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Welcome to the Sennheiser HD 650s. Below are the left, middle,

and right of the headphones.


The HD 650s are open-backed headphones, which is obvious if you

look at the outside of the ear cups. You can see the headphones'

innards clearly through the external grating.



The underside of the cups is where the cord attaches.


The underside of the band has padding with a divot at the top to

allow the band to bend without scrunching up the pads.



The headphones come with a Y-style cable that's over 9 feet long.


Here's a close-up of the plugs that affix

the cable to the ear cups.


As always, we conclude our tour by taking candid photos of HATS, our

head-and-torso-simulating robot pal, wearing the headphones it's helped

us test. Use this picture to get a very, very, very vague impression of

what the headphones will look like on your own head. We've gone ahead

and assumed you won't always remember to make the band symmetrically

extended, leading to a slight off-kilter look.




In The Box

In the box you'll find a storage case and an 1/8-inch adapter.




The HD 650s seem to be a pretty durable set of headphones overall,

with very specific strengths and weaknesses. On the plus side, the cord

is thick (a plus on at-home headphones, but makes them less portable)

and also removeable. If the cord gets damaged, just swap it out for a

new one.

On the negative end, the HD 650s have an open-backed design. While

open backs do some nice things for sound quality, it lets dust get into

the guts of the headphone very easily. Further, the grating isn't

particularly sturdy, and will probably dent if it fell off your desk.

Unless your desk is several hundred feet above ground, the dent will

likely just be an aesthetic issue.

These negative features are very minor in relation to the overall

construction of the headphones, however. While some dust can flow

through the grates, there's a felt guard to protect the important bits.

In general, the HD 650s are a sturdy set of headphones.




We like the looks of the Sennheiser HD 650s, but their unique look

certainly won't be for everyone. The large oval grating on the outside

of the ear cups is functional, of course, but also creates an

interesting look. The headphones are over-ears, which might look a bit

large on your head if you're not used to them. The greyscale paint job

doesn't create much of an aesthetic draw. While this might make them a

bit boring to some, it also makes them work-appropriate (if you are

planning on using these at work, we have to warn you: they leak like

crazy, so you'll have to keep your volume down if you don't want to be

the office boom box).

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About our testing:**

For more information on our tests, read this



Response**     (*4.42**)*

What we found:

The HD 650s had an average frequency response. As you can see, the

headphones have an average response in the bass end, but gradually fall

off towards the high-end. The response becomes slightly erratic as

well, leading it to dip slightly below the bottom limit a few times by

varying amounts.

While the HD 650s didn't have a perfect response, they still did pretty

well. They never went drastically far outside our set limits and there

weren't any sharp volume changes across small frequency bands.






How the Sennheiser HD 650 compares:

What is frequency response?

The term 'frequency response' describes the amount of emphasis the

headphones put on each frequency. Some headphones try not to alter

anything (reference headphones), but some choose to emphasis certain

frequency ranges, such as boosting bass (dynamic headphones).

How the test works:

For this magical test, step one is putting the headphones on HATS. Once

step one is completed, we play a frequency sweep through the headphones

(step 2). HATS listens to the playback (step 3) then reports back to

SoundCheck (step 4). SoundCheck compares HATS's data to the original

sound (step 5), then spits out a graph that depicts what the headphones

are doing to the playback. We then write up a review (step 6) and post

it on the internet (step 7). If you want to learn more click this

(step 8 [optional]).



What we found:

The less distortion a set of headphones has, the less we can say about

it. The HD 650s didn't have a noticeable amount of distortion at any

point throughout the frequency gamut we tested. Audiophiles should be

quite happy with these headphones.









How the Sennheiser HD 650 compares:

**What is distortion?

*Bad, for starters, but only if you listen to certain kinds

of music. Distortion refers to any garbage the headphones add to your

music. This could be noise, or simply changing the shape of the

incoming soundwaves. If you listen to acoustic music, you'll notice

distortion much more easily than if you listen to rock or punk.

