Finally we have a simple way to rate and compare subwoofers! - AVS Forum
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post #1 of 197 Old 11-27-2013, 10:00 PM - Thread Starter
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For a long time I have been looking for a simple direct way to compare subwoofers so we can make sure we are getting our money's worth. The first stop on my journey was to look at output; how loud do these subs get? But then it occurred to me that output only tells part of the story, for what difference does output matter if the subwoofer isn't following the source signal? At that point I looked at frequency response, it seemed important, as you generally want the amplitude to correspond to the frequency; you don't want notes from the first octave to be played back quieter then the second octave when they are the same level in the recording. And there is the matter bandwidth- you'll be missing notes entirely if they aren't in your sub's range. But then I thought, how cleanly are these notes being played back: distortion can grime up the signal and harmonic distortion can even add notes that aren't there! And then there is the matter of transient response; attack and decay must be faithful to the recording also or it will be completely mangled! And when I learned about cabinet resonance, port overhang and chuffing, intermodulation distortion, room gain, compression, group delay, cumulative spectral decay plots, and so on, my little head got dizzy and I just about fainted!

But all that commotion is a thing of the past, now that we have the PSA Value Factor™!

Ladies and gentlemen, allow me to explain,..

It's simple; we merely use Power Sound Audio's unverified CEA averages of their own products as a reference by which all other subs can be judged! Kindly direct your attention to our first exhibit:

it's as easy as that! No more need to fuss about context! No more wringing your hands over trivial matters like compression, distortion, and linearity! Are you the proud owner of an SVS SB12 but curious how it fares against other subs? We can see very plainly that you need 2.6 SB12s to equal a single PSA XS15. Or, to state that another way, you own 38% of a XS15. For all you who have Hsu ULS-15s, know that you have a whole 90% of a PSA XS15, or a PSA Value Factor™ of 1.1! "But wait", you may protest, "can subwoofers really be reduced to a single number?" To that I say, don't you see, my friends, that ambiguity is a part of of its charm! Pay no mind that all these measurements were culled from different data sets, because with the PSA Value Factor™, such matters are somehow rendered blissfully irrelevant.

Lets walk through a few more examples...

Wondering how your SVS SB13 fares? Why it's a PSA Value Factor of 2.8 with respect to a XS30. In other words, a whole 35%. Who cares where this data came from or how it was acquired- all that stuff is for nerds! NERDS! "In-room extension? How did you come up with that frequency?" "GET THAT NERD!"


How does your Hsu VTF15h stand up to a Power Sound Audio XV15? Here we see it's a 1.2, or 83% of a XV15, despite the VTF15h besting the XV15 in almost every single CEA measurement and destroying it in compression, group delay, decay, and distortion performance. But thankfully we no longer need to pay attention to all that superfluous detail anymore- we have the PSA Value Factor™! PSA Value Factor™! PSA Value Factor™! ....
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post #2 of 197 Old 11-28-2013, 04:48 AM
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That was entertaining. smile.gif
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post #3 of 197 Old 11-28-2013, 06:22 AM
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+1 As a newb looking for my first subs, my choice seems obvious now...
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post #4 of 197 Old 11-28-2013, 06:43 AM
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Wow

I am now an informed consumer!
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post #5 of 197 Old 11-28-2013, 06:47 AM
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Quote:
Originally Posted by fr8doggr View Post

+1 As a newb looking for my first subs, my choice seems obvious now...

Take everything shadyj says with a grain of salt, he takes every opportunity he gets to trash PSA and before that SVS and push HSU. Maybe someone from PSA or SVS ran over his dog when he was a kid.

Check out the description under his name in this forum, pretty much sums it up:

http://forums.audioholics.com/forums/subwoofers/88087-dual-subs-hi-fi-2ch-music-2.html#post1000951
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3 - JTR 228's LCR (game room)
2 - DIY Sound Group V-8 Coaxials (game room)
4 - PSA Triax's (game room)
2 - SVS SB13+'s (living room)
1 - SVS SB12-NSD (bedroom)
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post #6 of 197 Old 11-28-2013, 07:37 AM
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↑↑↑ Nice descriptor!

