Diana: the second release by Abyss Headphones!
Jan 15, 2021 at 6:06 AM Post #3,362 of 3,891

MSA1133

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Wow, it's all about graph this and graph that. What happened to using your own ears?
 
Jan 15, 2021 at 6:25 AM Post #3,364 of 3,891

rthomas

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Wow, it's all about graph this and graph that. What happened to using your own ears?

Because

There are 10 million opinions on every headphone from random people on Headfi already

Because

Everybody's ears are shaped differently, everybody has varying levels of hearing ability/ hearing loss.

Because

What's the point of having a $50k measurement rig if you don't use it to compare headphones in a hobby that is based on comparing headphones?

Because

Abyss headphones cost $3000 to $5500. A massive amount of money. We want to know if they have significantly higher amounts of distortion than competing products.
 
Jan 15, 2021 at 7:30 AM Post #3,366 of 3,891

Merkurio

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I find Amir's arguments around the consistency of measurements completely valid, especially regarding the use of logarithmic scale vs the most common linear scale in the industry, which leads confusing perspective on Jude's part. I want to believe that he has done this without the intention of confusing people and benefiting Abyss, since from a personal acoustic engineer perspective, that scale is rarely used for these kind of measurements, both in the speaker and headphone industry.

On the other hand, I consider positive the conclusion of demanding products with good engineering for all of us, especially when we talk about four-digit gear.

Active feedback benefits both company and consumers, it's something we shouldn't forget (even if Abyss is a sponsor of this site).
 
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Jan 15, 2021 at 8:43 AM Post #3,367 of 3,891

MSA1133

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Because

There are 10 million opinions on every headphone from random people on Headfi already

Because

Everybody's ears are shaped differently, everybody has varying levels of hearing ability/ hearing loss.

Because

What's the point of having a $50k measurement rig if you don't use it to compare headphones in a hobby that is based on comparing headphones?

Because

Abyss headphones cost $3000 to $5500. A massive amount of money. We want to know if they have significantly higher amounts of distortion than competing products.

Simple. Just find a way to try them on yourself.

Edit: It's more fun this way :)
 
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Jan 15, 2021 at 8:49 AM Post #3,368 of 3,891

rthomas

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Simple. Just find a way to try them on yourself.

Sorry, I should clarify. I'm not just interested in the sound. For totl headphones I find the technical aspects interesting. I think others do as well. Otherwise there's no reason for a 20 min video from Jude about advancements in headphone measurements.

To quote a famous philosopher: " is expensive because it sound good"

Is not enough for me. I want Headfi to dig a little deeper :)

If that's not your thing, that's also perfectly understandable and valid.
 
Jan 15, 2021 at 9:30 AM Post #3,369 of 3,891

MSA1133

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Sorry, I should clarify. I'm not just interested in the sound. For totl headphones I find the technical aspects interesting. I think others do as well. Otherwise there's no reason for a 20 min video from Jude about advancements in headphone measurements.

To quote a famous philosopher: " is expensive because it sound good"

Is not enough for me. I want Headfi to dig a little deeper :)

If that's not your thing, that's also perfectly understandable and valid.

Yeah you're right I agree!

I tend to over simplify things and totally missed the interest in the technical aspects :L3000::thumbsup:
 
Jan 15, 2021 at 10:37 AM Post #3,370 of 3,891

HiFiGuy528

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A few members and Abyss Headphones pinged me to let me know about this discussion, asking me if we had measured the ABYSS DIANA V2. At the time we had not. I looked at the measurements at AudioScienceReview that I was being asked about, and thought what I saw (the measurements, the conclusions from those measurements, and the subsequent discussion there) interesting enough that we should measure it, too.

Let's start by looking at AudioScienceReview's DIANA V2 frequency response measurement:

ABYSS Diana V2 frequency response measurements.png
Fig.1 (above): AudioScienceReview's frequency response measurement of the ABYSS Headphones DIANA V2.

I agree with Amir at AudioScienceReview that this is an interesting, challenging headphone to measure. One look at the DIANA V2 (and its earpads) suggests that the way this headphone wears and couples is a little unconventional. We ran into another unconventional headphone recently (but unconventional in a different way than this one) when we measured the Apple AirPods Max. As with the AirPods Max, when you're dealing with an unusual headphone, you sometimes have to make some special considerations about how you go about measuring it -- the DIANA V2 is certainly one of those headphones.

I think I should start by making clear that while I can assure you there were different methods at work here (which I'll explain shortly), there is also the matter of the difference in our primary headphone measurement fixtures. AudioScienceReview used a GRAS 45CA (with GRAS RA0402 ear simulators) and we used the Brüel & Kjær 5128. We also have the same GRAS 45CA setup as AudioScienceReview and have measured with it for six years, so I am very familiar with it.