How the test works:

Our distortion test plays a series of frequencies through the

headphones, allowing us to compare the original to the recorded sound,

thus figuring out what the headphones are doing. If you want to read a

longer explanation, this

will make all your wildest dreams come true.




What we found:

The HD 650s had good tracking overall. This means there wasn't any

frequency at which the left ear cup was playing noticeably louder than

the right, and vice versa.










How the Sennheiser HD 650 compares:

**What is tracking?

*Tracking describes the relative volume output of the left

and right channels (in this case, the left and right ear cups). If a

sound is set to play through both ear cups at the same decibel level,

both ear cups should be outputting the same decibel level as well. If

the left channel consistently plays bass louder, or if the right

channel tends to screech high-end frequencies at you, then your

headphones have bad tracking.

How the test works:

This test is an easy one. We just play a frequency sweep through the

headphones and have HATS listen. Each frequency is set to play back

through each channel at the same volume. We note the spots at which one

channel is louder, and that gives us the above graph. When the line

drifts above the X-axis, the right channel is louder. When the line

dips below the X-axis, the left channel is louder. For more info, you

can click here.



Usable Volume**     (6.51)

What we found:

The HD 650s were capable of outputting 105.33dB without accruing

significant distortion. Given that these headphones have open backs,

this is actually pretty impressive and should allow you to annoy

everyone in the vicinity with your music.

We award maximum points for 120dB, which is the loudest you'd want

your playback unless you're determined to deafen yourself. Since the HD

650s are open-backed headphones meant to be used in a private listening

environment, 105dB should be plenty loud.

**What is maximum usable volume?

*Most headphones are capable of a very high volume output,

but sometines that output sounds like garbage. This is because an

increase in volume can often increase distortion. The level of

distortion we look for is 3%, which is when your music will start

sounding ugly.

How the test works:

This test is a series of our distortion tests run at various decibel

levels. We keep bumping up the volume until we hit 3% distortion or

120dB (for which we award maximum points: 10). The reason we don't keep

awarding points past 120dB is because we love you and don't want you to

hurt your precious little ears. If you would like to read more about

this or our other tests: link.



What we found:

We have found, through scientifically rigorous testing, that

open-backed headphones don't isolate well. This may be shocking news to

some, but we assure you it's correct.

Since the HD 650s don't have any physical barrier blocking out external

noise, and they don't have any active cancellation wizardry going on,

they have very poor isolation.






How the Sennheiser HD 650 compares:

**What is isolation?

*Isolation is what stops all the noise of this world we

live in from interrupting your music. Headphones with great isolation

will totally block out ambient noise, while headphones with poor

isolation will allow the car horns and jackhammering to sing along with

your music. There are two types of isolation: passive isolation and

active cancellation. Active cancellation uses a microphone in the

headphones to listen to surrounding noise, then plays back its inverse.

The noise crashes into its inverse, and both cease to be. The downside

is this process requires batteries and isn't perfect: it often creates

as much noise as it blocks out, or adds distortion to your music.

Passive isolation is the brute force approach, and blocks out noise by

simple virtue of a solidity. Stick any solid object into or onto your

ears and you've achieved passive isolation. Some soundwaves will not

make it through the barrier at an audible level.

How the test works:

For our isolation test, we play a bunch of noise at HATS, who is

wearing the test headphones. HATS records the levels of noise it can

hear, which lets us know exactly what's being blocked out. If you would

like to know more about this test, feel free to peruse this




What we found:

Again, since these are open-backed headphones, there isn't much of a

barrier between your soundstage and the world around you. The HD 650s

leak like crazy, thusly fulfilling the purpose of their design.

What is leakage?

In the world of headphones, leakage describes the degree to which your

playback will be audible to those around you. If a set of headphones

has open backs, playback will seem about as loud to those around you as

it does to you. While this is a not-so-subtle way to impress those

around you with your impeccible taste in music, it's also inappropriate

at most times. If you're in the office, for example, you probably don't

want headphones with high leakage.

How the test works:

To test leakage, we put the headphones on HATS and play some noise back

through them. There's a microphone set up a small distance away that

records any and all noise that's audible. From there we toss that data

into a very complicated formula and (huzzah!) we have our score.


