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Setting up surround arrays like a commercial theater; multiple speakers per channel


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#1 of 27 OFFLINE   DanChristensen

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Posted April 19 2010 - 03:37 PM

Ever notice how home surround units, even the big monster and flagship ones, are only made for exaclty one speaker per channel; never more? Also ever notice how all theaters use a plethora of speakers for the surround channels? 

This can't just be because they have a large audience to cover and they try to make the sound decent for everyone even if it takes away from the quality of the sweet spot; something I imagine it must do the timing would be all over the place in the middle with all those speaker lined along a rectangular wall.

Anyway I am setting up a speaker array that uses 3-4 speakers per surround channel. With a 5.1 system. That's right. No theater has ever used more (mainstream), even 8 channel SDDS (less than 100 movies made this way) has ever used more than two surround channels, yet they ALL have many speakers for each one. I am thinking of facing the speakers that will inevitably be closer to me at the sides forward or backward so they don't fire directly at the listener. Then I am putting two speakers significantly higher up in the very back facing forward, not necessarily angled toward the listening area. This should certainly provide for a spacious surround effect, which is the point of the surround channels and the information sent to them which is usually non directional ambience. I don't buy into 7.1, 9.1, or 11.2 yet as there is not enough true source material for them, and I don't have personal experience to tell me weather or not Pro Logic IIx or IIz matrixing is all that great. 

If anyone has any suggestions for such an array I would like to know. My setup is far from cost-not-an-issue, but it benefits from being something perhaps even more rare, looks-no-issue in this case. 


#2 of 27 OFFLINE   Robert_J

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Posted April 20 2010 - 12:29 AM

I don't recommend this.  But if you do go ahead with it, make sure your receiver can drive a low impedance load.  You don't want to let out the magic smoke.


#3 of 27 OFFLINE   Jeff Gatie

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Posted April 20 2010 - 12:51 AM

Surround sound hasn't been "usually non directional ambience" since the advent of discrete surround channels.  You are basing your design on inaccurate information.  I agree with Robert J, unless you are building a theater the size of an actual theater, I'm afraid your sound will be a muddy mess.

#4 of 27 OFFLINE   Jason Charlton

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Posted April 20 2010 - 01:45 AM

In the words of Samir Nagheenanajar, "Yes, this is horrible, this idea."

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#5 of 27 OFFLINE   DanChristensen

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Posted April 20 2010 - 11:48 AM

Okay well it's not commercial theater size, but it has two rows of couches and is a fairly large area. How do all cinemas pull it off acceptably. Don't tell me they time each one a little off so they are all in sync. Besides this would only work to create a focused sweet spot and would make the rest of the auditorium worse. I think I can make it work. And please don't metion impedance. How dumb do you think I am lol. I use multiple amps, not just a receiver.


#6 of 27 OFFLINE   DanChristensen

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Posted April 20 2010 - 12:12 PM



Quote:
Originally Posted by Robert_J 

I don't recommend this.  But if you do go ahead with it, make sure your receiver can drive a low impedance load.  You don't want to let out the magic smoke.
I use multiple amps; I wouldn't do something that dumb.



#7 of 27 OFFLINE   gene c

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Posted April 20 2010 - 12:52 PM

I've read where an additional pair of surround speakers were mounted between the fronts and the original pair of surrounds in a very long and narrow room so those in the middle of the room can enjoy the surround effect better. But I think it would take an experienced installer or a lot of trial and error to set it up correctly. I doubt you're going to find much support for this type of thing on this forum. We're pretty traditional around hear.
 
And I wouldn't try it in anything but a huge room and even then I'd probably screw it up. But it's your room so you're more than welcome to try anything you wish.

In a stretch, you could say some bi-pole/di-pole speakers are two seperate speakers sharing the same cabinet and output channel. Or not  .
"Everyday room": Panasonic 58" Plasma, Dish HD DVR, Pioneer Elite vsx-23, BDP-23 BR, dv58avi universal dvd player, Paradigm Studio 20 V1, CC-450, Dayton HSU-10 subwoofer.

"Movie/Music room": Toshiba 65" DLP, Dish HD receiver, Marantz 7005, CC-4003, BD-7006, Polk LSI25's-LSi7's-LSiC, 2 original Dayton 10" "Mighty-Mites" subwoofers. (subject to change without notice).
 
Also have  MB Quart Vera VS05 +.....too much to list. Help me.
 
