Building a Dinner Theater w/ DIY Speakers, Subs, etc... - Page 4 - AVS Forum
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post #91 of 585 Old 02-27-2012, 10:10 PM
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Quote:
Originally Posted by paulspencer View Post

....

Couple of points about the F20 - I've built one and simulated with different drivers. Seems to work best around 20 - 60 Hz, I doubt you will get good results running up to 80 Hz because it is a highly compromised horn. A full sized 20 Hz horn can be made to extend up high, but it must be far bigger. Also, the horn does not protect the driver well below about 25 Hz, so as a rule it's a good idea to run a high pass at that point. Probably around 2nd order.

How low do your mains go? I suspect you might have a bit of a gap between your mains and where the F20 would like to work. You don't really want a 12" low sensitivity sub in your situation. Perhaps a better solution is ported mains that can get down to 60 Hz, high pass at that point and F20 running up to 60 Hz. I'd be wanting to measure to ensure a good integration. Rythmik audio have an article about phase alignment of mains and subs, with either sealed or ported mains:

http://www.rythmikaudio.com/phase1.html

Not trying to ruffle any feathers here, just want to add a couple points of clarification - what you guys built/measured was an adaptation of the F-20 to work with some drivers that were in hand, not one built with the recommended driver to my design.

My testing indicated clean bandwidth to 100 Hz. I had no problem using mine with a 100 Hz crossover. Dutch's mains are far more capable than mine.

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post #92 of 585 Old 02-27-2012, 10:15 PM - Thread Starter
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Lilmike...how does what you just said translate to my particular configuration? I understood the 390HF to be a similar match to the MFW. I suppose I have yet to see anyone actually measure the 390HF. I have one built... I just don't have an amp to run it yet. Also, what exactly is everyone using to measure these? I suppose it is time to fork out some money for metering tools. Suggestions?
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post #93 of 585 Old 02-27-2012, 10:25 PM
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Mike, no feathers ruffled here. Yes, that one used a pair of 10" drivers, but I've modelled various drivers with similar (simulated) results. I have not experimented a great deal with the top end but I am a little surprised if you found good results up to 100 Hz. Relatively high Q peaks typical of a compromised horn suggests problems in doing this, although I haven't spent the time measuring and integrating to be sure. My initial quick measurements and setup indicated poor results going up to 80 Hz but a much better result limiting the top end to 60 Hz before the peaks kick in.

Quote:
Lilmike...how does what you just said translate to my particular configuration?

Mike is saying you can run F20 up higher than I'm suggesting. My sugestion is to not completely believe either of us, but measure, try it our for yourself and see what is the best you can come up with.


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post #94 of 585 Old 02-28-2012, 03:30 AM
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I think what dutch is trying to get at is he needs to figure out how to best use the stuff he has. He has 4Pis and F20s with RSS390HF drivers. With some EQ, he should be able to cross higher than 60Hz.

I'm sure he'd rather have an unlimited budget and Synergy horns and Danley CineMonsters all around, but cost was an object here, and while a basshorn redesign would tame the peaks higher up in the freq range, he will be using four of them, which will smooth out the peaks even more if clustered.

Will the cross at 80-100Hz work? More than likely. Should he cluster his subs? Parham says no, but the crossover frequency chosen WILL dictate this. The lower the crossover, the better separated subs will work. In a living room, separated subs have shorter differences in arrival time, making a higher crossover point feasible, as cancellations due to arrival time differences are higher in frequency, so the subs can cancel room modes and not have a detrimental effect.

In a larger room with separated subs to cancel modes, you must deal with the fact that the 'sweet area' is made smaller the higher your crossover point to mains. Ideally, dutch would place the subs around the room to cancel modes, and crossover low enough that arrival time discrepancies for all 'good seats' would not cause cancellations.

But dutch is faced with real limitations as far as placement is concerned. Clustering the subs is not a bad idea given these limitations, and will allow a higher crossover point. Will the modes in the room affect bass response in the seating area? Yes, and EQ compromises will be made, just like in any other room, including the ones we all used to have when everyone used to run one sub with no EQ.....

