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Sennheiser HD660s - divisive headphones

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#1
I wanted headphones for critical listening in a quiet environment where sound leakage doesn't matter and having spent a few days on and off researching I have just ordered a pair of HD660s. At the outset I had dismissed these based on their lukewarm response from reviewers and self-proclaimed audiophiles but the more I read the more I thought the HD660s was the better bet. Auditioning wasn't possible due to Covid.
These headphones seem to divide opinion. My simplified analysis of opinions I've read:
Criticisms: a) They have weak and loose sub bass. If you try to correct this with EQ they distort to unacceptable levels (such and such headphone is better in this area, e.g. DT 1990 Pro, Sundara or whatever); b) They're no more resolving than HD600/HD650/HD6XX, so they're overpriced.
Pros: a) These correct a couple of frequency response issues with the previous 6 series models. b) resolving characteristics are slightly improved over 600/650.
I use EQ on headphones, tuning to the 2018 Harman Target and then reducing bass by -3 dB. I know not everyone likes the Harman sound or wants to EQ at all. My preference is to hear something close to flat speakers in a well treated room. That's what the engineers and producer heard and to my ears it always sounds good for well produced music. Coloured sound signatures generally sound bad to me, particularly excessive treble. Therefore, I'm more interested in potential performance after EQ than with stock frequency response.
 

threni

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#2
I wanted headphones for critical listening in a quiet environment where sound leakage doesn't matter and having spent a few days on and off researching I have just ordered a pair of HD660s. At the outset I had dismissed these based on their lukewarm response from reviewers and self-proclaimed audiophiles but the more I read the more I thought the HD660s was the better bet. Auditioning wasn't possible due to Covid.
These headphones seem to divide opinion. My simplified analysis of opinions I've read:
Criticisms: a) They have weak and loose sub bass. If you try to correct this with EQ they distort to unacceptable levels (such and such headphone is better in this area, e.g. DT 1990 Pro, Sundara or whatever); b) They're no more resolving than HD600/HD650/HD6XX, so they're overpriced.
Pros: a) These correct a couple of frequency response issues with the previous 6 series models. b) resolving characteristics are slightly improved over 600/650.
I use EQ on headphones, tuning to the 2018 Harman Target and then reducing bass by -3 dB. I know not everyone likes the Harman sound or wants to EQ at all. My preference is to hear something close to flat speakers in a well treated room. That's what the engineers and producer heard and to my ears it always sounds good for well produced music. Coloured sound signatures generally sound bad to me, particularly excessive treble. Therefore, I'm more interested in potential performance after EQ than with stock frequency response.
I think they're great. I remember being amused around a year or so ago just before I bought them watching some old guy talking about them in a youtube video, almost crying. I don't have the patience or inclination to add back a gui into my headless Pi, getting pulseeffects or whatever installed and configured with the headphones. I just plugged in a Loki Mini, boosted the bass a tad, boosted the treble too, and job done. I have no idea how anyone's getting a lack of bass, or distortion from too much bass, with these headphones. I do feel a little extra treble could be justified. Seasoning is always a personal choice though, isn't it.
 

3125b

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#3
From the reviews I've seen they seem to have a little less even higs, a little less bass extension and a bit more midbass-bloat than the HD 600. And of course they share the same mediocre look and feel of the older entires, while being even more expensive.
On the plus side, the drivers might be a little more capable apart from the (subjectively) worse tuning and they come with a balanced cable.

I don't know, if you get a good deal on them why not, but for the usual retail price, in Europe the HD 600 still seem like the best model of the series, at least to my taste. The HD 6XX are a great deal in the US.

EQ wise, looking at Oratorys work, the HD 600 scores the closest to Harman before (92/100) and after (107/100) EQ. If at all possible, testing the headphones yourself is the best thing to do of course.
It's a good idea to not boost the bass up to Harman level, because without anything to build pressure against, in open-back headphones the bass becomes boomy rather than authoritative in my opinion.
 
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solderdude

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#4


HD660S has a bit less clarity compared to the HD650 and HD600.
As most folks 'complained' about the over the top clarity of the HD600 (presence in the 3kHz area) this was 'solved' in the HD660S.

So a HD650 with less clarity.

They can be EQ'ed but not with impressively loud subbass EQ'ed in.
The small peak around 5kHz should be EQ'ed and one can EQ 30Hz about +5dB, 60Hz +1dB
 

Jose Hidalgo

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#5
Hi LaurenDean,

I had to face the same choice about 6 months ago. I ended up buying a HD600 and I'm glad I did. I think most people should, provided they have access to EQ.

