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This has nothing to do with the topic at hand. It is not like Jude referenced those measurements in his answer.
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HBK Headphone Measurement Talks from Head-Fi and Sean Olive
- Thread starter amirm
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It's a bit frivolous to imply mud slinging by @amirm towards Jude' comment about having heard HE-1. Reality is that Jude could've phrased a better response to the question about his preference in headphones instead of feeding a feeble response. The context of the statement made at a measurement' forum obviously is what makes Jude' comment oxymoronic.
AudioManNewb
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People are right to doubt that just because you have listened to 100+ headphones and measured many means nothing. Personal experience means nothing. You can not be truly objective if you have a favorite headphone. Also how you were feeling when you listened to other headphones and how they fit on you plays a very important role in how they sound. Also you known they are very expensive headphones the HE1 going into the listen and there is a whole experience that goes into a audition of one. People come out with very favorable reviews of it because they are an experience beyond just the sound. It is hype and people fall for it. If there was something so grand about the sound and they are the pinnacle of greatness they would price it affordably as to make a profit.
solderdude
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People can doubt me, or any other person who heard it and has a personal opinion, but in the same breath of air generally do trust their own observations of that of people they trust explicitly.
I have multiple favorite headphones. I also heard headphones I would never pay the asking price for. Some were excellent others were not.
Yes, totally agreed on this. The first one (personal state as it were) is of less importance when you can compare directly to a well known headphone and know how actual instruments sound.
Not in my case... I just saw it and I could have a listen in good circumstances. I did not anticipate on auditioning it. I kind of hoped it did not sound as good as it did.
Yes for many it will be, just like any new headphone reviewed by famous YT reviewers that are chosen because they are ALWAYS positive.
Was not the case for me IMO. I did not care but when the opportunity was there to have a listen I too it. Never was interested in it anyway and assumed I would never hear one.
But again... don't take my word or anyone else's word for it. Have a listen for yourself some day in relaxed circumstances without anticipation of sound and make up your own mind. Maybe you already did and did not like it.
And.. experience with many headphones from crap to many TOTL does help in recognizing proper sound. It's not that I only use one favorite headphone and measure all against one that I personally like.
I have multiple favorite headphones. I also heard headphones I would never pay the asking price for. Some were excellent others were not.
Yes, totally agreed on this. The first one (personal state as it were) is of less importance when you can compare directly to a well known headphone and know how actual instruments sound.
Not in my case... I just saw it and I could have a listen in good circumstances. I did not anticipate on auditioning it. I kind of hoped it did not sound as good as it did.
Yes for many it will be, just like any new headphone reviewed by famous YT reviewers that are chosen because they are ALWAYS positive.
Was not the case for me IMO. I did not care but when the opportunity was there to have a listen I too it. Never was interested in it anyway and assumed I would never hear one.
But again... don't take my word or anyone else's word for it. Have a listen for yourself some day in relaxed circumstances without anticipation of sound and make up your own mind. Maybe you already did and did not like it.
And.. experience with many headphones from crap to many TOTL does help in recognizing proper sound. It's not that I only use one favorite headphone and measure all against one that I personally like.
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Using the harman target for the 45ca on the b&k system ist wrong because of the already mentioned reasons.
However given the circumstances how it was created, I don't see any reasons why we can't make that conversion to other systems. Let me explain why I think that way.
The harman target was created by given multiple headphones to multiple people and they should eq them to their preference.
Now first of all, all of those headphones really do sound different to different people. Some differ more, some less. Depends on how much it interacts with the human pinna.
Once the headphones were eqed, they were put on a fixture to measure to what target they had been corrected.
If they had put those headphones on a b&k system, they would have created the curve for that system but they chose the gras one.
Since the research is done and testing over, we could indeed use headphones (at best the some as in the test, but again, this shows what had an impact to the curve) and put those on the b&k system and see how they measure.
Some will definitly measure differently and the conversion factor will differ between headphones, but that is due to the fact that all headphones react different to human ears and is not a reason the measurement must be wrong.
The harman target is in an averaging over several measurement anyway.
