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Oppo PM-1: A New Planar Magnetic Headphone! - Page 153

post #2281 of 2545

Whatcha doing on these boards? Go back and listen. I'm still trapped at work so at least I have an excuse.

post #2282 of 2545
Quote:
Originally Posted by bigshot View Post

 

I hear up to about 16-17kHz which is beyond the point the PM-1s start rolling off.

 

Now that you have asked that, may I ask what you did when you were comparing the headphones with your friends to eliminate the effect of expectation bias? Did you each listen and then reveal what you heard separately, or did one of you tell the others what he thought before they had even listened?

 

I've never had any experience with the headphones in the past and no one told me which was which. I didn't really look and, at least on head, the PM1 and PM2 felt the same. I brought my own music and we used the same upstream gear (USB drive (NAND flash) > BDP105 > HA-1). The recordings I used I'm very familiar with:

 

  • MTT/SFS performing Mahler's 1st (from my original SACD, ripped to ISO using a PS3 and converted to DFF files)
    • I attended the performance on Sept 19, 2001 and actually horse traded to get a ticket to another performance that weekend on a different series subscription (difficult because I was at University 2 hours away and had little to no disposable income, but I lived without eating for a few days). Absolutely stunning to have experienced twice and my favorite rendition of probably my favorite symphonic poem.
    • I'm intimately familiar with the venue (Davies Symphony Hall) and the rough seating area this recording was mastered to represent. Unlike a lot of classical masters, your position doesn't seem to move around AND you never feel like you're sitting in the middle of the orchestra.
    • The fine details present and subtle volume changes are very difficult for a lot of headphones to reproduce clearly at lower volume levels.
    • There is quite a bit of audience and ambient noise in the recording. These cues are really useful in telling how well headphones both present these tiny details, but also how well the sounds are presented spatially (I can localize the sounds quite well on a great loudspeaker setup and reasonably well on a very good headphone setup).
  • Jean-Guihen Queyras' Bach Cello Suites recording (CD ripped via EAC to regular ol' 16/44 FLAC) 
    • Amazingly well handled openings to EVERY SUITE, the way he scales dynamics while maintaining very tight control is pretty damn masterful and shows how well any particular amp/headphone combo handles dynamic swings.
    • Lots of layered string resonances and harmonics! The natural frequencies at which his cello resonates are incredibly beautiful. I've always meant to track down what instrument he was playing. I've found most headphones that are not the HD800 have difficulty capturing ALL of the resonances and harmonics in this piece. 

 

Having no familiarity with the Oppo line until my listening session at the meet, I performed my listening tests and noted my impressions of each unit BEFORE I was told for certain which was which. Yes, this wasn't the most rigorous of testing methodologies, but I did hear a noticeable difference with the PM1 that had the new pads (PM1 with <PM2 tuned> pads) on all the tracks I listened to.

post #2283 of 2545
Quote:
Originally Posted by purrin View Post
 

Not bad, but not as reliable as from a dedicated headphone measuring setup which I would have preferred seeing.

 

There are a few of those online now. Look em up! They aren't too different from mine.

 

Quote:
Originally Posted by Eric_C View Post
 

EQing is the same as taking measurements? And by ear?

 

EQing of speaker rigs is often done by ear. Automatic calibration using microphones and pink noise rarely works correctly. It just gives you a starting point.

 

Quote:
Originally Posted by hans030390 View Post
 

I'm glad you're happy with the PM-1, but they are certainly not neutral. I still quite liked them despite of this. Nothing wrong with that. Lots of measurements to back up their relative sound, which is mostly just a bit too rolled up top

 

What imbalances do you see (frequency range and dB)?

 

The roll off on the Oppos is in the top octave of human hearing where we stop being able to discern pitch and it just becomes a high pitched noise. I am much more impressed with a flat response below 14kHz than I am above that. Most people discern that last octave differently, so a precise balance isn't as important as the core frequencies.

 

The Oppos are STONE FLAT from the lowest bass up to the upper midrange. That is a remarkable achievement as far as I'm concerned. That is the meat of music right there.

 

Quote:
Originally Posted by Infoseeker View Post
 

I don't know about open-backed headphones. However, on closed-back headphones, the seal acquired by the material used is very significant on the sound of the headphones. Especially a factor in terms of air available for the drivers.