The HD660S is clearly overpriced. The HD600 is much cheaper, and like 3125b wisely said, it can be EQed closer to the Harman curve (as shown by Oratory's preference score), so ultimately the EQed result will be 'better' if I dare put it that way.

About the Pros you mentioned, a) simply doesn't matter anymore if you EQ them. Just check the HD600 EQed frequency response : it's really hard to get any closer than that to the actual Harman curve. And b), no, I don't think the HD660S is more resolving than the previous models (I would need scientific evidence to back up that claim, not subjective impressions). So within the Sennheiser range, if you have access to EQ I don't see a reason for getting a 660S. The 600 is better when EQed and cheaper.

With that said, for critical listening I would also consider the Sundara. I own both of them (Sundara and HD600). The HD600 may be subjectively (and marginally) more pleasing for vocal and acoustic stuff, it has that kind of magical midrange texture that's hard to explain. But the Sundara is definitely more versatile if you listen to a lot of music genres, plus when EQed it goes lower than the HD600 without distortion.
  • HD600 Pros : price (< 300 €), performance when EQed, magical midrange, weight (only 260g)
  • HD600 Cons : doesn't go very low (even when EQed), not very versatile, very small soundstage, comfort is OK but not amazing, plastic build

  • Sundara Pros : decent price (300-350 €), performance when EQed (including bass down to 30 Hz), more versatile than the HD600, very precise treble, bigger soundstage
  • Sundara Cons : weight (372g, which remains reasonable especially for a planar, and the comfort is OK too, so not a big deal)... well, not a lot of cons actually.
Both will need an amp to drive them to their fullest potential. The HD600 is 300 Ohm, but I have found the Sundara to be more demanding, due to its low sensitivity (94 dB). That's also confirmed by solderdude's Headphone Power Table : the Sundara needs more power than the HD600 to reach the same SPL. But again, with an amp it won't be a problem, both headphones are relatively easy to drive with any decent amp.

After some months of listening, I have to recognize that the Sundara is indeed more versatile than the HD600. So ultimately I would recommend it for critical listening. There's a reason why many consider it the best headphone under 500 €. As for me, I'm very happy to keep both, because I can enjoy the HD600 on vocal and acoustic stuff, and switch to the Sundara for the rest. ;)
 
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#6
My thoughts on those cans:
I do not compare a HD600 vs. a HD660S. They are not similar in sound and also have different drivers. Although you can hear the typical Sennheiser signature sound out of both. And what is higher resolution? You can get a more resolving headphone for instance when you use a dac and headphone amp with very low noise and low distortion. Then pull up some upper mid and some highs and there you have it. In marketing it is called "higher resolution". :)
I can not get the HD660S get to sound like a HD600 with PEQs. Similar, but not equal. So they play different but can be very close with EQ'ing. So i came to the fact that they have a very different sound signature and it is worth to try out both or have both.

But, the HD600 is a good sounding headphone out of the box. And the HD660S is too. I like both. For my liking they sound better out of the box than every Beyerdynamic. But that's a personal taste, i would say. I switched from a HD700 to HD600 & HD660S. The HD660S uses the same or modified drivers from the HD700, as far as i know. But they sound very different. I use Harman target EQs with more bass and more lower warm mids. I don't like the dry Harman target EQ sound.

When it comes to a price... you don't pay for the material cost very much. You pay for researching that took years and marketing, ... and for a company that can deliver headphones for decades and that can deliver repair parts for your headphones.
I would say the other HD6's should have a higher price like the HD660S because other company like Beyer costs a lot more. And they are not better, ... only different in sound.
 

solderdude

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#7
The HD660S uses the same or modified drivers from the HD700, as far as i know
A myth I read everywhere. They are anything but the same driver. It's like saying the HD600 and HD650 have the same drivers because they look the same at first glance. It's a rumour and nothing but a rumour.
Yes, the part behind the driver looks similar to that used in the HD700, yes the magnet/frame used is the same as it is in the entire HD5xx series because Sennheiser. Yes, both have 150 ohm voice coils. Yet the membrane, the actual business end of the driver differs, order codes differ etc. It is also not true that the HD58x and HD660S driver are the same.

Otherwise I would agree with your assessment.
 
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#8
Ah, ok. This explains the huge difference in sound (660S = dark, 700 = ultra bright). I guess some points like the disappearing of the HD700 from the market and the new appearing of the HD660S which drivers look similar came to that rumour.
 
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#9


HD660S has a bit less clarity compared to the HD650 and HD600.
As most folks 'complained' about the over the top clarity of the HD600 (presence in the 3kHz area) this was 'solved' in the HD660S.

So a HD650 with less clarity.