If we don't accept the fact that there are several correct but different measurements, we lie to ourselfs. (but there are many wrong measurement, like unedited harman target on b&k)
There is indeed no real 'clean' measurement of the headphone only, since it always interacts with the human ear and those differ between fixtures as @sax512 pointed out correctly
ps. I wish this would be dicussed in it's own thread
However given the circumstances how it was created, I don't see any reasons why we can't make that conversion to other systems. Let me explain why I think that way.
The harman target was created by given multiple headphones to multiple people and they should eq them to their preference.
Now first of all, all of those headphones really do sound different to different people. Some differ more, some less. Depends on how much it interacts with the human pinna.
Once the headphones were eqed, they were put on a fixture to measure to what target they had been corrected.
If they had put those headphones on a b&k system, they would have created the curve for that system but they chose the gras one.
Since the research is done and testing over, we could indeed use headphones (at best the some as in the test, but again, this shows what had an impact to the curve) and put those on the b&k system and see how they measure.
Some will definitly measure differently and the conversion factor will differ between headphones, but that is due to the fact that all headphones react different to human ears and is not a reason the measurement must be wrong.
The harman target is in an averaging over several measurement anyway.
If we don't accept the fact that there are several correct but different measurements, we lie to ourselfs. (but there are many wrong measurement, like unedited harman target on b&k)
There is indeed no real 'clean' measurement of the headphone only, since it always interacts with the human ear and those differ between fixtures as @sax512 pointed out correctly
ps. I wish this would be dicussed in it's own thread
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I might be mistaken, but I don't think that Jude ever presented a 5128 measurement with Harman's GRAS target. If you're referring to slide 90 of Sean Olive's presentation, I believe that this is an addendum by the presentation's author to illustrate the inadequacy of the GRAS target on the 5128, not something that Jude himself produced.
You are totally right. Had that wrong in mind.
Deleted because wrong and not the main topic anyway.
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Me too. But that would disrupt the status quo, to a certain degree. I found out that a lot of people seem to have an almost emotional attachment to the status quo of things around here, be it measurement of headphones, speakers, rigs to use or curves to comply to.
To me disruption and second guessing is what gives Science its rightful name and generates progress. But I definitely seem to be in the minority.
So I fear that that thread would be a few posts of genuine content value by people like you, in a sea of noise by the defendants of the status quo.
Which is why I had great hopes when I signed up, but I'm slowly but surely using this site more and more as a second Gearslutz, just as an endless source of lulz.
At least the DACs and amps measurement section is solid, though.
(That's not how Harman came up with the Harman Target, following is a link to a pdf presentation from Harman that covers "everything")
I went it trough but still I'm pretty sure that's how it was done.
On page 39 is the test software with which modify the sounds and the results which are averaged later are measured on a 45ca.
Am I still wrong?
My understanding is that they measured the GRAS dummy head (at eardrum position) in their listening room with a couple of highly rated high quality stereo speakers (anechoic flat) at an ideal equilateral triangle listening position - so this created their baseline eardrum frequency response target. They then EQ'd that target into AKG K712 headphones and distributed this EQ'd headphone to their test subjects who were given bass & treble tone controls which they could tweak to their desired level of what sounded best to them. They then accumulated all the results of where the test subjects ended up at and this was the Harman Curve we know. There's a 2013 Harman Curve, a 2015 Harman Curve and a 2017 Harman Curve, they used trained listeners for creating the 2013 Harman Curve I think, and I'm not entirely sure what groups they used for 2015 & 2017, but I'm pretty sure 2017 is a mixture of untrained & trained listeners.
EDIT: I might have gotten confused as to which headphone was used as the simulator headphone, K712 might have been used in one of their studies to replicate a load of other headphones, so praps that one wasn't used in the Target Creation Experiments.
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I see.. I thought that room curve was just a starting point to begin with.
But the controls were for bass and treble only..
Yeah you are right.
And true that makes the conversion between different fixtures too vague.
I only couldnt' agree on that point that the conversion can not be right because different headphones measure different on several fixtures.
