Headphone Measurements Using Brüel & Kjær 5128 HATS

[DualTriode]

Hello All,

I believe that amirm bought the GRAS 45CA because it is state of the art, not because it is cheaper.

I do not believe that there will be a monetary return. It was a purchase rather than an investment.

I look at the instruments in my cage; I never expect to make a dime. I am addicted to fun and learning.

Thanks DT

 

[Dreyfus]

The 5128 HATS is technically more advanced than the other systems which still use iterations of the old IEC 711 ear simulator that was originally designed for hearing aids 40 years ago. Instead of just damping (masking) the unwanted high Q peaks caused by the nature of the open tube resonator they decided to redesign the simulator and bring it closer to the anatomy of the human ear. It has a smaller diaphragm being closer to the size of the human ear drum, no unnecessary long canal extension and is capable of resolving up to 20 kHz (instead of only 10 kHz) just by design. Their reference impedance for the middle ear is an average of least 20 in-ear measurements, where the old 711 is only based on two sets of data (actually those of the engineers who invented it). They also came up with their newer anthropometric ear canal, of course, averaged over 40 MRI scans.

The 45CA is more established (hence easier to compare) because it is cheaper, but certainly not state of the art.

Regards
Dreyfus

 

[DualTriode]

Hello All,

Before posting I went to merriam-webster.com the international standard IEC 60318-4 is by definition State of the Art.

Thanks DT

https://www.merriam-webster.com/dictionary/state of the art

 

[amirm]

The 5128 HATS is technically more advanced than the other systems which still use iterations of the old IEC 711 ear simulator that was originally designed for hearing aids 40 years ago. Instead of just damping (masking) the unwanted high Q peaks caused by the nature of the open tube resonator they decided to redesign the simulator and bring it closer to the anatomy of the human ear. It has a smaller diaphragm being closer to the size of the human ear drum, no unnecessary long canal extension and is capable of resolving up to 20 kHz (instead of only 10 kHz) just by design. Their reference impedance for the middle ear is an average of least 20 in-ear measurements, where the old 711 is only based on two sets of data (actually those of the engineers who invented it). They also came up with their newer anthropometric ear canal, of course, averaged over 40 MRI scans.

All of this is true in theory. In practice, smallest variations in how you seat the headphone will make radical changes in high frequency response. What extra accuracy you get from the coupler/pinna will very well get lost in there. I also found it very difficult to get a fit on the 5128 and come close to the measurements others have.

The biggest issue is that there is no Harman target curve for it so you don't know what you are measuring.

Now, if you are developing headphones and get used to the fixture and are making relative changes, then it is fine. As it is, it is not suitable for a reviewer like me. Otherwise, I would have bought it regardless of the extra expense over GRAS 45CA.

I should say that I was most impressed with the company behind the unit and the superb support I received during my evaluation. And may get one at some future date. But for now, the decision to get the 45CA was definitely the right one.

 

[Dreyfus]

international standard IEC 60318-4 is by definition State of the Art

The 60318-4 still refers to the old 711 design. I am afraid to say that it is outdated.

In practice, smallest variations in how you seat the headphone will make radical changes in high frequency response. What extra accuracy you get from the coupler/pinna will very well get lost in there. I also found it very difficult to get a fit on the 5128 and come close to the measurements others have.

The 5128 HATS might show more variance in correlation with headphones because it is closer to the complex anatomy of human. Its intention is not to generally simplify or even suppress effects like canal resonance or leakage, which the 45CA platform certainly does in some aspects.

The crux of the matter is also that the more "accurate" you get at simulating a human ear the less representative small, exemplary sets of data will be. As with in situ measurements you have to gather a lot of data with varying seating positions and then generate the average. It creates a little more effort at the first moment but will reward you with practically more stable and reliable data in the long run.

The biggest issue is that there is no Harman target curve for it

That is not too regrettable IMO.
Observing the statements and converstations in the forums I think that it generally adds more confusion than unanimity. To me that is a clear sign that the community is not ready for such targets, yet. We need more critical enlightenment as a basic prerequisite to avoid misinterpretation of headphone measurements. If you ask me, this is the real challenge of our doing: the mediation between science and the general public.

so you don't know what you are measuring

Why should that be the case? Measurements are still differential.


Regards
Dreyfus

 

[DualTriode]

Hello All,



“In practice” is what is relevant.

You can have undocumented bloody edge state of the art or tried and true state-of-the-art from a usage standpoint. (This is a common legal argument, Tried and True wins.)

For the purpose of review and comparison the “Industry Standard” is the tool of choice.