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post #7 of 197 Old 11-28-2013, 07:45 AM
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Originally Posted by raynist View Post

Take everything shadyj says with a grain of salt, he takes every opportunity he gets to trash PSA and before that SVS and push HSU. Maybe someone from PSA or SVS ran over his dog when he was a kid.

Check out the description under his name in this forum, pretty much sums it up:

http://forums.audioholics.com/forums/subwoofers/88087-dual-subs-hi-fi-2ch-music-2.html#post1000951

The Bold, and description of him made me lol, I guess the old saying of "There's one in every crowd" still applies eh wink.gif
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post #8 of 197 Old 11-28-2013, 07:53 AM
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One thing I don’t like though, is why always such poor examples of the PR alignment? (SC) Maybe because most of them out there are, lol.. little fart boxes albeit extension/potent for size. Although more or less $$, I would rather see these in the comparisons.

http://www.funkaudio.ca/18.3_Overview.html

http://www.funkaudio.ca/15.3_Overview.html

http://creativesound.ca/details.php?model=Quartet12XD%20Subwoofer%20Kit

Being that they’re custom or DIY has no bearing of course when it comes to this situation. tongue.gifsmile.gif

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post #9 of 197 Old 11-28-2013, 06:00 PM
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Quote:
Originally Posted by raynist View Post

Take everything shadyj says with a grain of salt, he takes every opportunity he gets to trash PSA and before that SVS and push HSU. Maybe someone from PSA or SVS ran over his dog when he was a kid.

+1

For those of us who know the other side of the story your description is a lot more accurate than you may realize (well, not the dog part though - no animals were harmed in the making of his personal vendetta tongue.gif).
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post #10 of 197 Old 11-28-2013, 06:27 PM
 
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You can always go with; he wasn't allowed to play with the dog. tongue.gif

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post #11 of 197 Old 11-28-2013, 10:30 PM
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Maybe he wasn't allowed to have a puppy and why all the anger...but his reputation or moniker over at AH is well earned I'd suspect but I had nothing to do with it...biggrin.gif. But yeah...well before PSA it was Svs...and we know the common denominator in both these cases...enough said!
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post #12 of 197 Old 11-29-2013, 12:44 AM - Thread Starter
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Nothing but personal attacks from PSA owners, why am I not surprised? Oh that's right, I remembered, because PSA's asinine marketing can not be defended. Always easier to attack the messenger. But don't worry guys, your subs are really awesome- you have reassurance from the PSA Value Factor. And boy, am I glad I wasn't foolish enough to buy a PB13 Ultra when I could have a XV30, after all the PB13 is only 71% of the sub that the XV30 is according to the PSA Value Factor, despite the fact that the PB13 is using one of the best drivers in any commercial subwoofer, and the XV30 may well be using some of the very worst at it's price point.
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post #13 of 197 Old 11-29-2013, 05:28 AM
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Oh come on, like the reasoning for this whole post isn't a personal attack?

'The 15" driver itself is constructed on a stamped steel frame with a cork front gasket and uses a pressed paper cone with a large black inverted dust cap. The suspension system consists of a very large foam half roll surround and what appears to be a single 6" spider. The single voice coil appears to be 2.5" in diameter and the motor is a simple modestly sized unit that utilizes a single 6" diameter 1" thick magnet slug and a top plate of about 8mm thickness. The back plate is bumped out to clear excursion and has a small pole vent about a half inch in diameter. The motor seems to indicate that this is not what would be considered a high power driver with a lot of xmax but the bumped back plate and oversized surround along with the observed and measured performance indicate that it is a soft bottom motor limited design that likely has the coil leaving the gap entirely before mechanical bottoming can occur. It is not a particularly powerful or visually impressive driver and it is likely very inexpensive to manufacture'

This is from the data-bass review of the HSU VTF-15H, a stamped steel frame on a $1000 subwoofer???

