Sennheiser HD 450BT

The HD 450BTs are half the price of Sennheiser’s leading wireless noise-cancellers, so what are the compromises here?

On paper, the full combination of wireless Bluetooth and active noise-cancellation makes the HD 450BT look quite the bargain next to Sennheiser’s $599 flagship Momentum Wireless model (see p50). This design builds on the previous HD 4.50BTNC, the new model upgrading to USB-C charging, extending battery life to an impressive 30hrs, and with a new white option available (pictured) as an alternative to deep-grey/black.

They are solidly if purposefully built in sturdy plastic, with synthetic leather earpads and soft silicone rubber under the headband; they hinge closed compactly to fit into the included small soft cloth bag.

The Bluetooth implementation includes the AAC codec to improve audio from Apple devices; Android devices which are compatible can take advantage of the only slightly lossy aptX options, including aptX Low Latency which reduces the delay of Bluetooth to as little as 40ms, so assisting sync if you’re using the headphones with a TV or for watching, say, videos on a tablet.

The control buttons become fairly intuitive once you’re accustomed to the layout — noise-cancelling can be toggled on and off, and proved effective without being too intrusive, and with only a small effect on the music quality (slightly improved in clarity with noise-cancelling off). You can also summon your smart device’s voice assistant, simultaneously providing a useful ambient mode where you can hear what’s going on outside.

With all this, then, what distinguishes these headphones from the twice-the-price Momentum Wireless? The most obvious initial answer is the comfort; they are remarkably tight to the head around the ears (or were for us), but there’s also the sound, which we thought unusually soft and lifeless for a Sennheiser design, with flabby bass emerging via Bluetooth from iPhone and iPad.

Could we correct the 450BT’s deficiencies? You can use the Smart Control app’s floaty EQ option (pictured), though Sennheiser’s latest approach to EQ is overly graphic and restricts accurate adjustment. Want treble? Then you can’t have bass. Want more bass? Then it rolls off the treble. But our final preference enabled us to to enjoy music somewhere close to the quality we expect from Sennheiser, reducing especially the tendency for the bass to thump a little too prominently. Aphrodite’s Child’s The Beast from ‘666’ has kickdrums panned left and right, and these showed up a tendency to flab at the bottom, as did anything with a strong central bass pedal. After EQing it was thumpy but not so dominant, while the central piano and guitar had additional edge enabling them to cut through.

Via cable — a fallback for a battery crisis, as well as essential for in-flight use — the sound was significantly better, with greater clarity and better tone in a rich spread rather than what had seemed an overloaded thickness of sound via Bluetooth, though overall they still lacked detail in the detail or any sense of airiness. And the fit remained tight, further discouraging long listening.

Overall then the feature count is very good for the price, but the HD 450BT gets a mere pass grade for sound. Which is a rare verdict indeed from us on a Sennheiser headphone.