We must remember that most listeners at this dinner theatre will never know the difference, as most folks think HTIB systems sound good...it's hard to remember that almost everyone here at AVS represents a very small fraction of the audio-enjoying public with MUCH higher standards.

dutch, I highly recommend measurement equipment. If you are handy, a lilmike mic with Room EQ wizard and a cheap SPL meter will do well for low freq measurements. For higher freq measurements, a calibrated meter may be a little better, or send the lilmike mic out for calibration. Or if you want a readymade solution, Dayton's OmniMic is a complete measurement and software package.

I am not nearly as concerned with your subs as I am with the height of the 4Pis above the ground, and if the seats closer to the screen will have adequate coverage. Wayne would be the person to ask about this. It may be something you cannot do a whole lot about.

Ultimately, both Mike and Paul are right. You must measure to get the best out of what you have.

But make no mistake: You will have a great theater. The F20s will get you to 20Hz, what nearly all movie houses CANNOT do with 25-30Hz vented subs. The 4Pi is a great and proven speaker. Like any other room (including theaters), there will be some seats better than others.

I'd like to see how this all comes together, this is one of the more interesting projects here at AVS.


JSS
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post #95 of 585 Old 02-28-2012, 04:25 AM - Thread Starter
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@max....thanks for the nice words on our project. I will look into getting the metering equipment...I always end up acquiesing to the expertise of others with qualified opinions; but its a journey. I'm not sure if everyone remembers, but I started out with "in-wall" speakers in my original design. ;-)

As for the height of the 4pis, the horns have a 45 degree "field if view" so-to-speak. It was Parham's suggestion that I put the speakers upsidedown. I will have to go back and look at a diagram I made earlier to see how high the mains get mounted in the baffle wall; but coverage was not an issue, even for those in front (though I can imagine anyone sitting closer than, say 12 or so feet from the screen.

I have many pictures of the overall build that I have not shared yet. When I get more time, I will clean up my build thread for continuity and make it easier to follow. The winery is getting stoned over the next 2-3 weeks, and it already got a new roof. The new main stairs get poured this week, and after the stone comes the spray foam guys. This is why I have to make final decisions soon; as all of the wiring has to be ran prior to insulation installation. Max is right; I believe my overall setup is all but determined - at this point I am just trying to figure out if I should group the F20s all together, or spread them out behind my 14' baffle wall (spaced just over 2' apart). Will placement options limited, the advice to meter and EQ everything is well taken.
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post #96 of 585 Old 02-28-2012, 07:52 AM
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Quote:
Originally Posted by lilmike View Post

Not trying to ruffle any feathers here, just want to add a couple points of clarification - what you guys built/measured was an adaptation of the F-20 to work with some drivers that were in hand, not one built with the recommended driver to my design.

My testing indicated clean bandwidth to 100 Hz. I had no problem using mine with a 100 Hz crossover. Dutch's mains are far more capable than mine.

Quote:
Originally Posted by paulspencer View Post

Mike, no feathers ruffled here. Yes, that one used a pair of 10" drivers, but I've modelled various drivers with similar (simulated) results. I have not experimented a great deal with the top end but I am a little surprised if you found good results up to 100 Hz. Relatively high Q peaks typical of a compromised horn suggests problems in doing this, although I haven't spent the time measuring and integrating to be sure. My initial quick measurements and setup indicated poor results going up to 80 Hz but a much better result limiting the top end to 60 Hz before the peaks kick in.



Mike is saying you can run F20 up higher than I'm suggesting. My sugestion is to not completely believe either of us, but measure, try it our for yourself and see what is the best you can come up with.