 

I am talking about the Oppo PM-1 pads. Other people are trying to extend that into every kind of headphone made. Do I think stuffing a sock in each cup or holding the cans two inches further away from each ear won't affect the sound? Of course not. Do I think it's silly to attribute a significant frequency response difference between PM-1s and PM-2s to the use of pleather instead of leather? Yes, I think that is absurd.

 

Quote:
Originally Posted by nicdub View Post
 

From the Oppo website, regarding the pad changes:

 

I just took my PM-1s and used my reference recording with one pad on and the other pad completely off. You would think it would alter the sound significantly, but it didn't. It boosted the upper midrange a tiny bit (Fletcher Munson) and altered the volume overall a hair because the driver was closer to the ear, but it didn't change the treble or overall sound of the response much at alll. Try it yourself. Easy test.

 

Quote:
Originally Posted by hans030390 View Post
 

Yeah, they have a pretty gradual roll-off starting around 1KHz. From my measurements, which I can't post here, it's around -5dB at 10KHz (slight peak, actually, as the downward slope from 1KHz dips around 8KHz) and then drops off like a rock after that.

 

I think you have a typo in there. The curve goes up and down between 6kHz and 10kHz. Some in the plus range, some below. I charted a big boost at 6kHz and a narrow dip right after that, then it came back to flat before starting to roll off above 12. That is what I've seen in other measurements too, but they saw the boost at 8. Maybe you are averaging stuff out too much. Above 14kHz, I really don't worry. That last octave gets less and less important as you go up.

 

Quote:
Originally Posted by PerfectHiFi View Post

Did you check your measuring microphone's FR? If Oppo specifies up to 50 kHz FR for the PM-x, I do believe that these drivers can't roll-off like a rock...

 

The specs for extension don't indicate a +/- dB range. They may emit some kind of sound up to 50kHz, but it isn't at the same volume as the core frequencies. The main range that really matters is from 30Hz to 10kHz. If you can get in the ballpark beyond that, it's icing on the cake. Transducers will never be perfect at the extreme ends. They're designed to nail the middle.

 

Quote:
Originally Posted by purrin View Post
 

A lot of people rely on forums such as this to make purchasing decisions. They rely on subjective impressions, which can be contradictory or inconsistent, or they can also rely on measurements within the same framework - comparing A to say a known B - as an additional data point.

 

There is a third measurement that is extremely important to put the other measurements into perspective. The specs for normal human hearing. If you don't take that into account, you can end up going down a rabbit hole of theory instead of the horse sense of what you can actually hear.

 

Quote:
Originally Posted by zerodeefex View Post
 

 I did hear a noticeable difference with the PM1 that had the new pads (PM1 with <PM2 tuned> pads) on all the tracks I listened to.

 

I don't know anything about that particular pad. But I know the PM-1 leather pad and velour pad were virtually identical in sound quality, and the PM-1s with both of those were remarkably flat through the most important frequency range. If these new pads sound significantly different, especially from the bottom up to around 5kHz, I don't think that is necessarily a good thing. You can't be more flat that flat. If the top of the treble is flatter, OK, but that is basically icing on the cake.


Edited by bigshot - 8/6/14 at 10:28pm
post #2284 of 2545
post #2285 of 2545

Bigshot, I do want to reiterate that I actually really liked the PM-1. It did some things poorly that made it worth far from its retail price (HD600 does less wrong at around $300, so I'd pay maybe $300 for the PM-1, only since it looks and feels so nice...plus dat box...), but it also hit a lot of sweet spots that fit my tastes perfectly. I am fully aware my tastes don't match up with perfectly neutral all the time, and that's OK with me. In the end, I just couldn't justify the price.

 

I have posted a fairly detailed analysis/review, including measurements, of the PM-1 in a different corner of the internet, which is where I tend to exclusively post most of my things these days. You might see some stuff from me on HF here and there. I've verified you can easily find my posted information via a quick Google search, but I can't talk about it much other than that. You'll also be able to find details on how I do my measurements at this location, though, to be brief, BMF in these forums helped me out with hardware and the overall measurement setup/method. That should give you some clues.

