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Stereo Integrity's new HT Subwoofer - Page 2

post #31 of 1715
9/25/12 at 7:05pm
Quote:
Originally Posted by Scott Simonian View Post

Didn't the high inductance of the FiCar Q18 effect it's low end sensitivity or is it just a s**t driver in the first place? tongue.gif
.

In a sealed sub it appears to be not so good. It even models bad.
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post #32 of 1715
9/25/12 at 9:37pm
Quote:
Originally Posted by Ghani99 View Post

Thanks for the link. The effects of Le are apparent on the tested 6.5" woofer at 4khz, not sure how this would apply to a sub doing 80hz and down.

Inductance stores energy and is referred to as the inductance hump, which occurs around 60hz, give or take. So what you end up having is stored energy that is released when the driver cone should stop moving and that is what creates that hump, along with a small amount of "ringing", or residual cone movement after the input has ceased. It then models with the hump similar to a high Q alignment (Qtc), but without being in a small enclosure. Once put in a smaller enclosure, the high Q exaggerates the problem...which is awesome if you're into db-drags.
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post #33 of 1715
9/26/12 at 10:25am
Inductance can lower efficiency and sensitivity at the top end and to a lesser extent also at the bottom end. Meanwhile it can create extra near the system impedance peak. It also seems to increase distortion as well but this is probably more related to fluctuation than static value. You need to look at inductance in relation to the driver DCR and also to some extent the MMS. There is a big difference between a 2ohm driver with 4mH and an 8ohm driver with 4mH (Much better). One driver having an MMS of 250g and the other of 500g will also make a difference. at the end of the day the 1khz rating is worthless for subs so you need to look at the impedance curve.

As far as seeing it in the impulse response I suspect that this would be rather difficult. Inductance rolls off the upper frequencies which will have a dramatic effect on the impulse right there. Technically I guess there is some stored energy but it never seems to show up in energy decay plots and when it does it is such a miniscule amount as to probably be completely inaudible especially after the major disaster that is the acoustics of most rooms.
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post #34 of 1715
9/26/12 at 2:15pm
Thread Starter 
Any of you guys watch Breaking bad? We have a bunch of Walter's on this forum.
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post #35 of 1715
10/16/12 at 3:30pm
New info on the Stereo Integrity HT18d2
Quote:
Originally Posted by Electrodynamic;555958 
Here is an image of the impedance plot along with a full list of T/S parameters we received from Josh Ricci at Data-Bass.com. He will be compiling a review of the woofer within the next few weeks. smile.gif

A%20SI%20HT%2018D2%20FREE%20AIR%20IMP.JPG

SI HT-18
Fs = 14.99 Hz
Re = 3.50 ohms[dc]
Le = 10793.23 uH
L2 = 3425.54 uH
R2 = 57.66 ohms
Qt = 0.30
Qes = 0.33
Qms = 2.88
Mms = 446.62 grams
Rms = 14.584034 kg/s
Cms = 0.000252 m/N
Vas = 469.20 liters
Sd= 1150.29 cm^2
Bl = 21.138090 Tm
ETA = 0.46 %
Lp(2.83V/1m) = 92.33 dB
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post #36 of 1715
10/16/12 at 4:43pm
That changes things a bit...

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post #37 of 1715
10/16/12 at 4:49pm
I get a very similar peaky response too.

Awaiting Josh's trials...
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post #38 of 1715
10/16/12 at 5:09pm
I doubt that this one will be peaked like that at all. It has an aluminum pole cap plus an aluminum inner magnet ring and a relatively small 2.5" coil. Look at the impedance curve past the resonance. Drivers with really bad inductance rocket up almost immediately. This one looks good. ARTA is a little weird about the LE. If I remember right it is about 3.3 at 1khz.
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post #39 of 1715
10/16/12 at 5:12pm
Well, I didn't generate the T/S parameters. I just fed them into the software and modeled them. If they're not accurate of how the sub will perform then why release them?
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post #40 of 1715
10/16/12 at 5:54pm
rolleyes.gif
Edited by bossobass - 10/19/12 at 7:00pm
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post #41 of 1715
10/17/12 at 9:14am
Quote:
Originally Posted by Ricci View Post

I doubt that this one will be peaked like that at all. It has an aluminum pole cap plus an aluminum inner magnet ring and a relatively small 2.5" coil. Look at the impedance curve past the resonance. Drivers with really bad inductance rocket up almost immediately. This one looks good. ARTA is a little weird about the LE. If I remember right it is about 3.3 at 1khz.