Whereas 711 simulators (like in the 45CA) were established 40 years ago primarily to measure things like hearing aids and telecom devices, the 5128 is a much more recent fixture (coming from 12 years of research and development) that was intended to measure everything from hearing aids to earphones to headphones like this, and of course many other things. Crucially, the Brüel & Kjær 5128 simulates human hearing from 20 Hz to 20 kHz, versus the 711's simulation range of only 100 Hz to 10 kHz.

Also important to note is that there's a reference plane on a 711 simulator where the device under test is intended to be positioned to ensure the input/transfer impedance is accurate [1]. (I'm referring to the input/transfer impedance of average human ear drums and the input/transfer impedance of an average human ear canal.) With a 711 simulator, moving away from the reference plane can result in a narrower simulation bandwidth than its specified 100 Hz to 10 kHz range. With the 5128, the average human impedance is equally well represented at any plane within it (and, again, from 20 Hz to 20 kHz) -- that is, there is no such measurement reference plane with it.

NOTE: If you're interested in learning more about the Brüel & Kjær 5128, please watch my presentation about the 5128 at the HBK (Hottinger Brüel & Kjær) Product Physics Conference. It's only 20 minutes long, but there is a lot of information in it that will help you understand some of the key developments and differences.

I'm unclear about some of the things I'm seeing in AudioScienceReview's measurement shown in Fig.1 above. The response > 5 kHz looks more like a rather random series of very narrow peaks/troughs that we might be able to eyeball an average through, but I think doing so might be a bit tortured.

In Fig.2 below, you can see the second of two of our measurement seatings of the DIANA V2 on the Brüel & Kjær 5128. While the level for the measurement in Fig.2 was set at 90 dBSPL @ 1 kHz and AudioScienceReview's was set at 94 dBSPL or 1 Pa at 425 Hz, for the sake of this comparison that level difference does not effect the shape of the frequency response.

Abyss-Headphones-Diana-V2---SEAT-02---FR---RAW---90-dBSPL-1-kHz.jpg
Fig.2 (above): ABYSS Headphones DIANA V2 frequency response as measured on the Brüel & Kjær 5128. (This is one of two seatings we had completed at the time of this post.)

Just as with AudioScienceReview's measurement in Fig.1, our measurement in Fig.2 is completely unsmoothed. You can see above 2 kHz there are substantial differences between our measurement and AudioScienceReview's measurement. I think it is very noteworthy in our measurement in Fig.2 that there is far less random hash > 5 kHz -- instead, there is a clear indication of an actual response. Again, the Brüel & Kjær 5128 simulates average adult human hearing from 20 Hz to 20 kHz, and the average human impedance is equally well represented at any measurement plane within the system.

In Fig.3 below, you can see the unsmoothed frequency responses from the two seatings we completed at the time of this post along with the smoothed average (1/12 octave) of these two seatings.

Abyss-Headphones-Diana-V2---SEAT-01-02---FR---90-dBSPL-1-kHz.jpg
Fig.3 (above): ABYSS Headphones DIANA V2 frequency response as measured on the Brüel & Kjær 5128, showing two seatings unsmoothed, and the average of those two seatings smoothed (1/12 octave).

Even with two separate seatings (representing two different headband sizing settings and in different positions), averaging through even the highest frequencies -- all the way to 20 kHz -- does not require the creativity that would be required averaging through that same range in the measurement in Fig.1.

Also noteworthy in comparing these measurements is the symmetry between channels in both seatings in Fig.3. Again, placement with this headphone is temperamental, but we can still achieve reasonable symmetry with it using a placement technique that I presented in a video on these forums and at the 2018 ALMA annual conference (AISE) that I have since refined.

Even then, additional care was required with the DIANA V2 as tiny movements over the fixture with this headphone could break seal and radically alter the bass response in one or both channels. It's also very sensitive to movement above 1 kHz, but the bass was the tougher issue for us with placement. For the DIANA V2, we actually used the aforementioned placement technique to line the channels up above 1 kHz, then switched between 20 Hz and 30 Hz sine stimuli and used very small adjustments to get those as close as we could to being within 1 dB of each other. Once we were able to do that, we ran the sweeps for that seating.

NOTE: While not every headphone is matched enough to measure symmetrically (left-right), we have found that premium headphones are more likely to. We always give the benefit of the doubt at the outset of measuring a given set of headphones, assuming that symmetry is possible, and our placement method generally works very well in helping us to determine that quickly.

Again, though, looking at the AudioScienceReview measurement in Fig.1 -- especially the lack of channel symmetry and the relative hash above 5 kHz -- I was curious about why this was happening, and thought maybe the DIANA V2 somehow interacted with 711 simulators poorly at higher frequencies. Since we have the same fixture as that used for the measurement in Fig.1 we decided to have a go at a couple of quick DIANA V2 seatings on it. Again, using real-time frequency response monitoring whilst placing the headphone on the GRAS 45CA fixture (and then micro-adjusting at 20 Hz and 30 Hz), we got the two seatings you'll see below in Fig.4 and Fig.5:

Abyss-Headphones-Diana-V2---SEAT-01-45CA---FR---90-dBSPL-1-kHz.jpg
Fig.4 (above): ABYSS Headphones DIANA V2 frequency response as measured on the GRAS 45CA (RA0401), seat 1.

