Sennheiser HD 650 review – Long Live The King!
It’s hard to overstate the importance of the Sennheiser HD 650. For Sonarworks this headphone was used to translate a neutral sound from speakers to headphones. They’re also used by our engineering team as reference headphones, so they’re really special to us. Let’s find out whether you should get excited about them!

Pros
  • Flattest headphones we've ever measured
  • Great comfort
  • Matched left and right channels
  • Translate well among different users
  • Aren’t too sensitive to positioning changes on one’s ears

Pros list with Sonarworks Reference calibration

  • Sub bass extension greatly improved
  • Deliver pretty much perfectly neutral sound to any listener
Cons
  • Not the most durable headphones out there
  • Weak Sub bass extension
Use cases Best use case:
Great for mixing, mastering and production in studio
Tech specs Type
Open back, Over-ear
Impedance
297 Ohm
Connector
3.5 mm stereo jack
Adapter
Includes 1/4″ to 1/8″ adapter
Weight
260 g (without cable)
Require headphone amp
Yes
Headphone amp

They could definitely lack volume if plugged directly in your phone or a built-in headphone socket on your laptop, especially if you’re using them with Sonarworks calibration and “Safe headroom” enabled. But there’s no need to worry if you’re using an audio interface as any modern unit will drive them loud enough.

Build quality

The manufacturing consistency is great. However, if you’re going to use them frequently, after a few years some parts might need a replacement – lower frequency playback may cause some rumbling and distortion, the headband will become considerably looser, and obviously, ear pads will need replacement as with any headphone used for critical work. Luckily, you can order and replace literally any part of these headphones with ease.

Sound

Sennheiser HD 650 are pretty much the most neutral headphones available on the market. However, their sub-bass response is lacking (frequencies below 100 Hz) and high-mids (around 2-5 kHz) need to be tweaked a bit. Otherwise, they are pretty much good to go straight out of the box.

Channel balance

You would expect from headphone manufacturers perfect matching between left and right drivers. Unfortunately, in the real world, this doesn’t happen too often – pretty much every other pair of headphones have channel inconsistencies even among the well established pro headphone brands. By contrast, Sennheiser is a true expert in offering headphones with matched left and right drivers so that soundstage stays consistent across the spectrum. With some minor exceptions, Sennheiser HD 650 has hardly any inconsistency between the two drivers. On a rare occasion, pairs have slight differences in bass and sub-bass region, but the magnitude is low enough to not cause audible issues with imaging.

Comfort

Based on our experience with various headphone models, we would say that Sennheiser HD 650’s are very comfortable to wear. They are lightweight, fit very well almost any head size and shape and do not cause headaches by creating too much pressure on your ears and temples. Only the largest heads may find the clamping force of HD 650’s on the tight side, but keep in mind that with time the headband will become looser, so the comfort for those with larger heads should only increase over time.  These headphones are a great choice for extensive mixing sessions.

Value

While the asking price of €300/$400 can’t be considered low, these are the flattest sounding headphones out of the box, while being far from the most expensive, so we’re not complaining! If we’re comparing HD 650 to other headphones and forget about calibration for a minute, Sennheiser / Drop HD 58X and 6XX or Sennheiser HD 600 are very close to HD 650 performance straight out of the box, while all are more affordable. However, when used with Sonarworks calibration, Beyerdynamic DT 880 Pro offer near-identical performance of calibrated HD 650 for about half the price.

Observations on how headphones perform after applying Sonarworks Reference calibration Total Harmonic Distortion


These aren’t the cleanest headphones out there when it comes to distortion in the bass region, however, they hold up nicely with anything above 150Hz. While THD figures after calibration in the sub-bass region are high (on average about 10-15%), it’s mostly 2nd harmonic distortion, which means that it won’t be too audible and in most cases will go unnoticed even if you work with bass heavy music. Also, it’s worth keeping in mind that even with their THD figures these headphones will reproduce cleaner bass than many real world playback systems your work will be listened on. Should you absolutely require surgical precision under 100 Hz, get a pair of calibrated closed backs or orthodynamic headphones.

How accurate and consistent is the correction effect among different listeners?

HD 650’s sound nearly the same no matter who is using them. Also, changes in wearing position don’t alter the frequency response much. The consistency of HD 650 is exceptional on all fronts!

How much do they differ pair to pair in terms of frequency response?

Based on our experience, they do not differ a lot from pair to pair. There could be a slight difference in high and high-mid frequency perception, otherwise, they all sound very similar.

Rating

8.4 / 9.1 / 9.6

Sound rating is a weighted average of Frequency Response, Adaptiveness, Harmonic Distortion and Channel Balance scores, with Frequency Response and Adaptiveness having the greatest influence.

7 / 9 / 10

The flatter the frequency response – the higher the score. When evaluating the frequency response score with the Average calibration profile, the pair to pair consistency of the given model is taken into account – if we have measured a considerable frequency response inconsistency among multiple pairs of the given model, the score drops, as the profile loses accuracy. Individual calibration will grant perfectly flat frequency response.

10

Adaptiveness shows how capable these headphones are at delivering the same perceived frequency response to any listener. Headphones with high score will sound nearly identical to everyone.

6

Harmonic distortion – the lower the Total Harmonic Distortion (THD) figure, the higher the score. Headphones with prominent 3rd harmonic distortion above 100 Hz will score lower.

9 / 10

Channel balance – the closer to identical the frequency response of both channels, the higher the score. Individual calibration delivers perfect channel balance.

8

Comfort – shows if headphones can be used for long listening sessions comfortably. Every model is tested by at least a few individuals.

7

Build – evaluates how well the headphones are put together, the materials used and indicates the expected longevity. Easily replaceable (and easily available) parts will boost the score. We don’t do any stress tests and very few models are used for longer than a couple of days, so this is a fairly subjective score.

7

Value – indicates the price-performance ratio of the given headphones and how they stack up against the competition. High score means that you won’t find more neutral sounding alternatives for the price.

Conclusion

These are our all-time favorite headphones. Apart from the weak bass response, there isn’t much correction required to get them absolutely perfect! Once calibrated, we can’t recommend Sennheiser HD 650 enough to anyone looking for production / mixing / mastering studio headphones. Just keep in mind the inherent drawbacks of the open-back design headphones – there’s virtually no sound isolation from the outside world and sound will leak out of the headphones. If these aspects concern you opt for closed-backs, if not – go for it!

You can order individually calibrated Sennheiser HD 650 headphones from our store here.

Final Rating

8.8
With Sonarworks Reference 4
Calibration Enabled
8.2
Without Sonarworks
Calibration

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