Thanks DT

 

[Dreyfus]

Looks like we have divergent ideas of science then.

Regards
Dreyfus

 

[Robbo99999]

The 60318-4 still refers to the old 711 design. I am afraid to say that it is outdated.


The 5128 HATS might show more variance in correlation with headphones because it is closer to the complex anatomy of human. Its intention is not to generally simplify or even suppress effects like canal resonance or leakage, which the 45CA platform certainly does in some aspects.

The crux of the matter is also that the more "accurate" you get at simulating a human ear the less representative small, exemplary sets of data will be. As with in situ measurements you have to gather a lot of data with varying seating positions and then generate the average. It creates a little more effort at the first moment but will reward you with practically more stable and reliable data in the long run.


That is not too regrettable IMO.
Observing the statements and converstations in the forums I think that it generally adds more confusion than unanimity. To me that is a clear sign that the community is not ready for such targets, yet. We need more critical enlightenment as a basic prerequisite to avoid misinterpretation of headphone measurements. If you ask me, this is the real challenge of our doing: the mediation between science and the general public.


Why should that be the case? Measurements are still differential.


Regards
Dreyfus

To me, the biggest issue with this B&K was that there was no target curve for it that was in the same vein as the Harman Curve. I think there was a Free Field & Diffuse Field Target that came with it, and Mad_Economist worked out a theoretical type of "Harman Curve" using the Chris Struck Method to combine the Free Field & Diffuse Data with I think the reverb characteristics of the Harman room (might be wrong about the last point).....but it was calculated rather than measured, and myself personally I was not able to experience the validity of that combined with the B&K measurements because I don't own any headphones that were measured on it so couldn't listen to the combined results.....but either way it's not as "bonafide" as the Harman Headphone Curve and the GRAS gear it was made on. For me, the most important aspect of the measurements is that they can be used to create EQ's, and the B&K just didn't have that solid backing. It might well be more accurate than the GRAS, but it doesn't really mean anything if we've not got a proven target to aim for. The GRAS unit that Amir got solves that conundrum a lot closer.

 

[Dreyfus]

I get the point. I just value a good measurement system that is based on the most recent science more than an older system which is maybe not at eye level technically but comes with a somewhat established (p)reference curve.

If you look around in the community you will notice that the subjective agreement on the Harman Headphone curve is still a bit controversial. And it is not just a lot of (end) users who prefer subjective modifications. Also the engineers who make such measurements do often publish their own tagets. Some of them are only slight balance changes around the Harman curve. And some of them do promote their own idea of "neutrality" which comes with much less bass and a different weighting of mids and treble.

All of that does not mean that the target itself is fundamentally wrong and has no scientific foundation.
Still, the practical variance we see out there - which is due to individual ear geometry, taste, circle of confusion and all the other factors that have been thoroughly discussed before - is enough for me to doubt that the approach of a specific singular curve is stable enough (yet) to qualify as a common standard for both the average and especially the hi-fi community. This situation can be proved by the very simple observation that nearly every thread that shares FR graphs together with the Harman curve as a reference is - at least temporarily - subject to fundamental debates about perceived neutrality and the validity of Harman. Just searched a few threads for the buzzword "harman": HD800S review: 5 of 29 pages; HD650 review: 4 of 15 pages; Focal Clear Review: 3 of 25 pages.

Maybe some people expect the works of Harman to break the circle of confusion and arbitrariness of taste some day. Personally, I do not think that this is going to happen. At least not to the extent that it solves all the essential problems. Just consider the retrospective of music productions or the practical arbitrariness of most speaker/room responses. You cannot fix the reality by just claiming a specific curve to be the reference!

All this arbitrariness leads me to the conlcusion that we are not quite there with the approach of a singular (Harman) target, yet, and that we need better technology and more reasearch to improve in our field. And I think that the 5128 HATS might be a good choice to get at least one step closer to a next generation of headphone measurement. Remaining in an established ecosystem may be practical thing, but it is a technical limit after all.

Regards
Dreyfus

 

[Robbo99999]

I get the point. I just value a good measurement system that is based on the most recent science more than an older system which is maybe not at eye level technically but comes with a somewhat established (p)reference curve.

If you look around in the community you will notice that the subjective agreement on the Harman Headphone curve is still a bit controversial. And it is not just a lot of (end) users who prefer subjective modifications. Also the engineers who make such measurements do often publish their own tagets. Some of them are only slight balance changes around the Harman curve. And some of them do promote their own idea of "neutrality" which comes with much less bass and a different weighting of mids and treble.

