2025 is the 80th anniversary of Sennheiser, so it comes as no surprise that they have announced a new headphones to propel them for the next 5 years. The HDB 630 is the first “HDB” series, which I assume is the Bluetooth edition of the audiophile HD-series. It uses the exact design mould of the MOMENTUM 4 while improving the materials. It retails in Singapore for S$749.
The HDB 630 is positioned as a wireless headphone for audiophiles with the following features:
- BTD 700 Bluetooth dongle USB-C adapter included in the package to deliver aptX Adaptive and aptX HD to audio devices that do not support these codecs which offer higher audio quality up to 24-bit 96kHz. If your devices already support these codecs, you do not need to use the BTD 700.
- Audiophile tuning. While the same 42mm SYS38 transducer is used, the HDB 630 has updated the acoustic design with new acoustic mesh and a more neutral tuning on the midrange and treble.
- New advanced Parametric EQ feature in the app allows user to define frequency bands (Q), filters, A/B toggle. The settings can be shared through the app to other users.
- Crossfeed Mode: two presets to blend left and right channel mixes for a more speaker-like presentation.
Sennheiser reuses the “630” number instead of assigning a new one, which may confuse search engines with the discontinued HD 630VB model launched in 2015. It is also not labeled under the “MOMENTUM” series as this new headphones are not positioned for casual listeners, even though the design is identical.
Personally, I would wish that Sennheiser come up with a new design or adopt the HD-series design so as to further distinguish the new headphones, which would otherwise be mistaken as MOMENTUM 4 on the streets unless sharp-eyed enthusiasts look at the upper headband covered in Japanese leatherette. The advantage is that you can share accessories. I applied the MOMENTUM 4 touchpad sticker on the HDB 630 and fits perfectly.
While the leatherette detailing elevates the quality of the HDB 630, I would prefer the fabric wrap design of the MOMENTUM 4 for ease of maintenance.
BTD 700
The dongle included in the HDB 630 is sold separately subject to availability. The HDB 630 does not elaborate on the BTD 700 features, so I had to download the instruction manual separately from the Sennheiser website. The dongle supports aptX, aptX Adaptive Audio, aptX Lossless, LE Audio LC3, SBC. The dongle LED appears on both sides, so you can insert the dongle in any orientation. The dongle supports Auracast broadcast, which means you can listen the same audio with multiple headphones that support LC3 codec.
If the BTD 700 does not auto-connect to the HDB 630, then you need to pair it manually. Press the dongle button for 3 seconds until the LED flashes red and white alternately. Then, press your headphones power button and hold for 5 seconds until the pairing jingle is heard. Once paired, the dongle LED will light up in pink.
Once the dongle pairing is done, you can enable multi-point pairing which allows you to control the headphone settings via the smartphone while listening audio through the USB dongle from another device.
With the BTD 700 included in the bundle, it gives me more incentive to listen music on my laptop as it offers higher quality compared to the built-in laptop Bluetooth chipset.
Audio Quality
A high-recommended setting change once you pair the HDB 630 to the smartphone, go to the smartphone app, headphone settings -> audio mode priority, and enable “Hi-Res”. It will dramatically improve the sound with less compression, wider dynamic expression.
The first impression I get when I listen to the HDB 630 is that they sound more neutral than the MOMENTUM 4, while I get more musical clarity and bass compared to the HD 650. The sound is less coloured yet it continues to produce detailed instrumental texture and musical precision that excites discerning listeners. I have to admit that MOMENTUM 4 sounds more engaging but it is a less accurate-sounding headphones.
The HDB 630 has a much better sounding midrange, warm yet does not muddy up the mix. Even recordings with strong harmonics is managed cleanly coming from brass instruments. One listening experience when auditioning Hiromi’s “The Player” track is that I can hear piano’s left-hand passages better, hear the bass guitar lines more distinctly, even when they all perform simultaneously in the recording. It makes the HDB 630 a little more special than other headphones.
While the bass is not as intense as MOMENTUM 4, the HDB 630 still offer satisfying punch and depth while, once again, not masking the mix. It does not make the music sound heavy, yet the musical depth remains forthcoming to be enjoyed. Treble is not excessively bright and fatiguing, but offers clinical clarity like the hi-hats without lingering decay. delivering the outcome of sonic precision without the harshness. Overall, treble still sounds sizzling but with a more weighted midrange to keep the sound balanced instead of skewing too much on both spectrums.
I spent a bit of time comparing the various connection modes and here are my insighs:
- Bluetooth connection via smartphone (Honor Magic7 Pro) through aptX Adaptive codec: this is the baseline sound as described above. Slight dynamic compression is detected (compared to the other modes) due to volume adjustment. Volume step is not fine enough so I could not get the right volume level for better listening comfort.
