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Sennheiser isno stranger to studio-grade headphonesand its HD600 series is a testament to that. While the lineup includes only open-back headphones, the latest entry, the Sennheiser HD620S, is the first closed-back headphones to bridge the gap between the two styles. And for the most part, they succeed. They come with a hefty price tag when looking at other closed-back headphones that offer a lot of extra features other than great sound quality, but they are fairly reasonable when it comes to studio monitors.
There are two main headphone styles – closed back andopen back– and both have their advantages and disadvantages. The closed-back headphones, as the name suggests, isolate the listener from the outside world and deliver punchy, often bass-heavy, audio. In comparison, open-back headphones deliver a much more open sound stage but do not isolate the listener, and the sounds often bleed out. That being said, open-back headphones have a more natural sound output.
Sennheiser HD620S
The Sennheiser HD620S are closed-back audiophile headphones that stand as a bridge between open-back and closed-back style headphones. They have a frequency response range of 6 Hz to 30 kHz, which makes them stand out from the crowd. Sennheiser is using 42mm dynamic reference-grade drivers with a 38mm diaphragm for excellent sound output from the 3.5mm jack.
The Unboxing Experience
The box includes:
The Sennheiser HD620S box contains the headphones placed inside a carry pouch with the cable attached and that’s about it. It’s a straightforward unboxing experience, but it would have been better if Sennheiser included a case, especially considering the $350 price tag. The 3.5mm to 6.3mm adapter is already on the cable, and if you wish to use the Sennheiser HD620S with a laptop or mobile device, you just need to screw the adapter off.
There is no in-line mic here, but Sennheiser sells a cable with an in-line mic separately. For the review, Sennheiser sent the cable with the in-line mic along with the headphones.
Design and Build Quality
The Sennheiser HD620S headphones don’t look like any other HD600 series headphones as they are all open-back style, but their shape and design resemble the HD560s (also open-back). They come with artificial leather earpads that have internal venting and soft padding on the headband. The headband and the earcups have stainless-steel reinforcement which bodes well for build quality and longevity but leads to a relatively strong clamping force around the ears. The earcups are large enough to comfortably surround the ears and are deep enough that the inner fabric doesn’t touch the ears either.
The cable has a twist-to-lock mechanism that keeps it firmly in place inside the left earcup and both ends are gold-plated. It doesn’t take long to get used to the twist-and-pull motion, but you probably will not have to use it at all.
The headband adjustment mechanism has defined steps that allow for accurate adjustments, but the overall experience is not as smooth as it could be. It sometimes skips steps when trying to extend or shorten the headband, so you need to be more conscious of the force you use to make any adjustments. The earcups have some swivel as well, adding to the comfort of the headphones, but more on that later. The overall build quality on the Sennheiser HD620S headphones is great, just as expected from a Sennheiser offering.
Specifications and Features
What sets these headphones apart from other closed-back headphones is the wider and more natural sound stage that they offer. This is in part due to the wider frequency response range of 6 Hz to 30 kHz and the reference-grade dynamic 42 mm angled transducers with 38 mm diaphragm. They boast an impedance of 150 Ohms and a Sound Pressure Level (SPL) of 110 dB. This combination translates to a natural and open sonic experience that would be impossible to achieve with standard closed-back headphones.
The Sennheiser HD620S headphones weigh 326 grams, putting them on the heavier side of closed-back headphones, but some of that weight is mitigated by the comfortable headband and earcups. It’s also worth noting that there are no fancy features like active noise cancelation, ambient mode, or touch controls here. The headphones do offer some level of passive noise isolation, which becomes apparent as soon as you put them on your head.
Comfort
Coming to comfort, the Sennheiser HD620S are not the lightest headphones on the market and even though the soft headband and swiveling earcups make them feel comfortable, the weight and clamping force can make them feel somewhat uncomfortable over longer periods of continuous use. That being said, the listener’s head shape and size will ultimately determine the comfort level, but the clamping force is something to keep in mind.
The cable is long enough that it doesn’t get in the way and providessufficient freedom of movement. It doesn’t weigh down the headphones at all. The earcups are soft but not so soft that they compress to the point where your ears start to touch the inside of the earcup. The slight amount of swivel lets them sit more comfortably around the ears.
Sound Quality
Right out of the box, simply plugging the 3.5mm connector into an audio source, you may not feel that much of a difference between the Sennheiser HD620S and other premium closed-back headphones, but the difference becomes more apparent when using an audio interface. We switched between the 3.5mm jack on the MacBook Air, the MacBook Pro (M1 Pro), and the Volt 2USB audio interfaceand found that when supplied with the right quality audio, the Sennheiser HD620S delivered a spacious and accurate sound stage despite their closed-back design, which is what the headphones are aiming for.
The different frequencies are well-separated and well-balanced, but some may feel the bass to be a bit lacking. Of course, the aim is not to deliver punchy, bass-heavy audio like with other closed-back headphones but to deliver a more natural representation of the recorded sound, which these headphones do in spades. Listening to some Hi-Res Tool through the Volt 2 was a sonically invigorating experience. The Sennheiser HD620S works best with music where different instruments are used to record, as they do a great job of representing those frequencies and the vocals without one drowning out the other.
As for sound bleed, there’s quite a lot, especially at higher volumes, so that’s something to keep in mind when using these headphones out in public. You would probably not expect this much sound bleed from a pair of closed-back headphones, but that’s a compromise that audio enthusiasts will be willing to make when considering the openness of the sound.
When it comes to gaming, the Sennheiser HD620S are not advertised as gaming headphones, but they can definitely handle the task. Even though there is no mic included, the separately sold cable with an in-line mic does the job of getting your voice across to your friends. If you wish to use these headphones for gaming, it isideal to invest in an external microphone. Other than the mic, the headphones can accurately represent where the sound is coming from in games, which is essential when playing shooters. Once again, the lack of bass becomes apparent in games, as you don’t get the thump that some other dedicated gaming headphones or other open-back headphones offer.
Overall Impressions
Those looking to upgrade their music listening experience but don’t want to invest in the world of studio monitors will find that the Sennheiser HD620S offers a great sweet spot. They can be easily driven via a standard 3.5mm jack but putting them through an audio interface takes them to the next level. They get extremely loud without distorting the sound and still manage to maintain separation between different instruments. They are not the best for enjoying hip-hop or other bass-heavy music and, despite being closed-back headphones, there’s significant sound bleed, especially at higher volumes.
The build quality is excellent, but the headband adjustment could be better. The clamping force can be a bit high for some users depending on the head size, which may lead to fatigue after a couple of hours of continuous listening. Overall, for $350, the Sennheiser HD620S delivers crisp, open, and natural sound, along with excellent build quality.
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True Open-back audiophile headphones
FAQ
Q: Is Sennheiser HD 620S closed?
Yes, the Sennheiser HD620S are closed-back headphones and the first ones at that, in the HD600 series.
Q: Are all Sennheiser headphones made in Germany?
Sennheiser headphones are manufactured in factories located in the US, Germany, and Ireland.