So after you listened to the Power X line and took out the drivers for inspection, what basis did you use to determine the drivers are some of the worst?

Here is a review from josh ricci of the PSA XV15 for anyone who hasn't read it

http://www.audioholics.com/subwoofer-reviews/xv-15-subwoofer
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post #14 of 197 Old 11-29-2013, 05:50 AM
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From Josh Ricci:

"The 15” driver used in this system is constructed on a 12 spoke cast aluminum frame and uses a heavy pressed paper fiber cone with an inverted dust cap. The surround is a large half roll of Rubatek foam which should allow generous excursions. The voice coil is a 2” diameter copper flat wind with an 8” poly cotton spider providing centering and returning force. The motor is comprised of a triple stack of y35 grade magnets of about 5” diameter and a vented pole piece to remove heat from the gap. This driver appears to be sturdy, heavily built for a subwoofer selling in this price class and capable of withstanding large excursions. Power Sound indicates that the driver is capable of 2” peak to peak stroke."

However, according to the OP, PSA uses cheap drivers? Come on, what is your specific agenda here? Seems like there is something "Shady" behind his post, pun intended...

Audioholics has it spot on, check out his moniker...

"shadyJ a forum troll idiot that just begs for attention"
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post #15 of 197 Old 11-29-2013, 05:55 AM
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Here is a review from josh ricci of the PSA XV15 for anyone who hasn't read it
Impressive review. But who is this "Josh Ricci" guy, anyway, and what does he know about subwoofers?! wink.gif
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post #16 of 197 Old 11-29-2013, 06:35 AM
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post #17 of 197 Old 11-29-2013, 06:42 AM
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Originally Posted by eljaycanuck View Post

Impressive review. But who is this "Josh Ricci" guy, anyway, and what does he know about subwoofers?! wink.gif

I dunno!? But I would like him to come over here and test out my aunt Leslie (if he does reviews) who is in the adjoining room sawing logs! I predict the XV15 or any other sub for that matter can’t compare. rolleyes.gifwink.gif

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post #18 of 197 Old 11-29-2013, 08:19 AM
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"troll idiot just begs for attention"....I wanna thank the mod who gave him that moniker likely from his slighting Svs products time and time again over the past several years...yet... he uses Svs products in trying to make his point....what a joke.

Dude we get it...time to move on!
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post #19 of 197 Old 11-29-2013, 09:15 AM
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All right, I told myself I wouldn't get involved in this thread because I didn't want to encourage shady. It's obvious that he just wants attention and we're reinforcing his behavior by responding. 

 

A few weeks ago I asked shady what his educational and professional background was regarding subwoofer driver and amplifier design. His reply was as follows:

Quote:

Originally Posted by shadyJ View Post

Hopinator I have zero authority to talk about drivers or speakers. I am not in the audio industry, and my educational background does not concern audio. Any claims I make should not be taken at face value and should be confirmed by reliable sources like the JAES for example. Jim and Tom are going to know way more than I do about subwoofers. They could school me if they wanted. On the other hand, I am not selling anything. Outside of my own biases I have no reason to mislead anyone.

 

Enough said!

 

His opinions are based on nothing but personal bias, those are his own words. When he talks about the quality of construction of a subwoofer it has to be taken with a grain of salt. He brings zero credentials to the table. 

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post #20 of 197 Old 11-29-2013, 09:37 AM
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Originally Posted by Hopinater View Post

All right, I told myself I wouldn't get involved in this thread because I didn't want to encourage shady. It's obvious that he just wants attention and we're reinforcing his behavior by responding. 

A few weeks ago I asked shady what his educational and professional background was regarding subwoofer driver and amplifier design. His reply was as follows:
Quote:
Originally Posted by shadyJ go_quote.gif


Hopinator I have zero authority to talk about drivers or speakers. I am not in the audio industry, and my educational background does not concern audio. Any claims I make should not be taken at face value and should be confirmed by reliable sources like the JAES for example. Jim and Tom are going to know way more than I do about subwoofers. They could school me if they wanted. On the other hand, I am not selling anything. Outside of my own biases I have no reason to mislead anyone.