- Bluetooth connection via BTD 700 through aptX Adaptive codec: somehow the sound quality is slightly more resolving, less compressed than the above. It goes to show that it might be more beneficial to use BTD 700 even though your smartphone has built-in Bluetooth.
- USB connection on Windows laptop using Foobar2000 audio player: This mode represents the direct sound driven by the headphones DAC. I detect that the midrange sounds more warm, more prominent. Dynamics is wider, more analogue sounding. Note: in this connection, the headphones can still pair to another Bluetooth device.
- 3.5mm connection on Creative Sound Blaster X5 headphones amp connected to WIndows laptop using Foobar2000: This mode relies partly on the Creative amp’s DAC to deliver the audio signal, hence it does not represent the true sound signature of the HDB 630. In this setup, I find there is more prominent bass depth, the midrange is even smoother than the USB connection. Note: when the 3.5mm cable is connected, the Bluetooth radio is turned off. Tip: I can use the same cable as the HD 550/620S as the headphone connector is the same 2.5mm size.
Even when listening in wired mode, enabling ANC offers an even more immersive listening experience, as if I am sitting inside the soundproof room. I can easily hear even more recorded details that I would otherwise miss on other headphones. I am astounded that I could hear some breathing sound from the artist.
HDB 630 vs. Headphones
Sennheiser has provided their own frequency curve charts to compare the HDB 630 with the HD 650, HD 620S, and MOMENTUM 4.
I do not have the HD 650 with me (sold many years ago), but the graph shows the tuning difference at both ends of the spectrum. I also do not have the MOMENTUM 4, but having only recently reviewed, I can still recall the sound, and the below graph matches my impression, where the bass and treble are more elevated on M4.
I’m glad that Sennheiser has the comparison graph for the HD 620S. I’m sure many consumers will be curious how they both compare, as the HD 620S is also a closed-back headphones. I have both headphones, so I did a listening comparison. True to the graph below, the HDB 630 delivers more articulated and prominent bass response. What’s interesting is the treble, where the HD 620S sounded less precise, more bloomy. Through this comparison, the HDB 630 outshines with its acoustic design.
I also compared with the HD 550, and the result is mixed. Since the HD 550 is open-back, the characteristics are different and so any comparison is not that relevant. But still I will describe how they sound to me.
The HD 550 has a more open sound, more natural staging, less intimate, less bass impact, midrange is less warm. But it wins on comfort. The HDB 630 is obviously able to deliver much more precise sound because the closed-back plus ANC eliminates all environmental distractions, so you hear every fine recording artifact picked up by the studio mic. If you find the HD 550 lacking in sound isolation, get HDB 630.
Moving on to comparing other non-Sennheiser brands. For the Technics A800, the tuning puts weight on the mid bass delivering more boom to the sound, the treble is clear but recessed, midrange is overpowered by the bass and not as prominent. Definitely not ideal for consumers wanting accurate sound, but it has been my companion for years during public commute because under these noisy conditions, I need musical excitement more than accuracy, and the A800 gives me a good bass to accompany my travels. But it has recently been dethroned by the JBL Tour One M3,
The JBL Tour One M3 has a more roomy sound staging, more distinct instrumental separation. Bass is more lean, less weight, midrange does not sound as compact and warm, treble cymbals and hi-hat are not as forward, whereas the HDB 630 sounds more articulated at the treble and midrange. Other than audio, the JBL headphones is generally a better headphones for its foldable design, more powerful ANC, more functions on the smartphone app, and is also less expensive.
Verdict
When one uses the term “neutral sound”, it could give a misconception that the headphones sound dull and flat. This is far from the truth with the HDB 630. I am impressed at how the headphone is tuned to be neutral and yet offers enjoyable bass impact, forthcoming midrange, sparkling treble, without applying a V-shaped tuning. On top of that, musical clarity is consistent across the frequency. Sennheiser tuned the drivers so that the bass rumbles without too boomy, the midrange sings without too bloaty, and the treble sparkles without too harsh. The sonic character is clean without distracting aftertones, decay or reflection.
The HDB 630 is one headphones that reveals its true quality only when doing listening comparison. It is through comparison that I get to hear how the HDB 630 can sound more pleasing, more detailed, more balanced, than other headphones. With other headphones, you may get first positive impression of “great bass” or “clear treble”, but you will soon realise that such tuning comes with compromises, which many accepts due to the soundwave limitation – you cannot have strong bass, midrange and treble altogether.
Then again, with a retail price of S$749, the HDB 630 is targeting discerning consumers who understand sound balance and want an uncompromising wireless headphones. The great thing is that while the wireless mode is already impressive, the wired mode reaps even greater listening reward, making it possibly a serious contender for the wired market.
The HDB 630 has won my heart and my ears as the best-sounding neutral-tuned consumer headphones.