Thats's life with headphones.
Yes, the baseline dummy head measurement was the starting point, and then the bass & treble was tweaked to preference by the participants within the study.
I haven't talked about converting targets & measurements between fixtures super-recently in this thread, I did talk about it in this post on Sunday though: https://www.audiosciencereview.com/...from-head-fi-and-sean-olive.27017/post-929074
A very good point, Robbo! It's very hard to assess anything in a vacuum. Or simply from memory.
I wish HBK would post these conferences on their YT channel or somewhere else, btw, so the rest of us could see and hear them.
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Your in-ear measurement closes off the ear canal an effectively stops the AMTS from eliminating the 9K spike, in short your measurement method does not reproduce what you'd hear at the ear because your mic blocks the ear canal. AMTS quarter wave resonators assume the ear canal is there. Since listeners have ear canals this measurement method is useless for Stealth's highs. Unless the mic is at the ear drum you are actually forcing a bad response.
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I'm glad somebody starts to recognize this simple fact of physics, finally.
But the key thing is that the error in the response is direction dependant. If it wasn't, it wouldn't be as bad. You could just account for that with a correction EQ.
But it is, therefore you can't.
Same concept applies to measuring speakers response with a 'binaural' microphone which has half of its head chopped off.
Ideally we should even account for the torso!
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Bruel & Kjaer (BK), makers of precision acoustic measurement products, had a nice two day virtual conference. I wanted to listen to a bunch of them but had a major conflict. Fortunately, I watched two talks related to headphone measurements:
First one was by Jude Mansilla of Head-fi with the curious title of, "Audio Measurements As Consumers Content."
The second was from Dr. Sean Olive of Harman, going through his standard presentation on headphone preference but also a new research addition: difference between various headphone measurement gear relative to the one they used in their research. Specifically we were treated to the first analysis of BK 5128 which Head-fi has adopted as their standard.
Jude Presentation
I was very surprised and disappointed in most of this presentation. Bulk of time was spent showing and ridiculing the DIY measurement rigs members of his own forum had created. He showed pictures of them and while correctly stating some issues with them, I just could not figure out what he is after. Hobbyist are creating these measurements because headphone companies are not providing them. If Jude wanted to improve things, he should have complained about lack of such measurements from that sector which would be likely to be in this conference, than DIY people. I personally admired the work and creativity people had put in building their various fixtures.
Fortunately the second half of the talk was better in that he showed a bit about how they measure headphones which seems to be following what Tyll did with use of square wave and such. I am personally not a fan of driving headphone or speakers with square wave, especially a low frequency one. This can be hard on the transducer with the long duty cycle essentially being DC. I saw little justification for this method other than a hack to show the frequency response, sort of, using crude FFT.
The other thing he mentioned is that they no longer calibrate at one frequency and instead use white noise. I don't understand the merit of this either as matching the measurements to target needs to be done in a way that relates to the research. Credit to him he asked for feedback from audience but none was provided. Target matching is a visual thing for humans anyway so ultimately it doesn't matter per se.
I finally got an explanation of why they spent so much money on the Herzan isolation chamber. I am able to make measurements with better noise floor than them in my office with no isolation chamber. Answer is that they work in a noisy and busy office building and without noise isolation, they would have fair bit of pollution. In their typical promotion, they always made it sound like this was an essential thing in any measurement system rather than being a requirement in their noisy environment. We are fortunate to live far from civilization so have the quietness most of the time sans the delivery truck and our dogs barking because of that. I do my acoustic testing at night which eliminated this issue. Anyway, having an isolation chamber is not a bad idea but context is important and was not stated until now.
In QA section he was asked what his favorite headphone was. He said the Sennheiser HE-1 ($45,000). He was asked if he had measured it. Shockingly he said no! Gosh that was awkward when you are in a measurement seminar and you don't believe in this stuff to practice it.
Along these lines, he was asked if he felt listening tests were needed in headphones once you have measurements. He said no but could not provide any reasoning why.
