Review: Sennheiser HD 4.50 BTNC

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With the continued push for wireless connectivity in today’s consumer tech, wireless headphones are becoming more the norm. While Sennheiser has offered premium wireless headphones for some time now, they recently released two slightly more budget-friendly options: the HD 4.40 BT (reviewed here) and the HD 4.50 BTNC noise cancelling headphones.

$200 is not much money relative to other wireless, noise-cancelling options currently in the market, so there are two questions to answer: (1) are the HD 4.50 headphones good, in absolute terms, and (2) are the HD 4.50 worth the $50+ premium over their bluetooth-only sibling?

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Styling & Features

The HD 4.40 and HD 4.50 headphones are both very simple, attractive headphones. While still being full-size headphones, they don’t look that large and are generally pretty inconspicuous. Like the HD 4.40, the HD 4.50 have an impressive build quality and attention to detail, though I actually prefer the 4.40’s black-and-titanium color scheme over the 4.50’s black-and-bright-silver look, but that’s simply personal preference. 

The left ear cup houses an NFC panel, while the right cup is home to several multi-purpose buttons, a microUSB port (for charging only) and a 3.5mm jack for passive use. Noise cancelling can be used during 3.5mm connection. In addition to noise cancelling, the feature set includes bluetooth 4.0, AptX codec (with a compatible phone), NFC, and so-so phone call quality.

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As I explained in my HD 4.40 review, I have a real problem with Sennheiser’s persistence in shrinking their full-size headphones. These are considered “circumaural” headphones, which means they are supposed to sit on your head, with the ear pads completely surrounding your ears. In reality, the ear pads are just too small. I believe my ears are pretty average-sized, but these “scoop” my ears inward to fit inside, leaving my ears bent and hot inside the closed-back headphones. After about an hour, I need to give my poor ears a break. 

 The HD 4.40 BT's ear pads are nearly twice as thick, which has pros and cons. 

The HD 4.40 BT's ear pads are nearly twice as thick, which has pros and cons. 

The ear pads are pretty different between the HD 4.40 and HD 4.50. The HD 4.50 ear pads are much shallower, appear to be a higher-quality construction, have slightly firmer foam innards, and seem to generally be slightly more comfortable (though, still not comfortable). One apparent consequence is a harder time getting a good seal. A bad seal not only impacts comfort and passive noise isolation, but also degrades bass response. 

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Noise Cancelling

Active noise cancelling has never impressed me much, on any headphone, and the 4.50 is no exception. While it can reduce the low-pitch hum of an air conditioner, a plane, or road noise, noise cancelling will do very little to higher-pitch noises. Sennheiser’s user guide even says,

“Tiny microphones pick up low-frequency ambient noise near the ear. The NoiseGard electronics use this noise to generate a sound wave which is the exact opposite, the effect being that the polarity reversed signal cancels most of the outside noise."

They are intentional to say that it (1) only works for low-pitch noises and (2) only reduces, rather than eliminates environmental noise. Don’t expect them to do much for office chatter, a crying baby, or a loud coffee shop; you will be disappointed. Higher-frequency noises are only reduced through passive isolation from their closed-back design, and the HD 4.40 is just as successful on that front.

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Sound Quality

There’s another issue with the noise cancelling: it really impacts the sound signature. While it retains some impact around 100 Hz (think the "slam" of a kick drum), upper-bass nearly disappears, losing body and warmth, and sub-bass rapidly tapers to nothing. More distracting than that, the upper-mid frequency response peak shifts downward toward 2 kHz and there’s a hole in the 3-5 kHz range. These two treble issues give a very forward, nasally sound while also lacking clarity and definition. It’s just plain unnatural-sounding and I find it generally unpleasant. 

If the noise cancelling situation wasn’t bad enough, I’ve consistently noticed one final issue: the slightest bump or thud, from touching the headphones to walking too hard, causes a brief moment of distortion. I’m guessing it’s due to interference with the noise cancelling’s microphones, since it doesn’t happen with noise cancelling turned off, but I can’t be sure of the cause. 

The sound quality really improves with the noise cancelling turned off. They become a very pleasant and warm-sounding headphone. Bass actually becomes too exaggerated to be considered neutral, but it’s a tasteful amount and I think most people would enjoy it. The overall frequency response really smooths out and the treble peak shifts upward toward to a more natural 3 kHz, though I consider the highs still pretty rolled off and “polite.” 

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Question 1: Are the HD 4.50 BTNC headphones good, in absolute terms? 

As bluetooth headphones (and the noise cancelling turned off), they’re really not bad. Strong construction, a good value, handsome looks, and I haven’t had a single issue with bluetooth connection. The comfort is OK in short listening sessions and with the noise cancelling turned off, the sound quality is really pretty great for a $200 pair of headphones. 

As noise cancelling headphones, they struggle. The noise cancelling itself does very little to eliminate outside noise and basically destroys the sound signature. It’s worth biting the bullet and stepping up to the $300-400 range. 

Question 2: Are the HD 4.50 worth the $50+ premium over the HD 4.40?

Easy: no. They’re essentially the same headphones when the 4.50’s noise cancelling is turned off, and when it’s turned on, the 4.40 sound miles better. So you’d basically be paying $50-60 more for an option that reduces the noise of your air conditioner and makes your music sound very mediocre. Not a great value proposition. 

If noise cancelling is really important to you, step up to the Bose QC35 II or Sony WH-1000XM2. If not, save your hard-earned money and buy the HD 4.40 instead.