 

 


#8 of 27 OFFLINE   DanChristensen

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Posted April 20 2010 - 01:56 PM

I added another reply as a quick reply to the post by Robert_J but it said it would have to be apporved by a moderator as I;m new here. Okay, and lol this happens to me a lot. My first post sounds kind of confusing and you guys might not have fully gotten it. 

But I'm justifiying experimenting with it as all theaters do it. I want to add a URL of a pdf of a commercial surround setup for theaters by JBL but I;m sure my post will be blocked for "approval" if I add a URL. 



#9 of 27 OFFLINE   Jeff Gatie

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Posted April 21 2010 - 02:15 AM

You have two rows, theaters have dozens of rows.  There is simply no need for an array of surround speakers for two rows of seats.  Period.

#10 of 27 OFFLINE   David Willow

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Posted April 21 2010 - 02:32 AM

 The rules for creating a very large theater are not the same rules for creating a small home theater.  There are many reasons for this, but the basic is size.  There are many good sources for learning about this.  Check out books by Dr. Floyd Toole  and Tomlison Holman

Also checkout Dolby and THX websites for ideas on proper speaker placement.

#11 of 27 OFFLINE   Joseph DeMartino

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Posted April 21 2010 - 02:58 AM


Quote:
 But I'm justifiying experimenting with it as all theaters do it. 
 

But you don't have a theater.  You have a room in a house.  A couple of rows of theater seats do not a theater make.  Professional theaters spend tens of thousands of dollars or more to precisely tune the space to the function - using computer models, acoustic formulae, materials analysis and lots of other arcana.  Then they invest in heavy duty speakers and electronics that can move the vast amounts of air needed to create acceptable sound within their cavernous spaces.

No normal "home theater" is in any serious way analogous to these installations, and you cannot get similar results by trying to replicate their physical set up on a smaller scale.  There is a reason that the home theater industry doesn't offer this as a standard option.  Believe me, if it offered any actual advantage they would be shouting it from the rooftops and there would be enough folks with disposable income to buy it.  (And then the industry would try to convince the rest of us that we couldn't live without it, either.)


To borrow a line from Fran Liebowitz in another context, "Please realize that people have been cooking and eating for thousands of years.  So if you are really the first person to try adding fresh lime juice to scalloped potatoes, understand that there is a reason for this." 

Regards,

Joe



#12 of 27 OFFLINE   DanChristensen

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Posted April 21 2010 - 03:18 AM

 How did you join in December 1969 lol. Moderator. Okay yeah I wasn't sure what size it would take before it was a good idea. It's like 18 feet by 12 feet with a tall ceiling. Speaking of theater, how do they, with any amount of equipment, get the sound to be fairly good over the entire listening area? I don't care what tools and computers they have, the timing that all the sound would get to you in the corner would be sooooo far off from in the center of in the front. Is it, do they, time the speakers so the sound gets to the center at the same time creating the sweet spot or is it other wise? Surly acoustic treatment helps a lot to prevent it from being a cacaphonous mess in auditoriums, but. ....

You know what, I'm going to Tinseltown. All the theaters local to me have not great setups. I'm going to my hometown theater in Rochester to listen, and watch, they have stadium seating. I've been emailing them (202@cinemark.com) asking about sound systems and digital projectors. They said they STILL USE DOLBY 3 STEREO IN SOME AUDITORIUMS, and this is a NEW theater, it was built in the late 90s. 

I also ran into a guy working at a small local theater late at night while he was changing the sign and he said they had 5.1 setup, but it doesn't sound that great while your in there. They also have worse treatment; you can hear the movies playing next door (no not in other auditoriums. in other stores, it's located in a plaza). 


#13 of 27 OFFLINE   chuckg

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Posted April 21 2010 - 03:21 AM

The speaker arrays in movie theaters do indeed use delay, so that each set of surround channel is correctly timed to the fronts.  In a room that is 100 feet long, the delays are noticeable.  In a room 30 feet long, not so much.  The delays are so short, and the sound from each speaker roughly the same level, you'll get cancellations at all sorts of frequencies, and like somebody said, a muddy mess.  Also, the surround speakers in a large theater are somewhat more directional than those you'd use at home, so the people in row five don't even notice sound from the speakers for folks in row 35, which are very much farther away and lower in level.. 

But, feel free to experiment!  It's your stuff.  I myself have a pair of center speakers flanking the TV, because hearing the sound come from above the set bugged me.  Yes, when you sit off-axis the center channel doesn't seem to come quite from the center.  But, I sit dead center, and everybody else can just suffer.  :)

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#14 of 27 OFFLINE   David Willow

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Posted April 21 2010 - 05:09 AM

 Bottom line:  More does not equal better.