Abyss-Headphones-Diana-V2---SEAT-02-45CA---FR---90-dBSPL-1-kHz.jpg
Fig.5 (above): ABYSS Headphones DIANA V2 frequency response as measured on the GRAS 45CA (RA0401), seat 2.

As you can see in Fig.4, it appears we may not have had a good seating, but at least it was reasonably symmetrical left-right. In Fig.5 we had a better seating, and it was still reasonably symmetrical. Of particular interest to me, though, was the response in both of these measurements > 5 kHz compared to the measurement in Fig.1. As you can see, in both measurements (Fig.4 and Fig.5), the response above 5 kHz had more symmetry and was less hashy than AudioScienceReview's measurement in Fig.1. Also, even though we might reject the measurement in Fig.4 before averaging, it's still more symmetrical throughout and there's certainly less hodgepodge in the treble range when compared to Fig.1.

After testing on our GRAS 45CA (identical in configuration to AudioScienceReview's), I suspect that the results we are seeing in the measurement in Fig.1 were likely due to issues of placement of the headphone on the measurement fixture.

When it comes to AudioScienceReview's total harmonic distortion (THD) measurements, we also had different results. In Fig.6 and Fig.7 below are AudioScienceReview's DIANA V2 THD measurements:

ABYSS Diana V2 Measurement distortion.png
Fig.6 (above): AudioScienceReview's total harmonic distortion (THD) measurement of the ABYSS Headphones DIANA V2 at 94 dBSPL, 104 dBSPL, and 114 dBSPL (425 Hz).

Our distortion measurements were lower at 94 dBSPL and 104 dBSPL, which I will show shortly. While choosing to show the Y-axis with a linear (versus logarithmic) scale is the judgment call of the measurer, I tend to prefer (and so use) a logarithmic Y-axis, as I find it easier to read and interpret. Again, that's a judgment call, and perhaps some prefer the linear Y-axis.

What puzzles me, though, is why AudioScienceReview is showing THD at 114 dBSPL. To put 114 decibels in perspective, I believe that's somewhere between the sound pressure level of a rock concert and an airplane taking off. 114 decibels is louder than some jackhammers. At 109 decibels, hearing impairment occurs after less than two minutes. I am unclear about why this level is being used to judge a headphone. In my opinion, looking to see how much distortion one gets from a headphone at 114 dBSPL is purely academic, and that's fine. However, I believe that should then be more of a sidebar item, not mixed in with more realistic, usable levels and then used to skew the appearance of a headphone's distortion characteristics.

So why was 114 decibels used? I think it was included for dramatic effect. After showing the measurement in Fig.6, AudioScienceReview's distortion assessment started with "Ouch!"

That THD measurement at 114 dBSPL was also used to create the conclusion that "Treble distortion shifts lower with increasing level" (see Fig.7 below). Is that a reasonable conclusion, though? I don't think so in this case. I'll get back to this shortly.

ABYSS Diana V2 Measurement distortion zoom out.png
Fig.7 (above): AudioScienceReview's total harmonic distortion (THD) measurement of the ABYSS Headphones DIANA V2 at 94 dBSPL, 104 dBSPL, and 114 dBSPL (425 Hz).


Below are our THD measurements of the DIANA V2:

Abyss-Headphones-Diana-V2---SEAT-01-02---THD---90-dBSPL-1-kHz.jpg
Fig.8 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz) as measured on the Brüel & Kjær 5128.

Abyss-Headphones-Diana-V2---SEAT-01-02---THD---94-dBSPL-425-Hz.jpg
Fig.9 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 94 dBSPL (425 Hz) as measured on the Brüel & Kjær 5128.

Abyss-Headphones-Diana-V2---SEAT-02---THD---104-dBSPL-425-Hz.jpg
Fig.10 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 104 dBSPL (425 Hz) as measured on the Brüel & Kjær 5128.

NOTE: We did not test at 114 dBSPL, as, in my opinion, there is simply no good reason to. The DIANA V2 is actually used by us at the Head-Fi office regularly, so I decided to keep the tests reasonable -- and useful...and fair.

At 94 dBSPL (425 Hz) and 104 dBSPL (425 Hz) -- which are two of the three levels measured by AudioScienceReview -- our measured THD was lower. At 94 dBSL, AudioScienceReview's measured THD at 20 Hz was < 3% (Fig.7), and we measured < 1% at 20 Hz (Fig.9). At 104 dBSPL, AudioScienceReview's measured THD at 20 Hz (Fig.7) was around 8%, and we measured > 3% (Fig.10).

NOTE: On the GRAS 45CA (RA0401) we measured at both 90 dBSPL (1 kHz) and 94 dBSPL (425 Hz), and the measured THD levels at 20 Hz were nearly identical to our Brüel & Kjær 5128 measurements (but there were slight differences through the midrange and treble).