They can be EQ'ed but not with impressively loud subbass EQ'ed in.
The small peak around 5kHz should be EQ'ed and one can EQ 30Hz about +5dB, 60Hz +1dB

HD660s have the most clarity of them all, HD600 are the most bright of them all and HD 650 are the most smooth ... Graphs are not always saying the truth . Neither reviewers ... People having all of them and have over 400 hours on them known better in my XP.
 
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#10
A myth I read everywhere. They are anything but the same driver. It's like saying the HD600 and HD650 have the same drivers because they look the same at first glance. It's a rumour and nothing but a rumour.
Yes, the part behind the driver looks similar to that used in the HD700, yes the magnet/frame used is the same as it is in the entire HD5xx series because Sennheiser. Yes, both have 150 ohm voice coils. Yet the membrane, the actual business end of the driver differs, order codes differ etc. It is also not true that the HD58x and HD660S driver are the same.

Otherwise I would agree with your assessment.
I think u are a little bit confused , with all respect .
HD660s use the Same driver with HD 700 , HD 600 and HD650 ( new ones) use the shame driver . All of them are just different tuned. I have all 5 and 6 series also the first one HD 600 drivers, HD 660s and HD 700 have exactly the same magnet pcb and blue coil wine . Sennheiser can also verify that to you with mail response .... So in the end are the HD 660s and HD 700 same driver ? Yeah they are , Are they sound different ? yeah for sure .

About HD58X and HD 660s they are for SURE different drivers , the use different magnet voice coil pcb , i have posted many photos of them side by side to prove that , and also they sound different , HD 660s has more detail better imaging better separation less bass less treble and overall smoother more capable driver.
 
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#11
My thoughts on those cans:
I do not compare a HD600 vs. a HD660S. They are not similar in sound and also have different drivers. Although you can hear the typical Sennheiser signature sound out of both. And what is higher resolution? You can get a more resolving headphone for instance when you use a dac and headphone amp with very low noise and low distortion. Then pull up some upper mid and some highs and there you have it. In marketing it is called "higher resolution". :)
I can not get the HD660S get to sound like a HD600 with PEQs. Similar, but not equal. So they play different but can be very close with EQ'ing. So i came to the fact that they have a very different sound signature and it is worth to try out both or have both.

But, the HD600 is a good sounding headphone out of the box. And the HD660S is too. I like both. For my liking they sound better out of the box than every Beyerdynamic. But that's a personal taste, i would say. I switched from a HD700 to HD600 & HD660S. The HD660S uses the same or modified drivers from the HD700, as far as i know. But they sound very different. I use Harman target EQs with more bass and more lower warm mids. I don't like the dry Harman target EQ sound.

When it comes to a price... you don't pay for the material cost very much. You pay for researching that took years and marketing, ... and for a company that can deliver headphones for decades and that can deliver repair parts for your headphones.
I would say the other HD6's should have a higher price like the HD660S because other company like Beyer costs a lot more. And they are not better, ... only different in sound.

I have the 5 ,6 and 700 from all of them i prefer 6 line the most , 600 are the most in your head vocals and so tight and pushed to me , HD 650 are smooth but without losing detail they have a warm tone to them that 600 doesnt have , And 660s are like something from both of them , they are for sure more detailed than 650 way better imaging and instruments separation but they lose this smooth veil that make bad recording sound so good on HD 650 . All of them are amazing headphones and sound signature is the same . It just those little things that someone will like or not , but in the end in my opinion the most capable is the 660s.

I never use EQ because i want to know exactly how a headphone sounds , when i chat with others and say my opinion .
 
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#13
Hi LaurenDean,

I had to face the same choice about 6 months ago. I ended up buying a HD600 and I'm glad I did. I think most people should, provided they have access to EQ.

The HD660S is clearly overpriced. The HD600 is much cheaper, and like 3125b wisely said, it can be EQed closer to the Harman curve (as shown by Oratory's preference score), so ultimately the EQed result will be 'better' if I dare put it that way.

About the Pros you mentioned, a) simply doesn't matter anymore if you EQ them. Just check the HD600 EQed frequency response : it's really hard to get any closer than that to the actual Harman curve. And b), no, I don't think the HD660S is more resolving than the previous models (I would need scientific evidence to back up that claim, not subjective impressions). So within the Sennheiser range, if you have access to EQ I don't see a reason for getting a 660S. The 600 is better when EQed and cheaper.