 

Let me give you a sneak peak at one part of my measurements (another hint, I do very little averaging...1/24 octave...measurements are captured using multiple runs and then averaging those...raw data available at said secret location):

 

 

So, no typos on my part, and you'll have to look elsewhere to get info beyond this teaser. As you can see, they have a fairly good balance, tilted towards a warm (not bassy) sound signature. Don't worry about the slight tilt towards extra bass, as the PM-1 really isn't a bassy headphone, as mentioned, and relatively neutral headphones like the HD600 aren't perfectly flat down their either. Treble is definitely rolled off, but I liked how laid-back and easy to listen to they were. I could ideally use a bit more detail and resolution, though. I agree that the drop off above 10-12KHz isn't too important, though I know some think otherwise. I do think this partially accounts for their lack of air, as they sound rather closed (very, very narrow soundstage, seems to wrap directly around your head in a weird fashion).

 

Frequency response isn't everything, though. These do have a bit of a distortion bump in the low mids/upper bass, which might contribute further to their warm sound. But, overall THD levels are great, so I wasn't worried about that. They do quite well with resonance and ringing, so I don't know why people keep perpetuating this claim that they have a slow decay (I think this stemmed from a crappy set of measurements a while back?). They don't have slow decay, especially not up top. But, overall, the PM-1 simply sounded over-damped and constricted. I used a particular term for it originally that mods will edit out here, but it just sounded a bit dead and lifeless, and lacked power, to me (too laid-back across the spectrum, really).

 

While measurements of the PM-1 do show some noticeable variations from system to system (to be expected), I've not yet seen anything that validates some of your claims (especially that supposed bump around 6KHz, though I suppose it could be product variation, particularly sensitive or broken hearing, etc...lots of possibilities). Do you have hard sources for your claims? What other measurements have you seen? Genuinely curious.

 

Needless to say, I'm very encouraged about the PM-2 and the new pads they're using. The PM-1 was almost there to my ears, and I'd love to get my hands on a PM-2 and those new pads for a full analysis (maybe Oppo will throw me a bone if I'm lucky :wink_face:). They sound like they might literally be exactly what I'm looking for in a headphone.


Edited by hans030390 - 8/8/14 at 1:42am
post #2286 of 2545
Quote:
Originally Posted by hans030390 View Post
 

Let me give you a sneak peak at one part of my measurements (another hint, I do very little averaging...1/24 octave...measurements are captured using multiple runs and then averaging those...raw data available at said secret location):

 

 

That is a damn fine looking curve. Even better than the one I got. If something can hew close to +/- 3dB of flat with no narrow peaks out to the point where the ear can't discern pitch any more, I am happy with it. Remember, there is sample variation from one pair of cans to the next. They can't manufacture them to absolute spec. But every measurement I've seen shows pretty much the same thing you have there. Nice job of measuring!

 

By the way, the Q width on that distortion in the lower midrange is SUPER narrow and it's right below the threshold of audibility. No one would be able to hear that in the real world. And I believe Tyll's measurements showed the bump I measured at 8kHz instead of 6. You seem to have it at 10. Still and all, the bump was in the 3dB range and the dip after it was very narrow. All unlikely to affect the overall sound when listening to music.


Edited by bigshot - 8/8/14 at 10:58am
post #2287 of 2545

It's a pretty good curve, I agree. In particular, I like how linear and smooth it is, despite the warm/dark tilt. In this case, frequency response isn't everything. It's often hard to measure characteristics like a headphone sounding constricted or over-damped, which is how I felt the PM-1 sounded. The lessened treble itself wasn't inherently a huge deal, but it's just a part of the picture. The way I see it, fill in that treble dip and boost the upper end response just a bit, along with adding a greater subjective sense of air, and you have a very fine headphone indeed (even if it were at $700-1K, IMO).

 

I have no qualms if someone loves the PM-1. I liked it quite a bit, but had reservations and certainly wouldn't pay that price for it. To each his own.

 

Like I said, I don't think the distortion spike is a big deal. I'm not sure it is entirely inaudible, but I certainly don't think it is problematic (probably not audible in most listening situations for most people). At worse, it made them sound a bit warmer, and I think I've even seen a rough set of measurements for a modded PM-1 (may not have been a production model) that was able to iron this out. In other words, it's not necessarily inherent to the driver, enclosure, or pads, and could just need a better damping scheme.