All of that does not mean that the target itself is fundamentally wrong and has no scientific foundation.
Still, the practical variance we see out there - which is due to individual ear geometry, taste, circle of confusion and all the other factors that have been thoroughly discussed before - is enough for me to doubt that the approach of a specific singular curve is stable enough (yet) to qualify as a common standard for both the average and especially the hi-fi community. This situation can be proved by the very simple observation that nearly every thread that shares FR graphs together with the Harman curve as a reference is - at least temporarily - subject to fundamental debates about perceived neutrality and the validity of Harman. Just searched a few threads for the buzzword "harman": HD800S review: 5 of 29 pages; HD650 review: 4 of 15 pages; Focal Clear Review: 3 of 25 pages.

Maybe some people expect the works of Harman to break the circle of confusion and arbitrariness of taste some day. Personally, I do not think that this is going to happen. At least not to the extent that it solves all the essential problems. Just consider the retrospective of music productions or the practical arbitrariness of most speaker/room responses. You cannot fix the reality by just claiming a specific curve to be the reference!

All this arbitrariness leads me to the conlcusion that we are not quite there with the approach of a singular (Harman) target, yet, and that we need better technology and more reasearch to improve in our field. And I think that the 5128 HATS might be a good choice to get at least one step closer to a next generation of headphone measurement. Remaining in an established ecosystem may be practical thing, but it is a technical limit after all.

Regards
Dreyfus

I think we're never gonna be completely there due to the circle of confusion you mentioned. The day that all recording studios have to have their gear EQ'd to an established Target Curve is the day where the circle of confusion could end - in terms of consumers then being able to EQ to the established Target Curve. If there continues to be no fixed standards for speaker sound during music creation, then we're never gonna be truly exact on experiencing "what the artist/recording engineer envisaged"....and that's true for both speakers & headphones, but more so with headphones for all the reasons we know & discuss.

I think ideally the Target Curve for music producers should be similar to what is achievable with anechoically flat speakers in a somewhat normal room.....so the Harman Curve is really not far off that, but I think it should be fairly similar to what can be relatively easily achievable in people's homes.

 

[thewas]

I think ideally the Target Curve for music producers should be similar to what is achievable with anechoically flat speakers in a somewhat normal room.....so the Harman Curve is really not far off that, but I think it should be fairly similar to what can be relatively easily achievable in people's homes.

Thankfully the trend also in current studios goes to good monitors (thus anechoically flat and with smooth directivity) mainly EQed at the bass and an average and relative frequency independent room reverberation so we slowly get out of the circle of confusion which to my experience shows in many modern recordings which don't show as large tonal variation as in the past, so there is some light at the end of the tunnel.

 

[Dreyfus]

The day that all recording studios have to have their gear EQ'd to an established Target Curve is the day where the circle of confusion could end - in terms of consumers then being able to EQ to the established Target Curve.

That is definately possible. But what about the retrospective mentioned above? What about those listening mainly to music produced in the 20th century? A consistent standard could establish a new era, but it cannot "fix" history.

Also, do not forget the lack of working HRTF and seal compensations for most headphones build today. That is just another field we have to grow in.

If there continues to be no fixed standards for speaker sound during music creation, then we're never gonna be truly exact on experiencing "what the artist/recording engineer envisaged"

Imo that is a very ungrateful concept.

Regards
Dreyfus

 

[Robbo99999]

That is definately possible. But what about the retrospective mentioned above? What about those listening mainly to music produced in the 20th century? A consistent standard could establish a new era, but it cannot "fix" history.

Also, do not forget the lack of working HRTF and seal compensations for most headphones build today. That is just another field we have to grow in.


Imo that is a very ungrateful concept.

Regards
Dreyfus

Yes

 

[bluefuzz]

What about those listening mainly to music produced in the 20th century? A consistent standard could establish a new era, but it cannot "fix" history.

History doesn't need fixing.

While I want my headphones and other hifi gear to reasonably accurately reproduce what is on the tape/cd/vinyl/stream, I couldn't really give a fig as to how the recording in question was produced or mastered – or how 'accurate' was the gear on which it was made. Whether it truly represents 'what was heard in the control room' is irrelevant to the musical experience IMO.
The vast majority of music worth listening to recorded in the last 100 years was recorded and produced by people who, for the most part, were making it up as they went along and probably didn't have much of a clue what they were doing or what anything 'should' sound like. Often they just made do with what was in hand or even consciously 'did it wrong'. That's what makes it interesting!