Very correct. I knew this going in but I was just stating that the results I got using the supplied T/S were similar to Stereodude's with a Le induced peak. Anymore now I always look at the impedance graph and then go from there.
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post #42 of 1715
10/17/12 at 9:21am
Quote:
Originally Posted by bossobass View Post

Like most of the recent driver threads, Le-phobia has fogged a lot of glasses.
I don't model subs but it looks to me at a glance that some of that "peaky" "hump" is a high Qtc.

Nah. The enclosure modeled nets a Qtc under .6 so that is not the issue I believe.
Quote:
Originally Posted by bossobass View Post

Or, as most do here, let some other guy do that and advise you from there.

Heeeeyyyy! Oh wait... tongue.gif
Quote:
Originally Posted by bossobass View Post

As far as the Fi stuff goes, they're long throw overhung drivers. That means they're high Le drivers. Get over it. Even if you add shorting rings, and that's assuming the shorting rings are actually properly designed to short and not just some aluminum rings thrown into the motor, you are shorting high inductance.

Hey, some people like apple pie, some people like pumpkin pie and some people want a pecan. wink.gif

Quote:
Originally Posted by bossobass View Post

What's the benefit of a flat-to-200 Hz sub then? Reduction in HD at cross?

Not having to signal shape that part of the spectrum. Idk. tongue.gif
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post #43 of 1715
10/17/12 at 10:45am
Quote:
Originally Posted by Stereodude View Post

If they're not accurate of how the sub will perform then why release them?

First I didn't release them. I gave them to Nick and he did. Second I never said they weren't accurate.

What you have to realize is that while a complex 3 component inductance model is 10X better than a static 1khz LE value, or none at all, it is NOT a guarantee that the models will match how the system actually performs by any means. It still leaves a lot to be desired and can be way off on some drivers. Actually the trend seems to be that the better the inductance management on the driver the less close the match is. Some quick examples would be the LMS Ultra and Pro5100 which show a pronounced hump using the 3 part model which is decidedly not there in reality. I expect this SI woofer to fall into that category, but I do not know for sure yet. As always acoustic measurement trumps simulation every time. What I do is manipulate the simulation data until it does match the actual measurement. It's a PITA but it is the only way to get a good match on some devices.
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post #44 of 1715
10/17/12 at 11:06am
This may turn out to be an alright driver and as Josh elludes to the printed specs don't speak everything for this driver.

I made this using all the info we have on this driver as of yet.

SIHT18d2LEcompare.gif

Blue: original SI released spec

Red: Ricci extrapolated spec

Green: Ricci Le 1khz corrected spec

Notice that there is VERY little change down low. Good stuff.

Which is the most accurate? Who knows. Like Josh says and I sure have been learning a lot about recently is that there really is no way to tell on these modern style drivers with inductance fighting measures. Kind of frustrating for those of us who like to chair bench and can't just order every driver out there but... what can we do? Right now as these are still non-existent pre-order drivers I'm not excited really. Not until they are in stock with a steady supply.
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post #45 of 1715
10/17/12 at 11:17am
How about a link?
Thank you.
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post #46 of 1715
10/17/12 at 11:19am
A link to what?
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post #47 of 1715
10/17/12 at 11:38am
Quote:
Originally Posted by bossobass View Post

Like most of the recent driver threads, Le-phobia has fogged a lot of glasses.
I don't model subs but it looks to me at a glance that some of that "peaky" "hump" is a high Qtc.

With proper signal shaping (an absolute requirement for any sealed system) the Fi drivers do the job, and pretty well from my experience. Unless you require a minimum 100 Hz cross point, Le is a big bunch of hot air blowin' in the wind. Cross at 80 Hz and the LPF puts you down -6dB at 80 Hz. After proper signal shaping the sub is flat at 80 Hz, so there ya go. What's the benefit of a flat-to-200 Hz sub then? Reduction in HD at cross? Someone please prove that that's the case and that it's audible to 10 out of 10 listeners and I'm paying attention.

First there are subs which might be considered as operating below 120Hz only and there are woofers which might be used up past even 300Hz and there are a very few drivers that can do both well. For woofers inductance is absolutely important IMHO. For subs not as much but I still feel it matters. All else equal I will take the lower inductance model. If I can avoid having to shape the signal even further to counteract a large hump I'd prefer that. Also yes the electrical signal might be -6dB at 80Hz with a low pass set there but how does that act on a sub who's response is already 6dB down from a peak by 80Hz to begin with and rolling off even further from there? Now you are 12dB down at cross with a steeper slope than intended. Matching to the mains is not as easy and your xo point becomes shifted. I don't always cross at 80Hz or lower either, plus even in HT the LFE channel can potentially have power up to 120Hz or so. When I'm looking at a driver I'm not always considering how it will do in a small sealed box in a HT. That is not the only alignment used and HT is not the only application.