 

That is correct that the treble bump is often seen in the 8-10KHz range, depending on the measurement setup. I can't speak for whether or not mine is more or less accurate than others, but I do use a solution like BMF (WM61A mic glue into tri-flange tip that I insert into my ear). In theory, the human head coupler has some inherent benefits over a "dedicated" measurement rig (i.e. it represents a real scenario by me using my ugly head), but there are many other factors, such as mic placement and insertion depth in the ear, along with associated compensation curves, that remain to be fully answered. And I have experimented with a lot of compensation curves. I ended up settling with a simple one, one that just corrects for the inherent bass roll-off from the mic's phantom PSU. I was pleasantly surprised at how my results turned out relative to my hearing and other measurements (using the HD600 as a sort of reference point, since it has been measured so many times elsewhere). At worst, there's variation already seen across each measurement system to date, so I'm not too concerned if my measurements don't match perfectly with others out there.

 

Anyway, I didn't plan on going that much into detail about measurements or going off topic, but there you have it. It gives context to the results and my subjective thoughts, at least. Probably not best to linger on this topic too much. Like I said, PMs are always welcome!

post #2288 of 2545

The threshold of perception for response deviations in music is about 3dB. If it is a gradual shift without spikes or dips, it's even higher. That response curve is how flat sounds... no warm, no detailed, no in your face... smack dab down the middle.

post #2289 of 2545

More correctly, the overall tilt from 20Hz to the peak I measured at 10Khz is around a 6-7dB difference, not counting for the 5-10Khz section. It's not enough to say, oh, the response only deviates by so many decibels if you use, say, 1KHz as the reference point. That only gets you so far, so you must look at the curve in a holistic manner as well. Consider an imaginary, linear line drawn to average the entire response. What would it look like? This tilt is certainly audible and gives them a somewhat warm, dark characteristic (which I like). It is certainly not "smack dab down the middle" unless you skew or tilt what you consider to be the middle. This is easily noticeable compared to something that measures more flat/neutral from 20Hz to, say, 10KHz (because, like you, I'm less concerned about stuff above 12KHz or so, as I find it often doesn't really correlate one way or the other to my listening enjoyment much in the grand scheme of things).

 

My HE-500, for example, has a flatter overall curve than the PM-1 (my measurements are out there somewhere :wink_face:), and it subjectively sounds more neutral than the PM-1. However, it does have some particular dips that make the response overall a bit less linear (linear =/= neutral) and smooth than what you get with the PM-1, so it has some slightly "wonky" subjective characteristics relative to the PM-1 despite being more neutral sounding overall. (The PM-1 has some other particular, subjective characteristics that are harder to capture with normal measurements, if at all possible to capture.)

 

Long story short, overall response tilts like what the PM-1 show certainly exhibit certain audible characteristics, in this case, making the PM-1 a warmer, more laid-back sounding headphone as a whole. Nothing inherently wrong with that...not everything has to or should be perfectly neutral, though there becomes a certain point where you have to draw a line with $1K headphones relative to products at the price range and, especially, what you can find for less. Even if you disagree, at the very least, that chunk taken out around 5-10KHz is certainly within the threshold of audibility, and likely the main reason these sound so laid-back and a bit warm. I think they would sound completely veiled if not for that (relative, localized) treble peak, which adds a tasteful sense of detail.

 

Again, that's not to say there's anything wrong with this sort of response. I prefer a darker tilt and, because of this, would probably more likely want to listen to the PM-1 than the HE-500 despite its faults.


Edited by hans030390 - 8/9/14 at 12:04am
post #2290 of 2545

It's smooth though so you you would never be able to perceive that gradual a shift. And 10kHz it all the way up to the last octave.

post #2291 of 2545
Quote:
Originally Posted by bigshot View Post
 

It's smooth though so you you would never be able to perceive that gradual a shift. And 10kHz it all the way up to the last octave.

 

You state a 3 dB threshold, but fail to give a frequency range for that threshold (e.g., a 3 dB drop over a 1000 Hz range, etc.).  Is it a change in time (if so, then reduce the time interval, you'll hear the difference as that's what's graphically shown) if you're referring to a freq sweep?  You fail to define exactly what smooth is.  If it's a 3 dB change over the entire range (20 Hz - 20 kHz, the Oppo doesn't fit that definition).  Is that numerical threshold even a constant (I say not)?  In other words, it would make much more sense that that threshold would be smaller as you hit the 1-2 kHz range as humans are naturally more sensitive to that and larger at frequencies above, say 14000 Hz, and lower than, say 50 Hz.  At those highs and lows, the human sensitivity might be a lot lower than that at 1-2 kHz.  Then there is the whole slew of psychoacoustic effects that may not be accounted for (if you're using a real-time, continuous frequency sweep).  