With that said, for critical listening I would also consider the Sundara. I own both of them (Sundara and HD600). The HD600 may be subjectively (and marginally) more pleasing for vocal and acoustic stuff, it has that kind of magical midrange texture that's hard to explain. But the Sundara is definitely more versatile if you listen to a lot of music genres, plus when EQed it goes lower than the HD600 without distortion.
  • HD600 Pros : price (< 300 €), performance when EQed, magical midrange, weight (only 260g)
  • HD600 Cons : doesn't go very low (even when EQed), not very versatile, very small soundstage, comfort is OK but not amazing, plastic build

  • Sundara Pros : decent price (300-350 €), performance when EQed (including bass down to 30 Hz), more versatile than the HD600, very precise treble, bigger soundstage
  • Sundara Cons : weight (372g, which remains reasonable especially for a planar, and the comfort is OK too, so not a big deal)... well, not a lot of cons actually.
Both will need an amp to drive them to their fullest potential. The HD600 is 300 Ohm, but I have found the Sundara to be more demanding, due to its low sensitivity (94 dB). That's also confirmed by solderdude's Headphone Power Table : the Sundara needs more power than the HD600 to reach the same SPL. But again, with an amp it won't be a problem, both headphones are relatively easy to drive with any decent amp.

After some months of listening, I have to recognize that the Sundara is indeed more versatile than the HD600. So ultimately I would recommend it for critical listening. There's a reason why many consider it the best headphone under 500 €. As for me, I'm very happy to keep both, because I can enjoy the HD600 on vocal and acoustic stuff, and switch to the Sundara for the rest. ;)

Let me tell you what i think as an owner of HD 600 ( the Ireland ones) 650 660s and Sundaras .

At My country Europe prices are 300 euro for 600 , 340 euros for 650 and 390 euros for 660s ( with balanced 4.4 cable) So prices are not the case.
I understand that In other countries 660s are expensive , but Thats life ... We cant get ELEX and 6XX also at prices that US people get them .

So HD 600 are amazing headphones and i really love their midrange is so so good and in your head i like that small soundstage and presentation , also HD 600 are more dry on bass region , overal amazing headphone that i never sell. But HD 660s have other qualities like way better imaging and separation i would say better than Sundara 2020 version new pads, and 660s have better texture on bass compare to 600 and 650 and way way faster when a lot of instruments hit at the same time . So is it an update ? It depends by what u looking for .

About HD 660s Vs Sundara also both great headphones Sundara sound more clinical more detailed than HD 660s and bigger soundstage , On the other hand HD 660s are more natural they dont have that (metalic Sundara sound) , HD 660s have detail but its not pushed to u like Sundara does its there but its presented smoother and on background , Timbre is also better on HD 660s so natural and warm compared to dry presentation of Sundara , Bass notes go deeper on Sundara but HD 660s doesnt go deep but u dont lose texture and progresion like some say .
About Comfort Sundara are heavier compare to 6 series but if u have small ears that dont touch the small cyrcle pads then i dont see any problem , HD6 series on the other hand pads are not soft when they are new they need hours to get softer and get the sweet spot , Those Hybrids Sennheiser Pads ( yeah they are hybrid they use 2 materials inside the driver synthetic leather and outside without stitches they use velur) need replacement after 1-2 years of use depending the hours of listening .

About build quality HD 6 series never brake this is known , also u dont have to be careful every time if they fall down or anything , With Sundara u have to be careful , cable is bad quality , pads in my unit had to be changed ( very good customer support) and also Sundara sound is effected a little bit by the air pressure of the environment , ( u can test that by just moving your hands outside of the driver effecting the air ) 129308762_10158911463572390_3022773793770257873_n.jpg
 

solderdude

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#14
HD660s use the Same driver with HD 700 , HD 600 and HD650 ( new ones) use the shame driver .
I guess the folks at Sennheiser development are confused as well and somehow don't seem to know what went in their headphones.
Obviously we have been talking to different folks at Sennheiser.

They do use the same magnet/frame, just like all new headphones do but are NOT the same drivers.
The order codes for spares differ as well. Why keep different order codes for the same driver.
If one puts a HD650 driver in a 600 frame it sounds and measured like a HD650 so why would those drivers be the same, they even have different power ratings. The LOOK the same... just like the new frame drivers LOOK the same yet they aren't.
 
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#16
I guess the folks at Sennheiser development are confused as well and obviously don't seem to know what went in their headphones.
Obviously we have been talking to different folks at Sennheiser.

They do use the same magnet/frame, just like all new headphones do but are NOT the same drivers.
The order codes for spares differ as well. Why keep different order codes for the same driver.
If one puts a HD650 driver in a 600 frame it sounds and measured like a HD650 so why would those drivers be the same, they even have different power ratings. The LOOK the same... just like the new frame drivers LOOK the same yet they aren't.