We should be wary of conflating accuracy of REproduction with the actual artistic production where anything goes - and should hopefully continue to go.

We don't criticise a Rembrandt because it was painted by candlelight and not by an ISO certified 6500 Kelvin light source. It is what it is ...

 

[amirm]

That is not too regrettable IMO.

Not at all. You are wondering around in the dark without it. I know, I tried the 5128 and that is what I faced. With GRAS, that problem almost completely vanished.

Observing the statements and converstations in the forums I think that it generally adds more confusion than unanimity.

People are confused because there has not been a proper advocate and approach to testing headphones this way. Nothing different than when I started to measure speakers. This is why I started to measure headphones. The tools have to be used properly and right approach taken to test things.

Anyway, I extensively used and compared the 5128 to 45C. I know what I know about both in trying to correlate listening test results with measurements. To the extent we are going to approximate the measurements to draw useful inferences, we don't need higher accuracy out of them. The 45C simply does the job more appropriately, easily and with less money.

There is also another great benefit to 45C: that is what the industry has, not 5128. So to the extent there are disputes about measurements, they can be resolved much easier than dealing with a new measurement rig.

 

[DualTriode]

Hello All,

An interesting and true story about measurement accuracy:

My mother-in-law was the accomplished seamstress. She could measure the person and fabric to produce a dress, shirt, or pair of pants quite efficiently. The stuff would fit well.

One day I saw her stretched out tape measure on the floor so I put my Stanley alongside. Her 60 inch tape measure was 66 inches long.

It worked well for her.

Thanks DT

 

[Feelas]

History doesn't need fixing.

While I want my headphones and other hifi gear to reasonably accurately reproduce what is on the tape/cd/vinyl/stream, I couldn't really give a fig as to how the recording in question was produced or mastered – or how 'accurate' was the gear on which it was made. Whether it truly represents 'what was heard in the control room' is irrelevant to the musical experience IMO.

"What was heard in the control room" informed most of the mastering & mixing job, the panning of sounds, EQ used to uncover some details, the reverb and direct signal balance and so on, and so forth - disregarding this is a big mistake!

Having interned now for a longer while on some areas regarding benchmarking servers, it's easy to understand why @amirm is using GRAS and it's been said many times before here: it's not about the undocumented bleeding edge, it's about being able to share, discuss & check- that's what most of the science is about, after all. Doing benchmarks it's most of the time some legacy and/or last year version, not merely the most alpha on the market - simply because there's nothing to compare with.

Hello All,

An interesting and true story about measurement accuracy:

My mother-in-law was the accomplished seamstress. She could measure the person and fabric to produce a dress, shirt, or pair of pants quite efficiently. The stuff would fit well.

One day I saw her stretched out tape measure on the floor so I put my Stanley alongside. Her 60 inch tape measure was 66 inches long.

It worked well for her.

Thanks DT

Systematic error you can account for & include the bias. Random error, on the other hand, is impossible to correct.

 

[Dreyfus]

People are confused because there has not been a proper advocate and approach to testing headphones this way.

Which approach exactly, if I may ask?

I think that Oratory and Crinacle have done a pretty good job with their rigs and explinations, so far.

Regards
Freyfus

 

[amirm]

Which approach exactly, if I may ask?

I think that Oratory and Crinacle have done a pretty good job with their rigs and explinations, so far.

What is a pretty good job? I thought you said Harman preference curve has caused confusion. If so, and they are behind promoting it then by your definition they have not done a good job.

Part of the problem has been presentation of information and analysis. I am dead against throwing a bunch of measurements out there and then ending with a 10 band EQ. This is not the way to teach, nor are those 10 band EQs justified. Contrast that approach with my reviews so far where a story is told that starts with specific measurements and ends with appropriate subjective evaluation and simple equalization. It is an integrated, end to end story that holds together and builds on the foundation of Harman research but adds to it. You have to bring people along in each review.

 

[Palex]

What is a pretty good job? I thought you said Harman preference curve has caused confusion. If so, and they are behind promoting it then by your definition they have not done a good job.

Part of the problem has been presentation of information and analysis. I am dead against throwing a bunch of measurements out there and then ending with a 10 band EQ. This is not the way to teach, nor are those 10 band EQs justified. Contrast that approach with my reviews so far where a story is told that starts with specific measurements and ends with appropriate subjective evaluation and simple equalization. It is an integrated, end to end story that holds together and builds on the foundation of Harman research but adds to it. You have to bring people along in each review.

Dear Amirm, you carry out huge work. Don't pay attention to any critics. "Dogs bark, the Caravan goes"