 

I also want to know this source of yours that states this.  Perhaps some scientific paper or research?  Additionally, as Hans has stated, the graph shows spikes and dips, especially when you hit the 10 kHz range that are greater than 3 dB in difference.  Also, it's been shown that people can tell the difference between a gradual slope in signature (about the same amount as the Oppo actually) in contrast to a more perfectly flat one (e.g., DF compensated).  This was, more or less, shown in the Harman Research (though theirs was a 10 dB differences overall; though the Oppo is around 8-15 if you don't include the roll off at the end (depending on where you start and end measurement) and nearly 25 dB if you do include the roll off.  In a way, their research shows that people do prefer this signature over the standard neutral (DF compensated) one.  In order to prefer this signature, they have to be able to tell the difference (and the overall change in sound pressure is less than or equal to that of the Oppo).  I've stated this a few times already, but the Oppo curve represents something close to the OW curve.  This is the reason why a lot of people (including myself) enjoy the sound.  Not neutral (DF compensated) != bad.  

 

I've auditioned and listened to both the PM-1 and (older) PM-2.  Neither are neutral to my ears.  As stated by Hans, the PM-1 (I agree with him here) has a warmer tonality to it while the PM-2 was sweeter in the midrange but also edgier in the treble.  I'm not sure what has changed in the PM-2 since Chicago, so I can't comment on the final model.  

post #2292 of 2545
Quote:
Originally Posted by bigshot View Post
 

It's smooth though so you you would never be able to perceive that gradual a shift. And 10kHz it all the way up to the last octave.

 

Perhaps it varies from person to person. I would be interested to see what you'd think of my HE-500 (curve is flat on average on my system) and the PM-1 I borrowed (measurable dark tilt from 20Hz to 10KHz on my system). You know, just so it's not different hardware setups, potential product variation, and listening conditions that might affect any thoughts on the matter (so, an entirely hypothetical situation!). I've stated my thoughts on what I heard between the two, and I'd be curious to see what you'd think in the same situation. Would you perceive them as roughly the same, as it seems you would based on what you're saying here, or would you indeed hear the sound signature differences like I do? Only H2 TV series and their wild speculations will provide answers.

post #2293 of 2545
Quote:
Originally Posted by tinyman392 View Post
 

You state a 3 dB threshold, but fail to give a frequency range for that threshold

 

I'd be happy to clarify that for you... I'm applying the specs of the human ear to the specs of the headphones here. For human ears, +/-3dB is the just noticeable difference (JND) threshold for response imbalances in music. (For tones, it's somewhere between +/-.5dB and 1dB) If headphones have bumps and dips that don't exceed 3dB, they are doing damn fine in my book, because they sound flat to human ears, even if they aren't totally flat on paper. The most important frequency range to get as flat as possible are the ones between 30hz and 10kHz, particularly through the area where human hearing is most sensitive (1kHz to 5kHz - Fletcher Munson). Above 10kHz, the human ear is much less sensitive to response imbalances. As long as an imbalance doesn't go too high (and create piercing headaches), it doesn't matter so much way up there.

 

Igor Levitzky did an excellent job of balancing the compromises of production by focusing on what people can actually *hear*, not just mechanically trying to make it look good on paper. That's the problem with a lot of armchair hifi reviewers. They don't know enough about the limitations of their own hearing ability, so they focus on things that just don't matter (super audible frequencies, response deviations and distortion below the JND threshold, noise floors that are completely inaudible at normal listening levels, etc.)

 

Hope this clears it up for you.

 

Quote:
Originally Posted by hans030390 View Post
 

Would you perceive them as roughly the same, as it seems you would based on what you're saying here, or would you indeed hear the sound signature differences like I do?