Sealed is the very simplest sub to make and the most forgiving and predictable. This is exactly why I use sealed cabs for all of my testing. The more complex the design the larger it will be, the more chances for something to go wrong or be "off" and more difficult it is to compare directly. Without taking into account complex inductance behavior you cannot accurately simulate a bass system. For sealed or IB subs in a small space this does not matter so much. The more complex the system the more important accuracy becomes though. By the time you get into higher order band pass and horn systems the differences in the driver behavior can mean the difference between a good design and something utterly worthless. I design systems for various applications with widely different needs including some horn designs and other experimental stuff I'm working on so knowing the driver inductance behavior is critical for those.

These are just my observations from measuring a bunch of 18" and 21" drivers in the same sealed enclosure. Having a lot of inductance does change the FR shape and as a result the system efficiency and sensitivity. It will increase the sensitivity near the system Fb but it will often dramatically lower it above that point and also below that point. That is the thing it doesn't just lower the sensitivity up top but also at the bottom. If I look at the 1w/1m sensitivity measurements that I have there is a maximum difference of 15dB at 100Hz in the same sealed box. That requires 32X the power from the amplifier to reach the same levels. Additionally at 20Hz there is a maximum difference of 6.5dB which requires over 4X the power from the amplifier. At 80Hz there is a maximum difference of 12.3dB between any 2 drivers. The sub drivers that offer the lowest sensitivity at 100Hz are the same that offer the lowest sensitivity at 20Hz and those are the drivers with a humped up response and high inductance. Sure you can EQ just about anything into any shape that you want but that loss of sensitivity will always be there and it will limit your maximum headroom. This is another case where if i get to choose I will always take more over less. Inductance also results in higher distortion levels away from the system resonances. IOW that would be the deep bass and the upper bass. Now we all know that bass distortion is rather difficult to hear well and generally fairly benign , but...If I get my choice I will take less over more.

Something that Mark S. has mentioned a couple of times but no one seems to take note of is that the content put into our systems is not like test signals and is much more varied and wide bandwidth. For example look at the dragon crash in HTTYD or other very loud, complex wide bandwidth effects. This is where a more linear wider bandwidth device with better overall sensitivity will really start to show its efficiency advantages requiring much less power from the amplifier and less current into the driver motor.

You can still make a great system with high inductance subs...Hell the ones i'm using aren't that great so what's that say? Still there are a lot of solid advantages to controlling the inductance IMHO.
Edited by Ricci - 10/17/12 at 11:45am
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post #48 of 1715
10/17/12 at 11:42am
Quote:
Originally Posted by Ricci View Post

First I didn't release them. I gave them to Nick and he did. Second I never said they weren't accurate.
What you have to realize is that while a complex 3 component inductance model is 10X better than a static 1khz LE value, or none at all, it is NOT a guarantee that the models will match how the system actually performs by any means. It still leaves a lot to be desired and can be way off on some drivers. Actually the trend seems to be that the better the inductance management on the driver the less close the match is. Some quick examples would be the LMS Ultra and Pro5100 which show a pronounced hump using the 3 part model which is decidedly not there in reality. I expect this SI woofer to fall into that category, but I do not know for sure yet. As always acoustic measurement trumps simulation every time. What I do is manipulate the simulation data until it does match the actual measurement. It's a PITA but it is the only way to get a good match on some devices.
Well, less screwing around on the forum and more measuring then. tongue.gif
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post #49 of 1715
10/17/12 at 11:54am
Quote:
Originally Posted by Ricci View Post