Large theaters make compromises so they can stay in business.  If they wanted the best sound, the room would be too small to make a profit.  Think about that.  Do you really want to replicate that thinking in your home theater?


#15 of 27 OFFLINE   John Garcia

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Posted April 21 2010 - 06:26 AM

Theater rooms are completely designed and treated to work with arrays of speakers and the seats/people are at different levels which actually aids in sound dispersion which is why it works in a theater.  IMO, it won't work in your living room unless you intend to treat it to a fairly decent level as well.

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#16 of 27 OFFLINE   Joseph DeMartino

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Posted April 21 2010 - 06:42 AM


Quote:
 How did you join in December 1969 lol.
 


I could tell you, but then I'd have to kill you.   On a more serious note, you have to realize that even in a large theater 80% to 90% of the sound in a typical film is coming from the front speakers, which are huge and placed directly behind the accoustically-transparent screen, and the subwoofers, which are largely non-directional, but placed so as to produce the best result.  The surround channels are used, just as they are in your home, to "fill in" certain effects.  The ones on the side-walls, in particular, don't necessarily have to have elaborate timing or be designed to produce "good sound everywhere", because they can be directional and only designed to produce "good sound" for the rows they cover, while not interfering with everything else.

But, again, unless you have an HT that is 100 feet deep by 70 feet wide and 30 or 40 feet tall, with seat on risers raked at around 40 degrees, you don't have anything like an actual theater.  Your side speakers likely will create sound problems, whereas the side speakers in that 100 feet deep theater with the stadium seating won't. 

It is your money, and you can certainly do whatever you like with it, but I suspect you're going to invest a lot of time and money in a system that will produce something markedly inferior to a standard 7.1 installation. 

Regards,

Joe

#17 of 27 OFFLINE   David Willow

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Posted April 21 2010 - 07:21 AM

 One final thought, then I'll shut up.  

I have found only 1 theater that even comes close to the sound I get from my moderately priced, non-dedicated home theater.  And that was a THX certified theater in Philadelphia - over 100 miles from me...  So trying to get the 'theater sound' is shooting too low, IMO.  


#18 of 27 OFFLINE   DanChristensen

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Posted April 21 2010 - 08:48 AM


Yeah, I know home cinema is usually intended to outperform commercial cinema, except in projector quality>where you don't even come close! /img/vbsmilies/htf/chatter.gif (arguments pursue).



#19 of 27 OFFLINE   Robert_J

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Posted April 21 2010 - 09:34 AM

I'll put my 4 (or it may be 5) year old 720p projector and DIY screen up against any of the local theaters that have a 16 year old projectionist.  I can easily match the quality.

I'm not sure about the status thing.  You can IM me technical questions all you want and I will ignore them.  Asking technical questions in that manner is a disservice to the community since IM's are not searchable.


#20 of 27 OFFLINE   DanChristensen

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Posted April 21 2010 - 09:43 AM

Well all I'm going by is my emailing to TInseltown 17 of Rochester who said they are going digital-so are my local theaters and he mentioned 4K projectors; and I product searched it and was like Holy crap I can buy a cinema 4K 2,160 line projector! and I showed him what one I was talking about (a sony SRX-S105 for 30,000) and he said that would be a joke to commercial cinema; that it would not be nearly bright enough.

HERE is what he said about it:

Daniel,
 
    The Sony SRX-S105 is a consumer grade piece of equipment and would in no way be suitable for commercial theater projection. It would provide neither the dynamic range nor brightness and overall quality to meet industry specifications. Theater grade equipment is not available for purchase by the general public, nor would many people be inclined to purchase it, given the 6 digit price tags generally associated with it. Significantly more than $30,000 anyways, and much larger in physical dimensions than that model. So it would be worse still to try and have 4 of these fridge sized devices crammed side by side attempting to accurately balance and align with each other. At the same time drawing a couple dozen kilowatts and putting out a significant amount of heat. Better to pay more upfront for a single projector solution than to have to pay more for electricity and the back-end infrastructure to support it all. It isn't as simple as cutting an image up into 4 parts and attempting to line the projectors up to each display that one image, not by far. This is an issue that has been looked into in the past. It is, quite frankly, more headache than it is worth. I would suggest, if you were willing to pay for it, an industry publication called the Large Format Examiner, which has in one of its back issues, a rather long and detailed article on why this only works for certain niche markets.
 
Brian
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