Dr. Olive Presentation
As I noted, the meat of the presentation was a new research project to go back and remeasure a 20 headphones against half a dozen HATS and measurement gear. They only disclosed the difference between the modified GRAS 45 that they had used and BK 5128 which happened to be the one I, we are all interested in. The results were fascinating.
The BK 5128 underreported bass frequencies by substantial amount and in a sloping way. The lower the frequency, the less it reported the bass energy. This caused the preference score of a headphone drop 45 points from high 80s down to 40s! There were also some differences in high frequencies but that was not that meaningful or emphasized in the presentation.
They developed a compensation curve for 5128 relative to Harman target but alas, not all headphones showed the same differential. Using this new target, the above headphone showed an error of I think 6 points. But there are others that cannot be fixed this way.
To summarize, there is no way to use the Harman target curve 100% reliably when performing measurements using BK 5128! You can get close for majority of cases if you compensate but not all. And there could be effect on headphones that were not measured in the study.
So the overlaying that Jude does at head-fi with Harman target is totally wrong and inappropriate for bass energy.
As a proof point, Sean actually pulled my measurements of the Dan Clark Stealth and compared it to Jude's:
Mine:
Judes:
View attachment 156436
He matched the sizes and played with the reference levels to get an apple vs apple comparison. It clearly showed deficiency in bass measurements which he could explain with their research. But Jude's also showed a deficiency in the 3 to 6 kHz which I have circled in read which Sean and team could not explain. The dip does not show up in my measurements. That seems to be a measurement error in Jude's measurement but of unknown cause right now.
This is a fairly big setback for Head-fi headphone measurements based on BK 5128. No benefit was identified in using it, and problems identified with what it does produce. Fortunately some of it can be fixed and I hope Jude adopts the modified curve as to reduce confusion that his measurements can create relative to Harman research and comparison with measurements that the rest of us are performing.
I have been making this point for quite a while that more precision in some measurement doesn't do you any good if you don't have a yardstick to compare it to. And that seems to be the case with BK5128. I think fair bit of the research money in development of that fixture should have gone toward creating realistic target curves for it. Without it, the hype has gotten ahead of its true value putting head-fi in a difficult situation right now.
I felt bad for Jude as Sean's presentation was right after his. He had just finished singing the praises of BK5128 but all he showed for a proof point was the same IEM measurements he has been showing and how an IEM they tested was bright and GRAS measurement didn't show it but BK5128 did (or the reverse, can't recall exactly which).
Sean was also asked about his favorite headphones and he mentioned a couple that were in under $200 range.
When he covered the difference bass preferences, he was asked what they target. He said that the JBL line is boosting the bass a couple of dBs with the assumption that younger crowd were buying so were more inclined to want more bass. AKG line was staying true to the target bass response.
One sour note was Samsung Legal censoring one of his slides. And the fact that the company's policy has become to make sure competitors are NOT taught how to compete with Harman as they disclose their research. This means we will not hear as much as we have heard in the past about their work. I can see why Samsung has taken this position from business point of view, but for the rest of us, it is not a good development.
I hope Samsung management/Legal understand that by sharing their research, their work has become a review criteria which can be very beneficial to them.
That's all I remember to post. I have asked HBK if they will provide on-demand versions of these presentations but I have not heard back.
I'm late to the party. I'll catch up on the previous posts sooner or later, but I just read this and I wanted to provide a possible explanation for the lack of bass and different high frequency shape.
I apologize if somebody already did.
The 5128 employs a mic capsule that supposedly matches the eardrum's own acoustic impedance. The eardrum has less sensitivity at low frequencies, therefore the lower curve in that area.
For the highs, instead, the difference is partly due to said impedance and partly due to the fact that the ear canal in the 5128 is completely anthropomorphic, while GRAS's is only accurate up to about 1 cm, with the rest of the canal continuing as a cylinder.
The eardrum impedance matching by the 5128's capsule is, by its own nature, a lumped direction independent parameter, so that part could easily be accounted for by a correction EQ, for ALL headphones.
But the canal shape is a distributed direction dependant parameter, so that can't be corrected with a one size fits all EQ.