Ive tested one f-20, a pair of f-20's, both with MFW, one with a tempest one with an MFW, and both with tempests; Clustered, separated, mouths touching, mouths corner loaded... trust me, in all orientations they had no issues getting to 80hz smoothly with either driver loaded, and in some cases, 100hz was fine as well. IIRC the internal length of the horn was around 10 ft, that would be a good place to start your delay measurements and then adding on distance to LP, but as stated, your response could be completely different, measuring over and above standard audyssey is always a good idea

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post #97 of 585 Old 02-28-2012, 08:13 AM
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Here was my response with 4 F20's and it's limit at 10%THD at my LP. I lose 12 dB's from the subs to my seats so add 12 dB's for a 1 meter spl. I used a 500 watt per sub amp. I was using an 80hz crossover as well.



Here they are EQ'd(I know it is smoothed but it was still flat within the same range)



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post #98 of 585 Old 02-28-2012, 09:41 AM - Thread Starter
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I suddenly feel the need to go with six F20s just to "outdo" MKTheater lol
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post #99 of 585 Old 02-28-2012, 10:41 AM
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Quote:
Originally Posted by dutchswan0311 View Post

I suddenly feel the need to go with six F20s just to "outdo" MKTheater lol

Outdo MK? Just when you get a system that is as good or better than his, you'll find out he's gone through three different systems (all better than what you now have.) That is a losing battle, my friend
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post #100 of 585 Old 02-28-2012, 10:44 AM
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By the way, looking forward to seeing how this turns out for you. This system will likely destroy anything your guests have as a reference for home theater. Keep on it!
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post #101 of 585 Old 02-28-2012, 11:01 AM
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My room is 2100 cubic feet! I was just showing that they go to 100 hz if need be.
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post #102 of 585 Old 02-28-2012, 11:03 AM - Thread Starter
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Originally Posted by RyguyOK View Post

By the way, looking forward to seeing how this turns out for you. This system will likely destroy anything your guests have as a reference for home theater. Keep on it!

Yes, but we will be charging them to watch movies (well....and for their meal and wine as well), so my concern is not being compared to a home theater as a reference point, but to the commercial theaters they frequent. I know I will not be able to match the acoustical treatments of a dedicated movie theater, nor the screen quality (seeing as I have a $5,000 projector budget as opposed to a $125,000 projector budget). However, I want them to walk away thinking "that experience was much better than I expected...quite excellent even...I can't wait to tell everyone I know what a great time I had!"
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post #103 of 585 Old 02-28-2012, 11:17 AM - Thread Starter
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Quote:
Originally Posted by MKtheater View Post

My room is 2100 cubic feet! I was just showing that they go to 100 hz if need be.

My best estimate is that the "ballroom & balcony" area that makes up the "dinner theater" is approximately 21,330 cubic feet. Throw in the stage that is connected to the side of the room and you're now at about 23,700 cubic feet or so.
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post #104 of 585 Old 02-28-2012, 11:24 AM
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I can tell you that with my budget dedicated theater it's better than any but the very best theaters I've been to. At least my friends and I believe it's so. And I'm working with a system that has cost me less for the entire setup than your projector alone. It's amazing what can be done with a little knowledge, elbow-grease, and patience. I have no doubt whatsoever your system will knock your guest's socks off.
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post #105 of 585 Old 02-28-2012, 11:29 AM - Thread Starter
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Quote:
Originally Posted by RyguyOK View Post

I can tell you that with my budget dedicated theater it's better than any but the very best theaters I've been to. At least my friends and I believe it's so. And I'm working with a system that has cost me less for the entire setup than your projector alone. It's amazing what can be done with a little knowledge, elbow-grease, and patience. I have no doubt whatsoever your system will knock your guest's socks off.