**Short-Term Use**    


The Sennheiser HD 650s might not have the softest velour or

sheepskin padding, but the headphones themselves are pretty comfortable

to wear. The headphones are very light and don't put a lot of pressure

on the head, either on the top or on the sides. After an hour we had no

real complaints.

**Extended Use**    


We really didn't have any complaints after a marathon listening

session of 6 hours. They didn't really become less comfortable over

time, although the padding grew to be slightly itchy at times. Overall,

the HD 650s provided a comfortable wear experience.

Of course, this score and the one above are entirely subjective. Try on

the headphones yourselves for at least a few hours before you make a

final decision about keeping them. As anyone who's worn an

uncomfortable set of headphones can assure you, this is very, very




There really isn't a lot of customization available for the HD 650s.

You can tilt and swivel the ear cups slightly and the band can extend.

There aren't any additional add-ons or optional accessories included in

the box.




Connectivity**     (12.22*)*

 The HD 650s cable is 9 feet, 9 inches, which is a great length

for a set of at-home headphones. This is long enough to stretch to an

audio set-up that's across the room from your favorite easy chair.


The HD 650s have a 1/4-inch plug but come with an 1/8-inch adaptor.



These aren't portable headphones in any sense. First of all, they're

large; if they're not no your head, you'll need a separate bag or

container to carry them since there's no way they'd fit in your pocket.

Also, the thick, long cord is simply unwieldy, taking up a significant

amount of pocket space.

The headphones do come with a case, but it doesn't help you port

them around much. There's no latch to it, so it's really better used as

a storage device.




 There's not an awful lot you can do for headphone maintenance.

You can take off the padding, but that doesn't really get you to

anything worth repairing. You can't remove the grating, so if the back

of the headphones get dusty you'll have to rely on compressed air. The

one positive maintenance feature is the removeable cord. If the cord

should succumb to wear and tear in some way, you can cheaply replace it

with a new one.

**Other Features**    


Battery Dependency

The HD 650s don't require batteries, so they get some points here. This

is because batteries are annoying. They require you to maintain an

additional power source, either by recharging or replacing the

batteries. If your iPod still has juice, you should be able to listen

to music with them.



The HD 650s have better aesthetics and durability. The HD 555s are

very plasticky and don't inspire a lot of confidence in their

ruggedness. The HD 650s have a much more solid construction.

**Sound Quality**


HEY, READ THIS: **We have to start this section with a caveat. See,

the HD 555 was one of the first headphones we ever tested (oh,

nostalgia), so the graph extends all the way down to 20Hz. We stopped

showing that part of the graph because our testing rig isn't 100%

accurate for that range. Just disregard the bit below 100Hz and you'll

be fine.

The HD 650s gain a tiny advantage on frequency

response. The HD 555 had a slightly more erratic high end. The

differences between the two are minor.

The HD 555s' graph is a bit misleading because,

like the graph above, it includes data from the 20-100Hz range.

Disregarding that chunk, you can see that the HD 555s still have

slightly more low-end distortion than the HD 650s, but slightly less

distortion overall. Basically, neither set of headphones has much


The HD 650 gets a solid advantage here with an

even tracking. The HD 555 has some issues with the high end.


Neither set of headphones is a good choice if you're looking for



Both sets of headphones have very similar fit and padding type.

They're about the same in terms of comfort.




While the HD 650s are a better set of headphones, they aren't better

by all that much. Most of their advantages come in the form of

subjective qualities, like clarity and a larger, more open soundstage.

In terms of our testing, however, they're really similar. We recommend

trying them on back-to-back and seeing if the HD 650s manage to strike

you as worth the extra few hundred dollars.



The ATH-ESW9s are a high-class set of headphones. They have wooden

backs and lambskin padding. They look quite rich.

The ATH-ESW9s also feature a slightly more sturdy construction, mainly

due to their closed backs.

**Sound Quality**

The ATH-ESW9s have some issues with their high

end. After 1kHz, the ATH-ESW9's response starts dropping and falls

below our bottom limit, then becomes erratic.