The fact that you 'discovered' that target translation can't happen among rigs is therefore not surprising at all (I've been saying that for a long time myself, but whatever...).
The assumption that this proves that the GRAS rig is more 'true' because of the preference scale drop is only a superficial analysis.
Once a target curve is provided for the 5128, it will be most likely 'truer', and definitely not any less accurate than GRAS's one.
But once again, GRAS's rig IS the most readily usable rig at the moment, given the 5128's absence of said target curve.
There is value in the measurements you do. I even feel confident to say it is probably the highest value possible at the moment, speaking in practical terms.
But it is definitely not the highest value possible in absolute. All it takes is for B&K to produce a target curve.
I have no idea what's taking those guys so long.
If I worked there I would get that done in a couple weeks, tops.. And I'm fairly lazy.
Weird.
But if I understand you well, that would result int the same variation in bass response for all headphones ? Sean Olive provided in his presentation the individual measurements for the 20 headphones measured and there were quite a few significant variations in the variation
.Headphones like the K550, DT770 pro, etc. showed a significant drop in response below 200-300Hz on the 5128, shaped in a way that's quite similar to seal deterioration, but other closed headphones (Bose, measured passively, for example), didn't exhibit a particularly strong change. Most open headphones such as the HD650, Utopia or HD800 showed a very moderate tilt below 1kHz, but the K701 showed a sharp drop as well.
I'm not certain that a single cause is at play here.
Could you elaborate on the bolded part ? By "highs", what range of frequencies do you mean ?
What I noticed is that in the 1-5kHz range some headphones such as the HD650 translated between the GRAS and 5128 fixtures with their FR curve shaped in a very similar way (you could normalise it at, let's say, 3kHz, and the two curves would mostly overlap), while others such as the Bose QC35II showed a very differently shaped curve in that range.
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Spoken like a true scientist.
A very refreshing post. Much appreciated.
I think a way of bypassing the difficult, long and costly part of that research could be to measure universally recognized balanced speakers (DSP corrected in the room) on a 5128.
Then use that measurement as a target curve for HP measurements.
Deriving the 5128 EQ correction curves for the same headphones you already have the GRAS ones for, and accounting for extra bass preference as your previous research already provided indications for.
From then on it should be a simple ABX round of however many people you want to test.
This should fast track the process quite a bit.
But it's still something that is precluded to the average DIY guy. It will be less effort, but still considerable effort.
D
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But if I understand you well, that would result int the same variation in bass response for all headphones ? Sean Olive provided in his presentation the individual measurements for the 20 headphones measured and there were quite a few significant variations in the variation
Headphones like the K550, DT770 pro, etc. showed a significant drop in response below 200-300Hz on the 5128, shaped in a way that's quite similar to seal deterioration, but other closed headphones (Bose, measured passively, for example), didn't exhibit a particularly strong change. Most open headphones such as the HD650, Utopia or HD800 showed a very moderate tilt below 1kHz, but the K701 showed a sharp drop as well.
I'm not certain that a single cause is at play here.
Could you elaborate on the bolded part ? By "highs", what range of frequencies do you mean ?
What I noticed is that in the 1-5kHz range some headphones such as the HD650 translated between the GRAS and 5128 fixtures with their FR curve shaped in a very similar way (you could normalise it at, let's say, 3kHz, and the two curves would mostly overlap), while others such as the Bose QC35II showed a very differently shaped curve in that range.
You're right. It's probably a number of causes that determine the difference in bass response.
I was just wandering if, other than the usual suspects like leakage differences, the FR response of the capsules had been taken into account.
For highs I intend the frequencies above which directivity plays a role in the measured FR and a lumped EQ is not applicable anymore. Broadly speaking, I think it should be around 2 kHz, if I remember some of the graphs I've seen in the past correctly.
1 kHz is probably still in the direction independent area, which I think (but don't quote me on this) can be corrected universally by EQ, at least under perfect seal conditions (which is like saying that practically speaking the distributed acoustic impedance behaviour could apply to most of the audio range, especially with HPs with poor sealing).
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