I suspect our measured THD may be lower than AudioScienceReview's for a couple of reasons: First, we use a Herzan acoustic and vibration isolation enclosure. Given the physics involved, our Herzan enclosure is not entirely effective at lower frequencies, but it does help. Second, our measured frequency response had quite a bit more energy approaching 20 Hz. At a level of 94 dBSPL (425 Hz), both the left and right channels were at around 87.5 dBSPL at 20 Hz in our measurements, which is around 10 dBSPL higher than one of the channels in AudioScienceReview's measurement in Fig.1 and around 5 dBSPL higher than the other. Since both AudioScienceReview and we are expressing THD as a ratio, this should lead to a lower measured percentage in our measurement given our higher measured output there.

As for AudioScienceReview's conclusion that "Treble distortion shifts lower with increasing level," we have come to a different conclusion. We measured 104 dBSPL on only one of the two seatings, so isolating the THD for that seating at 90 dBSPL (1 kHz), 94 dBSPL (425 Hz), and 104 dBSPL (425 Hz), we measured the THD in Fig.11 below:

Abyss-Headphones-Diana-V2---SEAT-02---AVG-THD---90-dBSPL-1-kHz---94-dBSPL-425-Hz---104-dBSPL-4...jpg
Fig.11 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz), 94 dBSPL (425 Hz), and 104 dBSPL (425 Hz) as measured on the Brüel & Kjær 5128.

As you can see in Fig.11, from 90 dBSPL to 104 dBSPL, treble distortion does not shift lower with increasing level.

At some point in the future we will likely add two or three more measurement seatings to better round out our DIANA V2 measurements.

We've been measuring headphones for six years at Head-Fi HQ, having performed thousands of them over that time. Just today, we were at Head Acoustics' US headquarters for the third social-distanced day of measuring ANC headphones in the past couple of months. We discuss headphone measurements with headphone engineers and product teams almost daily, routinely sharing and discussing our results. At any given time at Head-Fi HQ, we have a number of prototypes and pre-production headphones that we are asked to both measure and evaluate subjectively. And still, six years later, we still feel like headphone measurement newbies here every time a headphone like the Apple AirPods Max or ABYSS DIANA V2 challenges our measurement routines.

I have not looked at all of AudioScienceReview's headphone measurements, but certainly with this one I think AudioScienceReview should consider re-measuring it and working on better and more careful placement of the headphone on their measurement fixture. Again, we would like to improve our DIANA V2 measurements by adding a two or three more seatings ourselves. I do strongly agree, though, that the ABYSS Headphones DIANA V2 is more challenging than most headphones to measure.



Unless otherwise noted, the measurements in this post were made with:



References:

1. Johansen B, Jønsson S, inventors; Brüel & Kjær Sound & Vibration Measurement A/S, assignee. Human like ear simulator. United States Patent Application US 2015/0124978 A1. United States Patent and Trademark Office. 7 May 2015.

Real science done correctly. Thank YOU!
 
Jan 15, 2021 at 10:56 AM Post #3,371 of 3,891

TheMiddleSky

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When people start to determine sound quality of headphones on human ears by curious about distortion number... indeed make me worried about what would happen how manufacture would moved to create products that please nerd of graph, not us, the audiophile who enjoy the actual experience of listening.

Audio is not about who create the highest/lowest number. Everything is all about golden ratio of many many many factors together.

Thanks for all effort and time for @jude to do the comprehensive measurement though!
 
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Jan 15, 2021 at 11:45 AM Post #3,372 of 3,891

sherm137

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A few members and Abyss Headphones pinged me to let me know about this discussion, asking me if we had measured the ABYSS DIANA V2. At the time we had not. I looked at the measurements at AudioScienceReview that I was being asked about, and thought what I saw (the measurements, the conclusions from those measurements, and the subsequent discussion there) interesting enough that we should measure it, too.

Let's start by looking at AudioScienceReview's DIANA V2 frequency response measurement:

ABYSS Diana V2 frequency response measurements.png
Fig.1 (above): AudioScienceReview's frequency response measurement of the ABYSS Headphones DIANA V2.

I agree with Amir at AudioScienceReview that this is an interesting, challenging headphone to measure. One look at the DIANA V2 (and its earpads) suggests that the way this headphone wears and couples is a little unconventional. We ran into another unconventional headphone recently (but unconventional in a different way than this one) when we measured the Apple AirPods Max. As with the AirPods Max, when you're dealing with an unusual headphone, you sometimes have to make some special considerations about how you go about measuring it -- the DIANA V2 is certainly one of those headphones.

I think I should start by making clear that while I can assure you there were different methods at work here (which I'll explain shortly), there is also the matter of the difference in our primary headphone measurement fixtures. AudioScienceReview used a GRAS 45CA (with GRAS RA0402 ear simulators) and we used the Brüel & Kjær 5128. We also have the same GRAS 45CA setup as AudioScienceReview and have measured with it for six years, so I am very familiar with it.