My budget for all speakers, amps, wires, cables, projector, AVR, bluray player, etc is $15,000. I am really struggling to hit this number. I will post my budget and selected components for everyone to critique later today. I am sure the amplifier and AVR conversation will prompt a spirited debate ;-)
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post #106 of 585 Old 02-28-2012, 12:28 PM
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You will have as much bass as a local theater but extend to 20-22hz so you will be fine there. Hopefully the speakers can sound big enough for that room. Too bad I didn't sell you my JBL speakers which would have floored that room! The speakers you built will sound great however I hope they can play loud enough for the guests. How far away will they be sitting again? My level of bass would probably scare the customers away which is not good!
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post #107 of 585 Old 02-28-2012, 12:31 PM - Thread Starter
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Quote:
Originally Posted by MKtheater View Post

You will have as much bass as a local theater but extend to 20-22hz so you will be fine there. Hopefully the speakers can sound big enough for that room. Too bad I didn't sell you my JBL speakers which would have floored that room! The speakers you built will sound great however I hope they can play loud enough for the guests. How far away will they be sitting again? My level of bass would probably scare the customers away which is not good!

Distance from screen/sound will vary from about 12 feet to 40 feet.
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post #108 of 585 Old 02-28-2012, 12:37 PM - Thread Starter
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Dumb question: If I delay the mains to match the subs and surrounds... Does the video get delayed as well? Or does my movie turn into a poorly dubbed Japanese flick? I warned you it was dumb. ;-)
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post #109 of 585 Old 02-28-2012, 06:08 PM
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Good AVRs will have an automatic dialogue/sound sync function to account for delays. It should not be that big a deal, though. It's as if the mains will be another 14-16 feet away delay-wise.

You should get decent wall loading with the four F20s. Since the F20 will do near 115dB cleanly down to 21Hz, 3dB for conservative wall loading, 12dB for 4 of them with equal power means a clean 130dB at 1 meter.

At 40 feet away (12 meters): stepwise, you are at 124dB at 2 meters, 118dB at 4 meters, and 112dB at 8 meters, with 106dB at 16 meters, not counting modal reinforcement (and cancellation). Make no mistake, 20Hz at 106dB is some pretty tactile sound power. The F20 can take more power at higher frequencies, giving you 2-3 more dB or so if you highpass at 17-20Hz. Since hardly any recordings have sustained -0dBFS passages (reference level is for peaks), you should be alright without a highpass, and tables close to the screen will watch their glasses move across tables...

Not quite reference, but definitely close, and louder than most are used to. I have only been in a few theaters that can actually playback at reference. Many have their faders 3-6dB low to avoid 'too loud' complaints (which are very real)....and most theaters are simply not well equipped enough to playback at reference cleanly, esp in the LFE department, so 3-6dB down actually sounds better....there is nothing worse than having to sit through a distorted AND loud presentation, hearing the subs and mains distort horribly trying to keep up....

The 4Pis max spl is listed for wall and ground loading, so you may lose a few dB to that, but crossing them higher should yield a little more headroom. Each will lag behind the F20 Pack by ~5dB, with enough for reference out to halfway into the room.

JSS
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post #110 of 585 Old 02-28-2012, 06:19 PM
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Are you sure that free space attenuation applies in a room? A few quick tests in my room agree with Toole that sound attenuates more like 3 db per double distance in a room. This implies possibly more than expected, but then we aren't allowing for power compression. It may be that those two things cancel each other out and you end up being spot on.


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post #111 of 585 Old 02-28-2012, 09:49 PM - Thread Starter
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Keep in mind I will be building a baffle wall behind the AT screen that will have the 4pi mains flush mounted. According to Parham, this is also the ideal environment for the 4pis to operate. I am still looking for the optimal acoustical treatment for screen side of the baffle wall (suggestions?). Also, from what research I have done so far, it looks like MDF is a good material to build the wall out of. Thoughts?
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post #112 of 585 Old 02-28-2012, 11:23 PM
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Dutch, I'm from Central Iowa, Slater as a matter of fact. I'm quite excited about your project. My wife and I will surely visit when it's done. When do you expect to be open for playing movies? Will you play current first run movies? I don't need current movies to keep my interest. I would certainly love to watch older films. What will the seating be like?
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post #113 of 585 Old 02-29-2012, 04:24 AM - Thread Starter
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Originally Posted by sx460 View Post

Dutch, I'm from Central Iowa, Slater as a matter of fact. I'm quite excited about your project. My wife and I will surely visit when it's done. When do you expect to be open for playing movies? Will you play current first run movies? I don't need current movies to keep my interest. I would certainly love to watch older films. What will the seating be like?