Enough said!

So the guy gives you an honest answer and recommends you do your homework and crosscheck his opinions. Then you come here and beat him over the head with it. Nice.
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 His opinions are based on nothing but personal bias, his own words.

Other than the manufacturer reps around here and guys like Bosso and Bill F, who's aren't?
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All right, I told myself I wouldn't get involved.....

Do not feed the trolls and you know what happens when Gremlins get wet. wink.gif
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post #22 of 197 Old 11-29-2013, 11:08 AM
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So the guy gives you an honest answer and recommends you do your homework and crosscheck his opinions. Then you come here and beat him over the head with it. Nice.
Other than the manufacturer reps around here and guys like Bosso and Bill F, who's aren't?

You might be right tack. That may have been a low of me. If so I apologize. And I have told shady more than once in different threads I appreciate his knowledge, because he has a lot of it in certain areas. But maybe what makes a quality subwoofer component is not one of them (at least not in the case of what he believes about the PSA components) so if he is going to put himself out there with definitive statements that a certain manufacturer is making sub-par equipment then he had better expect to be called out on it.  If I say I like something or don't like something that's one thing, that's opinion and it's obvious. If I say that I think something is of poor quality than that's an opinion. If I say that something is of poor quality than I'm stating a fact and that has to be held up to scrutiny. Which is what I believe I was doing here. If I did it in a classless manner than I apologize. My bad. 

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post #23 of 197 Old 11-29-2013, 11:15 AM
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... If I say that I think something is of poor quality than that's an opinion. If I say that something is of poor quality than I'm stating a fact and that has to be held up to scrutiny.
I agree. And I do have some trouble with shadyJ's definitive-sounding attacks on PSA's components and build quality.

That said, I do agree with him that the "PSA Value Factor" is a bit of a joke. But since it's being stated as a fact, no one should object to it being held up to scrutiny.
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post #24 of 197 Old 11-29-2013, 12:06 PM
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Originally Posted by eljaycanuck View Post

I agree. And I do have some trouble with shadyJ's definitive-sounding attacks on PSA's components and build quality.

That said, I do agree with him that the "PSA Value Factor" is a bit of a joke. But since it's being stated as a fact, no one should object to it being held up to scrutiny.
+1. It is too broad and deceptive. It would make sense if they defined the components in the equation that equal = PSA Value Factor, what % of each components make up the PSAVF. As for Shady, he isn't doing anything different when compared to the rest of us fanboys. I used to feel the same way about my Epik Empire that a few of you pissed on. I was just as "protective" of Epik and just as hungry for validation of my choice. It is all so friggin dumb in hindsight:rolleyes:. I wish I could go back and slap the crap out of myself:p. Anyway, I don't think Shady loses a second of sleep over this stuff. I wish I could say the same for some of us. There is an ignore function. Use it. I do.

I will be pulling the trigger on a XS30 this weekend. I am hoping that the sound quality at least equals the Empire that I miss so badly, while providing some bonus low end that the Empire lacked. The only reason I haven't pulled the trigger as yet is because I am now realizing that it was probably best to go with the Submersive a long time ago and save myself the headache/expense of switching subs.
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post #25 of 197 Old 11-29-2013, 12:24 PM
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I know looks means very little to a degree (it can tell you things of course) but the first time I saw the PSA driver it reminded me of the MKIII which turned out to be more of a driver than I anticipated. Sometimes (imo) when your going to come to so many conclusions regarding a sub or driver, I think it’s best to experience it first hand.. for what it’s worth, just sayin.



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post #27 of 197 Old 11-29-2013, 12:48 PM
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Originally Posted by eljaycanuck View Post

I agree. And I do have some trouble with shadyJ's definitive-sounding attacks on PSA's components and build quality.

That said, I do agree with him that the "PSA Value Factor" is a bit of a joke. But since it's being stated as a fact, no one should object to it being held up to scrutiny.