Whereas 711 simulators (like in the 45CA) were established 40 years ago primarily to measure things like hearing aids and telecom devices, the 5128 is a much more recent fixture (coming from 12 years of research and development) that was intended to measure everything from hearing aids to earphones to headphones like this, and of course many other things. Crucially, the Brüel & Kjær 5128 simulates human hearing from 20 Hz to 20 kHz, versus the 711's simulation range of only 100 Hz to 10 kHz.

Also important to note is that there's a reference plane on a 711 simulator where the device under test is intended to be positioned to ensure the input/transfer impedance is accurate [1]. (I'm referring to the input/transfer impedance of average human ear drums and the input/transfer impedance of an average human ear canal.) With a 711 simulator, moving away from the reference plane can result in a narrower simulation bandwidth than its specified 100 Hz to 10 kHz range. With the 5128, the average human impedance is equally well represented at any plane within it (and, again, from 20 Hz to 20 kHz) -- that is, there is no such measurement reference plane with it.

NOTE: If you're interested in learning more about the Brüel & Kjær 5128, please watch my presentation about the 5128 at the HBK (Hottinger Brüel & Kjær) Product Physics Conference. It's only 20 minutes long, but there is a lot of information in it that will help you understand some of the key developments and differences.

I'm unclear about some of the things I'm seeing in AudioScienceReview's measurement shown in Fig.1 above. The response > 5 kHz looks more like a rather random series of very narrow peaks/troughs that we might be able to eyeball an average through, but I think doing so might be a bit tortured.

In Fig.2 below, you can see the second of two of our measurement seatings of the DIANA V2 on the Brüel & Kjær 5128. While the level for the measurement in Fig.2 was set at 90 dBSPL @ 1 kHz and AudioScienceReview's was set at 94 dBSPL or 1 Pa at 425 Hz, for the sake of this comparison that level difference does not effect the shape of the frequency response.

Abyss-Headphones-Diana-V2---SEAT-02---FR---RAW---90-dBSPL-1-kHz.jpg
Fig.2 (above): ABYSS Headphones DIANA V2 frequency response as measured on the Brüel & Kjær 5128. (This is one of two seatings we had completed at the time of this post.)

Just as with AudioScienceReview's measurement in Fig.1, our measurement in Fig.2 is completely unsmoothed. You can see above 2 kHz there are substantial differences between our measurement and AudioScienceReview's measurement. I think it is very noteworthy in our measurement in Fig.2 that there is far less random hash > 5 kHz -- instead, there is a clear indication of an actual response. Again, the Brüel & Kjær 5128 simulates average adult human hearing from 20 Hz to 20 kHz, and the average human impedance is equally well represented at any measurement plane within the system.

In Fig.3 below, you can see the unsmoothed frequency responses from the two seatings we completed at the time of this post along with the smoothed average (1/12 octave) of these two seatings.

Abyss-Headphones-Diana-V2---SEAT-01-02---FR---90-dBSPL-1-kHz.jpg
Fig.3 (above): ABYSS Headphones DIANA V2 frequency response as measured on the Brüel & Kjær 5128, showing two seatings unsmoothed, and the average of those two seatings smoothed (1/12 octave).

Even with two separate seatings (representing two different headband sizing settings and in different positions), averaging through even the highest frequencies -- all the way to 20 kHz -- does not require the creativity that would be required averaging through that same range in the measurement in Fig.1.

Also noteworthy in comparing these measurements is the symmetry between channels in both seatings in Fig.3. Again, placement with this headphone is temperamental, but we can still achieve reasonable symmetry with it using a placement technique that I presented in a video on these forums and at the 2018 ALMA annual conference (AISE) that I have since refined.

Even then, additional care was required with the DIANA V2 as tiny movements over the fixture with this headphone could break seal and radically alter the bass response in one or both channels. It's also very sensitive to movement above 1 kHz, but the bass was the tougher issue for us with placement. For the DIANA V2, we actually used the aforementioned placement technique to line the channels up above 1 kHz, then switched between 20 Hz and 30 Hz sine stimuli and used very small adjustments to get those as close as we could to being within 1 dB of each other. Once we were able to do that, we ran the sweeps for that seating.

NOTE: While not every headphone is matched enough to measure symmetrically (left-right), we have found that premium headphones are more likely to. We always give the benefit of the doubt at the outset of measuring a given set of headphones, assuming that symmetry is possible, and our placement method generally works very well in helping us to determine that quickly.