Cost will be a major player with the regard to 1st vs 2nd run movies. While seating is an aspect yet to be finalized, I expect we will be able to seat approximately 70 or 80is people on tables of 4-6; less if we don't want anyone's back to the screen (which we obviously don't). In the end, our dinner theater will probably seat around 56 or so.

Right now we hope to have a soft opening around the 4th of July with a grand opening around Labor Day. But, as any DIYer knows - it's not good to promise finish times ;-)
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post #114 of 585 Old 02-29-2012, 05:10 AM
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Quote:
Originally Posted by dutchswan0311 View Post

Keep in mind I will be building a baffle wall behind the AT screen that will have the 4pi mains flush mounted. According to Parham, this is also the ideal environment for the 4pis to operate. I am still looking for the optimal acoustical treatment for screen side of the baffle wall (suggestions?). Also, from what research I have done so far, it looks like MDF is a good material to build the wall out of. Thoughts?

If the 4pi will be flush mounted, any reflective material would be good for boundary support (drywall). I would fill the cavities left behind around the drivers with fiberglass.

Another thing that will be important is the rear wall reflection, and whether it is something that will need some absorption, but that is further down the line...

JSS
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post #115 of 585 Old 02-29-2012, 05:11 AM
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With a 180" screen, will you get enough lcr separation to mount them all behind the screen?

JSS
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post #116 of 585 Old 02-29-2012, 05:57 AM - Thread Starter
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Originally Posted by maxmercy View Post

With a 180" screen, will you get enough lcr separation to mount them all behind the screen?

JSS

I think so...that is a 13' wide screen. Is there a calculator that suggests optimal separation? The current design has the L&R channels 60" apart from cabinet edge to cabinet edge of the Center channel, or 78" apart from center of woofer to center of woofer. In the end, it doesn't really matter at this point since that is where they have to go; but it would still be nice to know.
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post #117 of 585 Old 02-29-2012, 06:00 AM - Thread Starter
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Quote:
Originally Posted by maxmercy View Post

If the 4pi will be flush mounted, any reflective material would be good for boundary support (drywall). I would fill the cavities left behind around the drivers with fiberglass.

Another thing that will be important is the rear wall reflection, and whether it is something that will need some absorption, but that is further down the line...

JSS

Correct me if I am wrong, but don't we want the opposite of reflective material on the screen side of the baffle wall? I understand that the whole point of the baffle wall is to absorb sound reflection off the back of the screen.
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post #118 of 585 Old 02-29-2012, 07:55 AM - Thread Starter
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Originally Posted by MKtheater View Post

Here was my response with 4 F20's and it's limit at 10%THD at my LP. I lose 12 dB's from the subs to my seats so add 12 dB's for a 1 meter spl. I used a 500 watt per sub amp. I was using an 80hz crossover as well.

MK....We're you actually running 500W through your drivers? Lilmike had advised not to run more than 300W... even through a 500W driver; but he never attempted nor measured such a thing. It would be exciting if I can safely run 500W through the 390HF with clean results. :-)
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post #119 of 585 Old 02-29-2012, 08:18 AM
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MK....We're you actually running 500W through your drivers? Lilmike had advised not to run more than 300W... even through a 500W driver; but he never attempted nor measured such a thing. It would be exciting if I can safely run 500W through the 390HF with clean results. :-)

I ran 800 watts or so (EPX4000) through my tempest x-2's in the f-20's and they were just fine

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post #120 of 585 Old 02-29-2012, 08:25 AM
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Originally Posted by dutchswan0311 View Post

MK....We're you actually running 500W through your drivers? Lilmike had advised not to run more than 300W... even through a 500W driver; but he never attempted nor measured such a thing. It would be exciting if I can safely run 500W through the 390HF with clean results. :-)

My amp was rated for 500 watts but I doubt I ever needed that much.
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