First there are subs which might be considered as operating below 120Hz only and there are woofers which might be used up past even 300Hz and there are a very few drivers that can do both well. For woofers inductance is absolutely important IMHO. For subs not as much but I still feel it matters. All else equal I will take the lower inductance model. If I can avoid having to shape the signal even further to counteract a large hump I'd prefer that. Also yes the electrical signal might be -6dB at 80Hz with a low pass set there but how does that act on a sub who's response is already 6dB down from a peak by 80Hz to begin with and rolling off even further from there? Now you are 12dB down at cross with a steeper slope than intended. Matching to the mains is not as easy and your xo point becomes shifted. I don't always cross at 80Hz or lower either, plus even in HT the LFE channel can potentially have power up to 120Hz or so. When I'm looking at a driver I'm not always considering how it will do in a small sealed box in a HT. That is not the only alignment used and HT is not the only application.
Sealed is the very simplest sub to make and the most forgiving and predictable. This is exactly why I use sealed cabs for all of my testing. The more complex the design the larger it will be, the more chances for something to go wrong or be "off" and more difficult it is to compare directly. Without taking into account complex inductance behavior you cannot accurately simulate a bass system. For sealed or IB subs in a small space this does not matter so much. The more complex the system the more important accuracy becomes though. By the time you get into higher order band pass and horn systems the differences in the driver behavior can mean the difference between a good design and something utterly worthless. I design systems for various applications with widely different needs including some horn designs and other experimental stuff I'm working on so knowing the driver inductance behavior is critical for those.
These are just my observations from measuring a bunch of 18" and 21" drivers in the same sealed enclosure. Having a lot of inductance does change the FR shape and as a result the system efficiency and sensitivity. It will increase the sensitivity near the system Fb but it will often dramatically lower it above that point and also below that point. That is the thing it doesn't just lower the sensitivity up top but also at the bottom. If I look at the 1w/1m sensitivity measurements that I have there is a maximum difference of 15dB at 100Hz in the same sealed box. That requires 32X the power from the amplifier to reach the same levels. Additionally at 20Hz there is a maximum difference of 6.5dB which requires over 4X the power from the amplifier. At 80Hz there is a maximum difference of 12.3dB between any 2 drivers. The sub drivers that offer the lowest sensitivity at 100Hz are the same that offer the lowest sensitivity at 20Hz and those are the drivers with a humped up response and high inductance. Sure you can EQ just about anything into any shape that you want but that loss of sensitivity will always be there and it will limit your maximum headroom. This is another case where if i get to choose I will always take more over less. Inductance also results in higher distortion levels away from the system resonances. IOW that would be the deep bass and the upper bass. Now we all know that bass distortion is rather difficult to hear well and generally fairly benign , but...If I get my choice I will take less over more.
Something that Mark S. has mentioned a couple of times but no one seems to take note of is that the content put into our systems is not like test signals and is much more varied and wide bandwidth. For example look at the dragon crash in HTTYD or other very loud, complex wide bandwidth effects. This is where a more linear wider bandwidth device with better overall sensitivity will really start to show its efficiency advantages requiring much less power from the amplifier and less current into the driver motor.
You can still make a great system with high inductance subs...Hell the ones i'm using aren't that great so what's that say? Still there are a lot of solid advantages to controlling the inductance IMHO.

Well said, Josh. Agree with you on this 100%.
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post #50 of 1715
10/17/12 at 12:10pm
yeah, +1, expand that post a bit and post it as an article on data-bass.
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post #51 of 1715
10/17/12 at 1:37pm
wink.gif
Edited by bossobass - 10/19/12 at 7:03pm
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post #52 of 1715
10/17/12 at 2:27pm
hey bosso,

it seems that you are saying that all the work on controlling/minimizing/linearizing inductance in subs is a complete waste. is that right?

if so, what then do you have to say to all the engineers at 18sounds, ae, alpine, b&c, bms, dayton, jbl, re (just to cite a few), who all put inductance control devices in their subs?


"In the singular case of the TC stuff, they use a massive copper pole sleeve to short inductance, which has a chain effect through the rest of the motor and is priced accordingly. The end result is zero net gain when using them as a subwoofer. The difference comes in displacement capability and inductance is irrelevant. I prefer low inductance, if all else is equal, but if I have to pay double or triple for it, I'll pass."

“I am a Submersive HP owner as well. I can tell you that while the SM is a VERY good sub, Warp's "XLERATORS" are very different. Beyond the incredible output, they have a tightness and transparency that sounds very different from the SM. So much so, Warp has me convinced I need to pick up a pair of LMS 18's and follow in his footsteps.” –TJHUB
http://www.avsforum.com/avs-vb/showthread.php?t=1313021&page=3
Edited by LTD02 - 10/17/12 at 3:07pm
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post #53 of 1715
10/17/12 at 3:10pm
eek.gif
Edited by bossobass - 10/19/12 at 7:01pm
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post #54 of 1715
10/17/12 at 3:27pm
Dave,

I'm saying that a long throw driver with good inductance combating techniques will have just as much low bass output as a similar driver without those inductance measures implemented. On top of that it will exhibit:

Higher sensitivity everywhere except over a narrow range where the inductance causes a peak
Higher efficiency as above
Lower distortion as above
Higher output capabilities in the upper bass as well as with broadband signals
Easier load on the amplifier
Flatter easier to crossover response curve, able to be used higher in frequency if needed

A extended stroke sub bass driver with a decent response curve and useful top end can be built and it is not exactly rocket science. I'm not talking about pancake flat response like an Ultra, just something reasonably controlled like a UXL-18 or the LMSR series. Tumult MKII for example.