In terms of distortion, both headphones are equally amazing.

The HD 650s have better overall tracking, remaining much flatter up

until the high end and remains less erratic as it approaches the 10kHz



The ATH-ESW9 can isolate much better than the HD 650, but we

wouldn't say either have particularly good isolation.


The HD 650s are more comfortable overall. We thought the ATH-ESW9s

were too tight and got slightly worse over time. The ATH-ESW9s had far

more comfortable padding, however, so be sure to try on both sets of

headphones: if you don't run into the fit issues we did, the ATH-ESW9s

would easily be more comfortable.


Both the HD 650s and ATH-ESW9s have different strengths and

weaknesses. The ATH-ESW9s don't have the same calibur audio quality

that the HD 650s do, but they look significantly nicer. If you're not

much of an audiophile and you want a good sound and better looks, the

ATH-ESW9s are a good option.



We think the DT 990s are sharp-looking headphones. The splash of

color doesn't make them a goofy set of DJ headphones that aren't

appropriate, it just makes them delightful. They're also a more

traditional design as opposed to the beehive-like grate on the HD 650s.

The DT 990s are also slightly more durable, sacrificing a true open

back for a less permeable design. They also implement metal in leiu of


One additional aspect to keep in mind is Beyerdynamic's MANUFAKTUR

feature, where you can order a pair of DT 990s online and choose your

own color combination.

**Sound Quality**

The DT 990s did a better job staying within our

frequency response limits, but they have a significant decibel hike

around the 7kHz mark.

There's virtually no distortion on either side,

although the HD 650 features slightly less.

The HD 650s have better tracking. Like most

headphones, the DT 990s have a slight blip towards their high-end.


Neither set of headphones are good isolators. The DT 990s do a

slightly better job, but it's nothing to brag about.


While both headphones are comfortable initially, the DT 990s got

increasingly uncomfortable over time. The band pressed hard against the

top of our testers' heads after a few hours, requiring them to shift

the band to continue use.


The DT 990s feature a slightly better set of test results and an

uncomfortable fit. This comparison is so close that it's really up to

the user to decide which one is better. Be sure to wear them for a few

hours to check for any fit issues. If you find the DT 990s are

comfortable, they slightly superior sound and lower price point will

probably be the better bet.


The DT 990s say, 'I am a pair of high-end headphones, but not stuck

up about it.' The Grado SR60s say, 'Haha, hey guys, remember the '80s?

I'm so ironically attractive it laps regular irony and puts me into

double, if not triple irony.'

Aesthetics aside, the DT 990s are far, far more durable, featuring much

more metal than plastic.

**Sound Quality**

The Grado SR60s have a slightly better frequency response, although

it does feature a pronounced dip towards its high end.

The Grado SR60s don't have the best distortion result, showing some

low-end and high-end spikes. The HD 650s features smooth sailing along

the zero line.

The HD 650s have a smoother tracking result, which was again achieved

simply by not screwing up the high-end.


While the HD 650s are better isolators, neither set of headphones

should be your first choice in this category.


The Grado SR60s have bad padding. Not only do they dilute the audio

quality by creating a terrible seal with their user's ears, but they

also get hot and scratchy. The headphones themselves, however, fit


We thought the HD 650s we a better wear experience overall.


The SR60s aren't a bad set of headphones for their price. If you

like their looks and can get some replacement padding, then they're a

good pick-up. The DT 990s, however, are stellar right out of the box,

and they're certainly more un-ironically attractive.

Meet the tester

Mark Brezinski

Mark Brezinski

Senior Writer


Mark Brezinski is a senior writer with seven years of experience reviewing consumer tech and home appliances.

See all of Mark Brezinski's reviews

Checking our work.

We use standardized and scientific testing methods to scrutinize every product and provide you with objectively accurate results. If you’ve found different results in your own research, email us and we’ll compare notes. If it looks substantial, we’ll gladly re-test a product to try and reproduce these results. After all, peer reviews are a critical part of any scientific process.

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