Again, though, looking at the AudioScienceReview measurement in Fig.1 -- especially the lack of channel symmetry and the relative hash above 5 kHz -- I was curious about why this was happening, and thought maybe the DIANA V2 somehow interacted with 711 simulators poorly at higher frequencies. Since we have the same fixture as that used for the measurement in Fig.1 we decided to have a go at a couple of quick DIANA V2 seatings on it. Again, using real-time frequency response monitoring whilst placing the headphone on the GRAS 45CA fixture (and then micro-adjusting at 20 Hz and 30 Hz), we got the two seatings you'll see below in Fig.4 and Fig.5:

Abyss-Headphones-Diana-V2---SEAT-01-45CA---FR---90-dBSPL-1-kHz.jpg
Fig.4 (above): ABYSS Headphones DIANA V2 frequency response as measured on the GRAS 45CA (RA0401), seat 1.

Abyss-Headphones-Diana-V2---SEAT-02-45CA---FR---90-dBSPL-1-kHz.jpg
Fig.5 (above): ABYSS Headphones DIANA V2 frequency response as measured on the GRAS 45CA (RA0401), seat 2.

As you can see in Fig.4, it appears we may not have had a good seating, but at least it was reasonably symmetrical left-right. In Fig.5 we had a better seating, and it was still reasonably symmetrical. Of particular interest to me, though, was the response in both of these measurements > 5 kHz compared to the measurement in Fig.1. As you can see, in both measurements (Fig.4 and Fig.5), the response above 5 kHz had more symmetry and was less hashy than AudioScienceReview's measurement in Fig.1. Also, even though we might reject the measurement in Fig.4 before averaging, it's still more symmetrical throughout and there's certainly less hodgepodge in the treble range when compared to Fig.1.

After testing on our GRAS 45CA (identical in configuration to AudioScienceReview's), I suspect that the results we are seeing in the measurement in Fig.1 were likely due to issues of placement of the headphone on the measurement fixture.

When it comes to AudioScienceReview's total harmonic distortion (THD) measurements, we also had different results. In Fig.6 and Fig.7 below are AudioScienceReview's DIANA V2 THD measurements:

ABYSS Diana V2 Measurement distortion.png
Fig.6 (above): AudioScienceReview's total harmonic distortion (THD) measurement of the ABYSS Headphones DIANA V2 at 94 dBSPL, 104 dBSPL, and 114 dBSPL (425 Hz).

Our distortion measurements were lower at 94 dBSPL and 104 dBSPL, which I will show shortly. While choosing to show the Y-axis with a linear (versus logarithmic) scale is the judgment call of the measurer, I tend to prefer (and so use) a logarithmic Y-axis, as I find it easier to read and interpret. Again, that's a judgment call, and perhaps some prefer the linear Y-axis.

What puzzles me, though, is why AudioScienceReview is showing THD at 114 dBSPL. To put 114 decibels in perspective, I believe that's somewhere between the sound pressure level of a rock concert and an airplane taking off. 114 decibels is louder than some jackhammers. At 109 decibels, hearing impairment occurs after less than two minutes. I am unclear about why this level is being used to judge a headphone. In my opinion, looking to see how much distortion one gets from a headphone at 114 dBSPL is purely academic, and that's fine. However, I believe that should then be more of a sidebar item, not mixed in with more realistic, usable levels and then used to skew the appearance of a headphone's distortion characteristics.

So why was 114 decibels used? I think it was included for dramatic effect. After showing the measurement in Fig.6, AudioScienceReview's distortion assessment started with "Ouch!"

That THD measurement at 114 dBSPL was also used to create the conclusion that "Treble distortion shifts lower with increasing level" (see Fig.7 below). Is that a reasonable conclusion, though? I don't think so in this case. I'll get back to this shortly.

ABYSS Diana V2 Measurement distortion zoom out.png
Fig.7 (above): AudioScienceReview's total harmonic distortion (THD) measurement of the ABYSS Headphones DIANA V2 at 94 dBSPL, 104 dBSPL, and 114 dBSPL (425 Hz).


Below are our THD measurements of the DIANA V2:

Abyss-Headphones-Diana-V2---SEAT-01-02---THD---90-dBSPL-1-kHz.jpg
Fig.8 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz) as measured on the Brüel & Kjær 5128.

Abyss-Headphones-Diana-V2---SEAT-01-02---THD---94-dBSPL-425-Hz.jpg
Fig.9 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 94 dBSPL (425 Hz) as measured on the Brüel & Kjær 5128.

Abyss-Headphones-Diana-V2---SEAT-02---THD---104-dBSPL-425-Hz.jpg
Fig.10 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 104 dBSPL (425 Hz) as measured on the Brüel & Kjær 5128.

NOTE: We did not test at 114 dBSPL, as, in my opinion, there is simply no good reason to. The DIANA V2 is actually used by us at the Head-Fi office regularly, so I decided to keep the tests reasonable -- and useful...and fair.

At 94 dBSPL (425 Hz) and 104 dBSPL (425 Hz) -- which are two of the three levels measured by AudioScienceReview -- our measured THD was lower. At 94 dBSL, AudioScienceReview's measured THD at 20 Hz was < 3% (Fig.7), and we measured < 1% at 20 Hz (Fig.9). At 104 dBSPL, AudioScienceReview's measured THD at 20 Hz (Fig.7) was around 8%, and we measured > 3% (Fig.10).