Ok just called Sennheiser official seller and asked via phone if my HD 660s and HD 700 use the same driver , and told me its based on HD700 driver with different tuning . I also open a ticket to be sure on Sennheiser Germany so i can have that written and copy paste it .

They do use the same magnet/frame and ( coil ??? i see it its exactly the shame and its a blue line that only 700 and 660s driver has that) , all the others from 5 and 6 line have red only coil and some other differences .

The order codes are different that make sense because they do have different tuning ... i guess this is what i understand different because clearly the 660s drivers if we put them on HD700 they will sound different even if they have different frame i get that i see your point .

What i understand is that for u a driver that has the same magnet, same membrane, same frame, same looks ,same coil , same pcb , same holes behind the driver ,but sounds different ( in the same frame and pads) is a different driver ....
But For me its the same driver with different tuning and i am not saying different tuning because of the frame , i speak for the driver and pcb only.

So lets agree u are right because they do sound different in the end of the day so technically u are correct .

Other than that it would be nice to see something from Sennheiser or someone else to prove that HD 660s driver and HD700 driver are not Physically exactly the shame for example the thickness of membrane or the power of the magnet ... until then...... :) .
 
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#17
forse non conosci Solderdude, questo è il suo sito https://diyaudioheaven.wordpress.com/
Oh i get it now ... All my respect to him then . I am always open to learn from him .
Great if he is on DIY audio Heaven it would be easy to get Official statement from Sennheiser that says they are (physical) different drivers...
Or even some measurements thickness from the the coil , membrane or power of the magnet ... etch etch . It would be great for everyone to know that.
Cant wait.
 

Berwhale

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#18
I'm very happy with my HD660S. I paid £262 from the Senheiser Outlet. UK prices for the HD 600/650/660S are £370, £400 & £430. So I got a pretty decent discount which I think outweighs any measured differences between the models.
 

solderdude

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#19
What i understand is that for u a driver that has the same magnet, same membrane, same frame, same looks ,same coil , same pcb , same holes behind the driver ,but sounds different ( in the same frame and pads) is a different driver ....
Yes, because these do not change the sound. By your logic the HD560S and all other current HD*** drivers (with similar impedance) are the same.
They aren't. Different membrane materials and perhaps different paper damping etc. is what makes the driver different.
The PCB, frame etc have no influence whatsoever.
Based on is not 'the same'.

Sellers generally have no real knowledge and depending on which Senn rep you talk to you might get 'commercial' answers.
I have been in contact with the development department (on a few occasions) regarding new models and asked them.

HD660S or Sundara ?
What's your favorite under specific conditions/music ?
Both are good headphones yet excel on different aspects.
 
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#20
Yes, because these do not change the sound. By your logic the HD560S and all other current HD*** drivers (with similar impedance) are the same.
They aren't. Different membrane materials and perhaps different paper damping etc. is what makes the driver different.
The PCB, frame etc have no influence whatsoever.
Based on is not 'the same'.

Sellers generally have no real knowledge and depending on which Senn rep you talk to you might get 'commercial' answers.
I have been in contact with the development department (on a few occasions) regarding new models and asked them.

HD660S or Sundara ?
What's your favorite under specific conditions/music ?
Both are good headphones yet excel on different aspects.
Now that i know your background , lets say that u know better . So the tune of the driver even if it looks the same , its all about these small difference that u said ? for example paper ,membrane are what makes the tune of the driver ?
About sellers thats true , i still remember when i order HD 250 BT told me that its the same driver like hd 25 and it was way different and bad in my opinion.

Hard to choose if anyone has any of other HD 6 series then its easy Sundara . If i had to choose only for 1 headphone then it will be HD 660s not because is perfect on something but because its good on everything .
When i go from HD 660s to Sundara i get that feeling of more detail pushed to me more airiness more progression on low end notes and always i say wow this sounds more clean and every instrument has so much distance between and feels amazing .
When i go from Sundara to HD 660s the first 5 minutes makes me say oh that is not exciting , after more listening what i hear is the instruments feel more realistic blend together better without this big air , also detail is there but they are not pushed to me , i have to push my self to listen them on background , the timbre is something that feels realistic also vocals are like u are there with the singer in front of your and everything else a little back in a close room , imaging is perfect on left right mostly its pin point , on Sundara its there but its like u have a more space to locate the sound .
If i can describe it better Sundara are like a track that is mastered inside a studio and sounds so clean and polished that makes it great but processed and unnatural metalic . With HD 660s its like an analogue sound not polished not so detailed and fast but more natural and what someone will expect from an instrument sound in real life up close .
So its all about taste mostly ...
Sorry for my bad english.
 
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