Oh and the driver you mention is frankly great not just good IMO. I will take that any day over another driver that gives the same 85dB at 10Hz but only 120dB at 125Hz.

I'm using drivers for ht that have dreadful low sensitivty in the upper bass and a bit of peak and they are well up to the job so I get what you are saying. I'm not talking about medium stroke pro woofers here with this talk about inductance. That's not what I'm advocating I'm saying that you can make sub bass pumps with reasonable cost and decent inductance management too so that there isn't a huge peak and it will improve the all around performance not just the top end. They don't have to be crazy expensive either. There are quite a few examples. W15gti, lmsr, epic, sa series from sundown, alpine type r, sdx 12 and 15, mtx 9515, tumult mk2, uxl18, etc...A lot of us would just rather pick one of those over the really peaked ones because of the advantages.
Edited by Ricci - 10/17/12 at 4:03pm
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post #55 of 1715
10/17/12 at 3:30pm
"How many name brands you cite is making no point that I can respond to."

bingo.
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post #56 of 1715
10/17/12 at 8:08pm
...
Edited by bossobass - 10/19/12 at 7:04pm
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post #57 of 1715
10/17/12 at 8:49pm
"Then we have jokers like LTD"

no need to resort to name calling. that only highlights how weak your arguments are on the merits.

i've helped lots of folks around here from simple sealed builds to monster horns with success across the board. all i see you doing is arguing how superior your system is and dodging any questions.

you didn't answer any of the questions on the topic though, so let's try again.

it seems that you are saying that all the work on controlling/minimizing/linearizing inductance in subs is a complete waste. is that right?

if so, what then do you have to say to all the engineers at 18sounds, ae, alpine, b&c, bms, dayton, jbl, re (just to cite a few), who all put inductance control devices in their subs?

"In the singular case of the TC stuff, they use a massive copper pole sleeve to short inductance, which has a chain effect through the rest of the motor and is priced accordingly. The end result is zero net gain when using them as a subwoofer. The difference comes in displacement capability and inductance is irrelevant. I prefer low inductance, if all else is equal, but if I have to pay double or triple for it, I'll pass."

“I am a Submersive HP owner as well. I can tell you that while the SM is a VERY good sub, Warp's "XLERATORS" are very different. Beyond the incredible output, they have a tightness and transparency that sounds very different from the SM. So much so, Warp has me convinced I need to pick up a pair of LMS 18's and follow in his footsteps.” –TJHUB
http://www.avsforum.com/avs-vb/showthread.php?t=1313021&page=3

and for whatever it is worth, i don't doubt your approach dave. for those who have the money, it would kill most everything from big buy stores. our arguments are in the details.
Edited by LTD02 - 10/17/12 at 9:31pm
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post #58 of 1715
10/18/12 at 4:56am
Quote:
Originally Posted by LTD02 View Post

“I am a Submersive HP owner as well. I can tell you that while the SM is a VERY good sub, Warp's "XLERATORS" are very different. Beyond the incredible output, they have a tightness and transparency that sounds very different from the SM. So much so, Warp has me convinced I need to pick up a pair of LMS 18's and follow in his footsteps.” –TJHUB
http://www.avsforum.com/avs-vb/showthread.php?t=1313021&page=3.
Okay, I'll bite. Your post seems to imply that the Submersive has drivers in it with high inductance and the reason TJHUB hears a difference in Warp's XLERATORS is due to the inductance That's quite the leap in deductive reasoning considering it's completely unknown if the Submersive have high inductance characteristics.
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post #59 of 1715
10/18/12 at 6:26am
Quote:
Originally Posted by Stereodude View Post

Okay, I'll bite. Your post seems to imply that the Submersive has drivers in it with high inductance and the reason TJHUB hears a difference in Warp's XLERATORS is due to the inductance That's quite the leap in deductive reasoning considering it's completely unknown if the Submersive have high inductance characteristics.
That, and also the fact that inductance must be silly high to have an effect in the subwoofer pass band, while 'tightness' and 'transparency' are characteristics of the midbass and midrange. Being aware of specs isn't a bad thing, but more important is being aware of whether said specs have an influence on the outcome.
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post #60 of 1715
10/18/12 at 8:31am
\\\\
Edited by bossobass - 10/19/12 at 7:05pm
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