NOTE: On the GRAS 45CA (RA0401) we measured at both 90 dBSPL (1 kHz) and 94 dBSPL (425 Hz), and the measured THD levels at 20 Hz were nearly identical to our Brüel & Kjær 5128 measurements (but there were slight differences through the midrange and treble).

I suspect our measured THD may be lower than AudioScienceReview's for a couple of reasons: First, we use a Herzan acoustic and vibration isolation enclosure. Given the physics involved, our Herzan enclosure is not entirely effective at lower frequencies, but it does help. Second, our measured frequency response had quite a bit more energy approaching 20 Hz. At a level of 94 dBSPL (425 Hz), both the left and right channels were at around 87.5 dBSPL at 20 Hz in our measurements, which is around 10 dBSPL higher than one of the channels in AudioScienceReview's measurement in Fig.1 and around 5 dBSPL higher than the other. Since both AudioScienceReview and we are expressing THD as a ratio, this should lead to a lower measured percentage in our measurement given our higher measured output there.

As for AudioScienceReview's conclusion that "Treble distortion shifts lower with increasing level," we have come to a different conclusion. We measured 104 dBSPL on only one of the two seatings, so isolating the THD for that seating at 90 dBSPL (1 kHz), 94 dBSPL (425 Hz), and 104 dBSPL (425 Hz), we measured the THD in Fig.11 below:

Abyss-Headphones-Diana-V2---SEAT-02---AVG-THD---90-dBSPL-1-kHz---94-dBSPL-425-Hz---104-dBSPL-4...jpg
Fig.11 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz), 94 dBSPL (425 Hz), and 104 dBSPL (425 Hz) as measured on the Brüel & Kjær 5128.

As you can see in Fig.11, from 90 dBSPL to 104 dBSPL, treble distortion does not shift lower with increasing level.

At some point in the future we will likely add two or three more measurement seatings to better round out our DIANA V2 measurements.

We've been measuring headphones for six years at Head-Fi HQ, having performed thousands of them over that time. Just today, we were at Head Acoustics' US headquarters for the third social-distanced day of measuring ANC headphones in the past couple of months. We discuss headphone measurements with headphone engineers and product teams almost daily, routinely sharing and discussing our results. At any given time at Head-Fi HQ, we have a number of prototypes and pre-production headphones that we are asked to both measure and evaluate subjectively. And still, six years later, we still feel like headphone measurement newbies here every time a headphone like the Apple AirPods Max or ABYSS DIANA V2 challenges our measurement routines.

I have not looked at all of AudioScienceReview's headphone measurements, but certainly with this one I think AudioScienceReview should consider re-measuring it and working on better and more careful placement of the headphone on their measurement fixture. Again, we would like to improve our DIANA V2 measurements by adding a two or three more seatings ourselves. I do strongly agree, though, that the ABYSS Headphones DIANA V2 is more challenging than most headphones to measure.



Unless otherwise noted, the measurements in this post were made with:



References:

1. Johansen B, Jønsson S, inventors; Brüel & Kjær Sound & Vibration Measurement A/S, assignee. Human like ear simulator. United States Patent Application US 2015/0124978 A1. United States Patent and Trademark Office. 7 May 2015.
I appreciate the measurements here, but they aren't the THD aren't a direct comparison to ASR's. We need to see the THD measured on your GRAS. It would be really helpful.
Also, when verifying a manufacturers headphone, it would be helpful to disclose whether that manufacturer is a sponsor of HeadFi or not. I believe Abyss does sponsor HeadFi.

Real science done correctly. Thank YOU!
Then why didn't he share the THD measurements of the GRAS to make a direct comparison to ASR? Measuring on a different rig and then making a conclusion based on someone else's measurements is NOT real science. You just introduced a new HUGE variable.
 
Jan 15, 2021 at 11:47 AM Post #3,373 of 3,891

bobbooo

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NOTE: On the GRAS 45CA (RA0401) we measured at both 90 dBSPL (1 kHz) and 94 dBSPL (425 Hz), and the measured THD levels at 20 Hz were nearly identical to our Brüel & Kjær 5128 measurements (but there were slight differences through the midrange and treble).

Thanks for all these measurements and the detailed write-up. Could you post the GRAS 45CA distortion measurements at 94 dBSPL (425 Hz) for completeness and to allow for a direct like-for-like comparison with ASR's distortion measurements?
 
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Jan 15, 2021 at 12:41 PM Post #3,375 of 3,891

Well this certainly escalated overnight.

amirm said:
Notice the issues on the graph. First, he measures frequency response using 45CA but doesn't post the distortion. Why? He says this:

"NOTE: On the GRAS 45CA (RA0401) we measured at both 90 dBSPL (1 kHz) and 94 dBSPL (425 Hz), and the measured THD levels at 20 Hz were nearly identical to our Brüel & Kjær 5128 measurements (but there were slight differences through the midrange and treble). "

Oh? Why not let us see it?

amirm said:
As I just post, he did NOT post distortion measurements using the GRAS but instead chose to use B&K. Why? He had the data. Why didn't he post it when it could be a more proper comparison?

