The new HD 620S closed back headphones from Sennheiser are open and airy like an open pair … [+]
When Sennheiser announced that it would license its consumer product development to Sonova AG, a Swiss-based hearing aid giant, I was skeptical. At the time of the announcement, I interviewed Andreas and Daniel Sennheiser, joint CEOs of the venerable German headphone company. What I was told at the time greatly eased my fears. However, I knew that the new products developed by Sonova AG would be the acid test of the collaboration.
Several years have passed since the agreement was reached. Since then, Sonova AG has produced several products under the deal, including the Momentum True Wireless 4 headphones and the Sennheiser HD 620S. Any doubts I may have had about the quality of the products and their overall design are completely gone. The collaboration between Sonova AG and Sennheiser has produced new products that are just as good and, in some cases, even better than those created by Sennheiser alone.
The new Sennheiser HD 620S are closed-back headphones featuring custom-tuned 42mm dynamic drivers designed and manufactured at Sennheiser’s Tullamore factory in Ireland. The drivers produced in this factory are some of the best you will ever hear and the investment that has gone into the innovative production line is now paying serious dividends.
The finish and fit of the new Sennheiser HD 620S are exemplary. They are extremely comfortable for him … [+]
The Sennheiser 600 series of headphones has long had a reputation for smooth and lightweight sound. The HD 660S2 open-back headphones I reviewed last year showed just how good Sennheiser is at making traditional dynamic headphones. The HD 660S2 has an open and airy sound that is pure joy; though, being open-back headphones, they aren’t as good at keeping out unwanted sound.
The 42mm drivers in the HD 620S’s ear cups are slightly angled to produce a triangle … [+]
If you want to use a pair of headphones on the go in places where traffic noise and other distractions can disrupt your music, you should choose a closed-back design to keep out unwanted sound and stop the music from leaking while you’re listening. . in public. That’s where the HD 620S headphones come in. These are dynamic headphones with an open and airy sound like the HD 660S2, but with enough isolation to keep the music in and unwanted sounds out.
The new HD 620S has a high damping factor and uses a 150Ω aluminum voice coil, which means the headphones need a high-quality source such as a headphone DAC or a digital audio player. The result is an exciting and punchy sound with plenty of dynamics across the frequency spectrum, which stretches from a roaring 6Hz to a bat-snapping 30kHz. They have the surefootedness and versatility of an open-back headphone, but with all the advantages of a closed-back design.
The chassis used for the new HD620S is like the portrait HD 660S2, albeit with a slightly smaller ear pad. A steel plate seals off the rear volume from the drivers and makes a good insulator while controlling reflected sound waves inside the earcup. The drivers are placed at a slight angle, which promotes free air circulation, mimicking the response of open-back headphones. It’s amazing how well Sennheiser has managed to pull this off.
With the drivers placed at a slight angle, the HD 620S produces triangular imaging for the soundstage, with an effect like listening to a pair of speakers in a great audio setup. The result is an immersive sound that is engaging and suitable for a wide range of music, from live recordings to classic multi-track albums.
The 42mm dynamic drivers used in the Sennheiser HD 620S are made in-house … [+]
The HD 620S are superbly made and finished with a classy, textured plastic that makes them smart and durable. The headband is generously padded with a cutout for the top of the skull and is reinforced with an adjustable metal band to accommodate a wide range of head sizes. The replaceable ear cushions are made from extremely soft leather rather than the velor that Sennheiser often uses. The result is a comfortable fit that covers the entire ear in a circular design. You can wear the HD 620S for long periods and the pads never seem to get sweaty or itchy.
The 1.8mm cable ends with a 3.5mm stereo plug. There is also a 6.3mm screw adapter for listening with hi-fi systems. The cable is detachable and has a 2.5mm plug with a clever locking mechanism that keeps it connected to the left earcup. Later this year, Sennheiser says it will launch a balanced cable with a 4.4mm Pentaconn connector, and I’d like to try this with a digital audio player like the excellent FiiO M23.
The padded headband of the Sennheiser HD 620S has a comfort level for the top of the skull. of … [+]
So far, so good. The HD 620S are a beautifully crafted pair of headphones with an exemplary build quality and fit that’s far from perfect. At 357g including the cable, they’re not the lightest, but somehow, they don’t feel heavy. Now let’s find out what they sound like using the FiiO M23 digital audio player that streams hi-res audio from Tidal.
When Sennheiser says the HD 620S are a closed-back design that sounds like open-back headphones, that’s not an idle boast. I can’t remember ever seeing a pair of closed-back headphones with such an open and airy sound. There’s none of that boxy, claustrophobic quality found in so many traditional closed-back headphones. Even the heat that tends to build up in closed-back headphones seems to dissipate. Making the HD 620S a dream to listen to without overheating your ears or feeling uncomfortable.
The sound is one of the most balanced I’ve ever heard from a pair of dynamic, close-range headphones. Bass is tight and goes down to 6Hz with a controlled, airy punch that vibrates freely, especially when playing acoustic basslines. The sound never falters or becomes unfocused, no matter how energetic the beat gets.
Meanwhile, the middle one is as clean and colorless as can be. Nobody makes dynamic drivers like Sennheiser. The investment in the Tullamore plant has paid real sonic dividends and Sennheiser’s engineers are at the top of their game now.
The triple quality is as silky and smooth as you want it to be. The focus of the soundstage never wavers or misses the mark. Nor does the image become labored or robotic. Balance across the frequency spectrum is as good as it gets with a pair of closed-back headphones. I doubt it can be improved.
The Sennheiser HD 620S is ideal for listening on the move or in situations where there are unwanted … [+]
Verdict: If you like the airy, natural sound of a pair of open-back headphones, but want to listen to music on the go or in places that aren’t as quiet as a dedicated listening room, the Sennheiser HD 620S are a great choice. With all the quiet, unamplified sound of open-back headphones, but all the isolation of a closed-back model, the HD 620S will serve up audiophile-quality sound wherever you are. The fit and feel of these relatively affordable headphones make them the ideal choice for wired listening with a headphone DAC or digital audio player. If you want high-quality sound on the go, the HD 620S offers value and quality at scale.
Price and availability: The HD 620S headphones are available now from selected retailers and on sennheiser-hearing.com priced at $349.99 / £299.99 / €349.90.
Technical characteristics:
- Transformers: Dynamic.
- Diameter: 42 mm with 38 mm diaphragm.
- Frequency response: 6 Hz – 30,000 Hz.
- Sound pressure level: 105dB (1kHz / 1Vrms).
- Impedance: 150Ω.
- Total Harmonic Distortion: -0.05% (1kHz / 90dB SPL).
- Cable: Detachable 1.8 m.
- Output: 3.5mm stereo.
- Weight: 326g (without cable).