 

Measuring the same should be the same as sounding the same all things being equal. But sometimes mechanical stuff can affect the sound. The very first beta version of the PM-1s they sent me to evaluate had a really tight clamping pressure... uncomfortably so. It also had a much different response above 3kHz. I don't know if the two were related, but they might have been. I'm sure that two sets of cans can measure the same but sound different to someone because of different ways the cups sit on the ears. I don't know about your other headphones though, because I've only had the opportunity to test the PM-1s.


Edited by bigshot - 8/9/14 at 12:44pm
post #2294 of 2545
Quote:
Originally Posted by bigshot View Post
 

 

I'd be happy to clarify that for you... I'm applying the specs of the human ear to the specs of the headphones here. For human ears, 3dB is the just noticeable threshold for response imbalances in music. (For tones, it's somewhere between .5dB and 1dB) If headphones have bumps and dips that don't exceed 3dB, they are doing damn fine in my book, because they sound flat to human ears, even if they aren't totally flat. The most important frequency range to get as flat as possible are the ones between 30hz and 10kHz, particularly through the area where human hearing is most sensitive (1kHz to 5kHz - Fletcher Munson). Above 10kHz, the human ear is much less sensitive to response imbalances. As long as an imbalance doesn't go too high (and create headaches), it doesn't matter much way up there.

 

Igor Levitzky did an excellent job of balancing the compromises of production by focusing on what people can actually *hear*, not just mechanically trying to make it look good on paper. That's the problem with a lot of armchair hifi reviewers. They don't know enough about the limitations of their own hearing ability, so they focus on things that just don't matter (super audible frequencies, response deviations and distortion below the JND threshold, noise floors that are completely inaudible at normal listening levels, etc.)

 

Hope this clears it up for you.

 

I need a source for this statement...  It's a huge statement that needs qualification.  I feel that 3 dB is a bit large of a threshold and that the actual threshold is much lower, closer to around 1-2 dB, depending on the range and locations of frequencies involved (e.g., 1-2 kHz range).  

 

Please cite a paper or research done by anyone that backs up any of your claims.  

 

How do we know what can actually be heard vs what can't?  I've seen people say that 2 dB isn't audible (which means 3 can be), some push the threshold to 3 dB, some go lower than 2.  Personally, if I do a +/- 1 dB parametric EQ around a large enough span (Q) around the 1 kHz range, it's audible despite being a mathematically smooth function.  

 

I want to know where you get the 3 dB number from.  It seems like it's a matter of personal opinion rather than something that is backed up by any sort of source.  The rest of your information seems to be pretty much in agreement with mine, but stating that humans can't hear a roll off past 10 kHz may also be a misleading statement.  

post #2295 of 2545

Well, here is a start...

 

http://www.head-fi.org/t/645851/the-most-important-spec-sheet-the-human-ear

 

This has info on the JND with tones at different frequencies (.5dB to 1dB)

https://courses.physics.illinois.edu/phys406/Lecture_Notes/P406POM_Lecture_Notes/P406POM_Lect5.pdf

 

Lots of pertinent stuff from Ethan Winer here...

http://www.audiocircle.com/index.php?topic=102691.0

 

See also Ethan Winer's excellent youtube videos. He is really good at putting abstract specs into real world applications.

AES Audio Myths Seminar: http://youtu.be/BYTlN6wjcvQ
AES Damn Lies Seminar: http://youtu.be/Zvireu2SGZM

 

Quote:
Originally Posted by tinyman392 View Post
 

but stating that humans can't hear a roll off past 10 kHz may also be a misleading statement.  

 

Again... the pertinent part of that statement is "IN MUSIC". In general, thresholds of perception are much higher *in music* than with steady tones. I'm sure it would vary, depending on the type of music, frequency range and Q width, but 3dB is a pretty conservative benchmark spec for it. Also, the higher you go in frequency above 10kHz, the less important it is to the reproduction of music. Rolling off the top octave (10kHz to 20kHz) has much less of an impact than rolling off any other octave in the range of human hearing. I don't have time to dig through all of this to find specific cites, but I'm sure it's all in here. I hope you find these links useful.

 

If you get a chance to play around with a good equalizer without a lot of spill, take a really well recorded piece of music and try rolling the top end off bit by bit. Figure out where your own hearing thresholds are. In practice, they are probably not quite as good as the conservative figures I am citing here for typical human hearing.


Edited by bigshot - 8/9/14 at 1:52pm
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