He has a knack for making just about anything seem insidious. My main point in showing the GRAS measurements was to show that a better seating on the same fixture he uses is possible with that headphone. Not including the THD measurements from the better of our two GRAS seatings (Fig.5 in my previous post)) was not a Machiavellian oversight. It was because my main point in bringing the GRAS 45CA in was to discuss the seating upon it. And, as I mentioned, the THD with was rather similar with it anyway (compared to the 5128). Here they are, at 90 dBSPL (1 kHz) compared to the 5128, and 94 dBSPL (425 Hz) also compared to the 5128:

Abyss-Headphones-Diana-V2---THD---90-dBSPL-1-kHz---5128-and-45CA.jpg

Fig.12 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz) as measured on the GRAS 45 CA (one seat) and Brüel & Kjær 5128 (two seats).

Abyss-Headphones-Diana-V2---THD---94-dBSPL-425-Hz---5128-and-45CA.jpg

Fig.12 (above): ABYSS Headphones DIANA V2 total harmonic distortion (THD) at 90 dBSPL (1 kHz) as measured on the GRAS 45 CA (one seat) and Brüel & Kjær 5128 (two seats).

Again, the main point in bringing the GRAS 45CA into my previous post was to discuss seating. Looking at his frequency response measurement in Fig.1 of my previous post, I think it's reasonable to question the seating. It seems Amir disagrees. and he even suggested that I must have resorted to using bungies to do it:

amirm said:
As to frequency response, yes he used GRAS but so what? As I said, I can also put bungie cords on the headphones and get tons more bass. That doesn't tell you anything useful.

We did not use bungies, rubber bands, or any other artificial means to secure the headphone to either of the fixtures in any of these measurements. Again, that's one of my main points: He should consider revisiting his placement, especially considering the frequency response he measured, both in the bass and treble.

Rather than even consider the possibility that he could get better placement in light of what's been shown, he'd rather suggest that we had to artificially tension it. Again, we did not artificially tension the headphone in any way. If we did, I think you'd see a much flatter measurement in the low bass.

amirm said:
Second, the moment your frequency response changes, your ratios change for the same distortion. So you can't make THD Percentage comparisons. He should have post absolute distortion as I have.

While Amir did include a THD level measurement, it was not really the featured THD measurement, nor was it the one at the crux of his key THD criticisms. Once again, while he's now suggesting my use of THD as a ratio (a percentage) is some kind of trickery, he's basing most of his THD-related conclusions (both in his annotations and in his post) on his THD ratio measurements seen in Fig.6 and Fig.7 of my previous post.

Also, while there are valid arguments to be made for using THD level more on balance, Amir and I are not alone in currently using THD expressed as a ratio as our primary THD measurements -- most everyone else does, too.

amirm said:
He also makes a mess of the comparison by using his scale with log which of course compressed the heck out of the graph vs linear one I use (same as what Klippel uses for speaker measurements).

Again, while choosing to show the Y-axis with a linear (versus logarithmic) scale is his judgment call (and I do not recall criticizing that), I tend to prefer (and so use) a logarithmic Y-axis, as I find it easier to read and interpret. Again, that's a judgment call, and perhaps some prefer the linear Y-axis. From what I can tell, most in our space use log scale when showing THD ratio.

Other than perhaps lowering bass distortion (THD%) by improving his placement, the other key point I made was regarding his use of THD at 114 dBSPL. Again, while I think that's a reasonable thing to look at as an academic exercise, it's a level I will not drive most of the headphones here to -- a level that can cause hearing loss in under two minutes. No doubt some headphones will do better than others driven to those levels. Again, from 90 dB to 104 dB, though, the treble distortion did expectedly increase but it did not shift with the DIANA V2.

Going back to the seating discussion: Amir stated that he verified his measurement with his own ears and equalization. While I respect that he trusts that method as validation of a measurement or seating well done (and suggests that we should trust it, too), I'm not as confident. I still think he should (and will) find ways to improve his seating -- yes, without the need for bungies or other mechanical assistance he'd have you believe we used. After six years, we're still finding ways to improve our methods. I think our method of doing real-time approximations of frequency response as we place the headphones an important step for us.

Last week, I did something similar when someone brought RTINGS' measurement of the AirPods Max to my attention and asked me to post about it. (At the time of my post, I did not know that the measurement I was looking at was by RTINGS.) Again, in that instance it was a discussion of placement, which I posted about with supporting measurements. (I was able to recreate on the 5128 most of what they were getting on their Head Acoustics manikin.) You can see that post by clicking here. I haven't heard from RTINGS yet and don't expect to. If they do contact me, I hope it's more productive (and more civil) than this.
 
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