Sennheiser inadvertently revealed the existence of a new model “HD 550” when they printed it on the HD 505 safety guide. I then searched online but found very little info, save for someone selling online from France. A few weeks later, Sonova/Sennheiser informed me that indeed they are releasing a new HD 550 headphones and sent over a pre-launch unit for me to review.
Available in Singapore from 14 April (price to be revealed), the HD 550 is physically identical to the HD 505 except it uses silver colour accents instead of copper. The HD 505 metal mesh earcup covers have an additional coat of black finishing and the copper logo has a concentric ring pattern, making the HD 505 appearing more outstanding and premium-styled.
What are the technical differences between the HD 550 and HD505?
| HD 550 | HD 505 | |
| Transducer Size | 38mm | 38mm |
| Frequency Response | 6 to 39,500 Hz | 12 to 38,500 Hz |
| Sound Pressure Level (SPL) | 106.7 dB (1 kHz / 1 Vrms) | 107.9 dB (1 kHz / 1 Vrms) |
| Magnetic Field Strength | 21 mT | 21.2 mT |
| Impedance | 150 ohms | 120 ohms |
| Total Harmonic Distortion (THD) | <0.2% (1 kHz / 90 dB SPL) | <0.2% (1 kHz / 90 dB SPL) |
As for the naming convention, Sennheiser revealed on Head-Fi that going forward, the numbering will be more structured.
So apparently, the HD 505 is an Amazon-exclusive release hence the special plain-brown package, while the HD 550 is available from all retailers.
From the above images, the baffle appears to use different dust filter design that may contribute to the slight difference in the audio balance. The HD 550 exposes the drivers a little more than the HD 505, which I believe contributes to the sound signature.
To put it in simple terms, the HD 550 has slightly more bass while the HD 505 has slightly more emphasis on the upper frequencies. For me, it’s not that easy to tell the difference unless I make direct A-B comparison. Even when you look at the graphs above, they may seem similar. Other than the frequency response, both headphones offer identical sound staging, stereo imaging, and comfort.
But as I listen and compare my reference tracks with these two headphones, it becomes more obvious that the HD 550 offers a little more bass resonance that makes the music more filling at the lower frequencies. At the upper midrange, where the vocals reside, the HD 505 offers more clarity while the instrumental body takes a step back. So the vocals have more warmth and body on the HD 550 while the HD 505 sounds relatively clearer and more bite.
The decision between the two is quite straightforward: choose the HD 550 if you like your music to have more bass and more warm tones exuding from the performers, and go for HD 505 if you prefer a little more sparkle.
Just like the HD 505, the HD 550 is very comfortable to wear, the sound staging is close which brings instrumentation details towards the listener. The separation is not exceptionally obvious but because it is open-back, it does not sound cluttered and so the details are still out there.
The overall musical presentation across the frequency range is well-balanced, where the sounds are cohesive instead of too detached nor too clinical. There is more bass to command presence but not too much to overpower, the midrange is warm but not too sluggish nor bloated, the treble is clear and snappy without excessive harshness.
Verdict
A lot of audiophiles will continue to regard the HD 600 or HD 650 as the reference headphones, but for me, the HD 550 is my new reference, where this is the headphones that I would consider the “new neutral”. It truly produces the music tonality in its most uncoloured state.
For sure, there are better-sounding headphones out there, those that either offer extreme bass performance or deliver better instrumental clarity and separation. The HD 550 may not be the best-sounding headphones, but it produces accurately balanced sound that I can trust.
