I figured I’d try EQ. I’ve always been very hesitant about EQ. My dad has a home theater (5.2 channel + low-tuned subs for seat shakers given a concrete floor) with all sorts of fancy EQ tricks to achieve a measured flat response but it invariably sounds better to me with most of that stuff bypassed. I run my stereo speakers with flat EQ except for a bump at 55hz (just under the 57Hz port tuning of my loudspeakers). I’ve tweaked my sub to be as unnoticeable as possible but I felt like it was a bit weak so the bass bump helps add punch to the lows while keeping the frequency crossover unnoticeable. All of this is to say that I’m not averting bass, I like bass, but I don’t like it sounding unnatural.

Back to the 620s headphones, the bass was sounding… weird. The treble (5-20k) actually sounded very nice. Not as smooth as my loudspeakers, but still has a very nice tone and sparkle, albeit a little less dynamic. Definitely a big upgrade from my Momentum 2.0 and a closer match to my loudspeakers.

I expected the bass on these headphones to be deeper given the graphs I saw, but it just wasn’t. In a good room with tall ceilings, my cheap subwoofer sounded deeper/better (I have a cheap 14inch $200 sub paired with my expensive loudspeakers).

So that brings me to the EQ settings. I’m aiming to match my loudspeakers, and, as a side note, my loudspeakers’ treble and mids sound balanced similarly to my dad’s Tesla Model 3, relative to the rest of the mix (both without EQ), so I’d like it to sound like that too. I actually have a little more bass from my subwoofer than the Tesla with the bump I put around 55hz, so I suppose you could say I like a little more sub-bass.

When I applied the settings from @listen_r , the first thing that I immediately noticed that the treble was killed. It just sounded too muffled, especially compared to my loudspeakers and the Tesla. By default, I find these headphones have nice treble, so I removed the high cut (filter 7) and the 2.7khz cut (filter 6).

The re-added sparkle brought life back to the headphones, and I could tell that the “boxy” sound was significantly improved with this EQ, but the bass was just too much so I couldn’t make any clear observations about that issue yet.

The next step was to fine-tune the bass. Right now, they sounded halfway between the stock 620s and the stock Momentum 4.0 (which are way too bassy), so overall still too bassy. I only cut filter 1 from 4db boost to 2db boost and that made a LOT of difference. The initial 4db boost felt like more of a preferential choice rather than a “fix”. Reducing it to 2db felt just right to me, and matches my subwoofer quite nicely. A 2db change at 21Hz seems small but sounds totally different.

I kept the -5db at 120Hz untouched. It’s definitely needed given the bump these headphones have at that frequency.

I also left filters 3 and 4 untouched. Since I removed filters 6 and 7, I toned down filter 5 by 1db which sounded very slightly nicer to me for some vocals.

Now, the missing sub-bass has been fixed, the boxiness has been reduced, and it maintains its initial clarity and sparkle.

Before I got to this point, with the mindset of using EQ sparingly, I initially did have the treble changes removed but the bass changes were halved (i.e. filter 2 was at -2.5db instead of -5db). It was still boxy and hardly different from the factory sound. You really need the full bass changes introduced by @listen_r (except filter 1 which I kept halved) to fix the boxiness sound.

In the end, though, I’m pretty happy with how the sound has improved, even with these subtle changes. The boxiness is still somewhat there, but it’s been significantly reduced given break-in time and EQ, to the point that I’m not picking up on it at all when casually listening.

*Just to clarify, simply listening for a week removed about 50% of the boxiness issues, EQ has fixed another 35%. So I’d say the boxiness issue is now only 15% as bad as my initial impressions, but that’s not bad at all for this price point, especially considering they’re headphones. The sub-bass also sounds a lot better too so that’s cool.

TLDR: The initial boxiness of these headphones disappointed me, I like to use EQ sparingly, I’m trying to match the balance of these headphones to loudspeakers 7x the price, I’ve managed to resolve most of the boxiness issues, I’ve tuned the sub-bass, and this is the EQ that sounds nicest to me.

If you’re looking for a song to test the frequency balance of these headphones, I recommend Hotel California but from the live “Hell Freezes Over (Remastered)” album. It’s a relatively full yet smooth mix covering a broad range of frequencies which is good for listening to/fixing that boxy sound. The kick drum is super deep too which lets you enjoy the bass improvements from this EQ.

If you old guys want to be adventurous, COLORs by SawanoHiroyuki also stress-tests the boxiness sound on these headphones. I also enjoyed the bass boost in this song provided by the EQ changes. The bass is really punchy and it really lets these headphones shine after they’ve been tweaked.

[hm42]

After couple of weeks I’m beginning to dislike the 620s more.

The uneven clamp force is pushing more at the top of the pads, touching the earlobes.
The cheap plastic pad coating with thick foam make me feel like I’m using bad Peltors, probably would be sweating on warmer days.
From comfort point of view I’d compare these with 5 series, not 6. Should be half the price as such.

Soundwise and without EQ they don’t sound exceptionally bad, just very dull. Soundstage is not very wide, the feel is like other equally priced closed back phones ie not very good.
So not a total failure but at this price point nothing to write home about.
I’ll continue looking for better sub $500 closed back headphones and sell these when something better pops up.