Honestly I agree...What PSA should do is remove those charts and simply post cea2010 16-80hz data for each sub like HSU does and be done. Also SVS and Rythmik need to follow suit.
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post #28 of 197 Old 11-29-2013, 12:50 PM
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I will be pulling the trigger on a XS30 this weekend. The only reason I haven't pulled the trigger as yet is because I am now realizing that it was probably best to go with the Submersive a long time ago and save myself the headache/expense of switching subs.
why making the mistake twice? Get the SubM.
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post #29 of 197 Old 11-29-2013, 12:53 PM
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why making the mistake twice? Get the SubM.

Nope! don't stop there, go 21-24" DIY wink.gif

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post #30 of 197 Old 11-29-2013, 01:11 PM
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I am not as adamant as shadyJ biggrin.gif, but yeah this is not a great way to compare subwoofers. I got run out of the triax thread at one point for discussing its measurements, so I think an explanation here is warranted.

First of all lets see how they are getting the dB numbers. They are converting to Pa, then back to dB. Nothing wrong with that, but you must realize that this highly weights the larger number. You can see here how it is done and how it weights the larger numbers this way by looking at the cea average and actual average here.

http://www.audioholics.com/loudspeaker-design/subwoofer-room-size

Now this is all good and fine, but what many don't realize is that this cooks the books so to say for high inductance drivers. Their high dB output at a specific frequency inflates the numbers. For example I will do another subwoofer with a high inductance driver, the eD a7s450.
xs-30 a7s-450
20-31.5 = 116.7 116.9
40-63 = 131.2 128.7
20-63 = 126.7 124.7

So it seems the psa driver have comparable inductance issues since the xs has less 20-31.5, but more 40-63.

Lets look at some graphs with the a7s and the ported xv 15 (so we know more output at tune)





So now we can see how the dsp in the PSA amp is smoothing this out. So what does inductance mean?

Ricci-
"Inductance has a far more negative affect on overall sensitivity than extra motor force IMHO."
"They are car audio drivers for SPL competitions with huge 8 layer coils tons of mechanical noise, inductance through the roof (which actually helps generate peak sensitivity near 50-70Hz) and high distortion which again helps make them louder."
"Even more obscuring is the huge inductance increase which nukes the already low sensitivity and the response shape. As far as a sub drivers voltage sensitivity I still contend that inductance is enemy number one."

See I can cherry pick myself. smile.gif

http://www.avsforum.com/t/1497174/bl-2-re-how-is-this-the-force-factor-in-a-driver/90

So now that we have that out of the way. Lets take a look at the comparison to the vtf 15H. First they got the power wrong, its 350 watts. This way with the inductance hump and the way they present the data, you need 1.2 15H to equal an xv 15 when what we are actually comparing is this.



Now they claim the xv 15 in room extension as 14 hz and the 15H as 17hz? Looking at this graph they look pretty even in extension to me. And this is with the 15H with Q.3, so if it was raised it would be even lower (and the psa uses dsp so why not).



Since they were doing a 20-63 comparison, lets use the 17hz tuning, since you know that only increases the output below 20hz and hurts everything above. In the way they are doing the comparison from 20-63 hz, they should be using the 15H native tuning with two ports open.



2 port mode numbers
20-31 118.7
40-63 124.4
20-63 122

So with 2 ports open its 122 compared to the 121.8 of the psa using this method. It also appears in native response the xv15 is over 15 dB down at 14hz, and in 2 port mode the 15H is over 15 dB down at 17 hz with a q .3.

So in this comparison IMO, the only thing they got right was the price and that the 15H uses a 15" driver. The rest of the data appears skewed in the comparo.

So I think the way they are comparing gives an advantage to high inductance drivers and the data they use is a bit skewed to there products. Also breaking down a 20-63 hz measurement to a single number is far out there. Hey I got no issue with PSA and they are selling subwoofers so rock on. I think they are competitive subwoofers at their price points, I just think the PSA value factor can be taken with a grain of salt.

edit: all numbers and info from data-bass.com. Heck I even pulled out the old TI-82 for this post!
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