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Old 18th March 2007, 11:55 PM   #21
pjpoes is offline pjpoes  United States
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Ok I personally am not a fan of the colorations that horns have, and I think it makes movies sound funny. To me, I would rather accurate speakers over loud for theaters. However, you can have both, which was my point. Though Scanspeak is expensive, it will bring a ton to a home theater, besides being easy to design with, very accurate, but they play very loud with low distortion. This gives them great dynamics and makes them a great speaker for theater use. Yeah horns and general PA drivers will give you more efficiency, the use of larger drivers will give you more output with less drivers, but at the expense of accuracy and distortion. Some people can deal with that, I personally can't, I find I can hear those inaccuracies in the frequency response, and for me, it takes away from the experience.

Speaker designs like the Dunlavy's and any other sort of array method is great in that it allows ever increasing diaphram surface area where it matters most. I think Snell calls that expanding array technology, but I happen to agree that its a great method. If I had the room and money right now, my speakers would use a design somewhat like that, rather than either a simpler small design, or large horn loaded method.

Let me give another plug for going with surround sound. I don't think you will find the experience to be truely as involving. I first will say that the majority of center channels I have heard sound like crap and don't match well to the main speakers. The best solution I have heard is a speaker that is not only using the same drivers, but arrayed in the same orientation. I don't have that method in my own house, but I have an LCD and don't really have room for that. However, it would be my prefered method, and with a projector, the route I woudl take. Another positive of surround sound is that durring loud dynamic peaks, there really is no replacement for displacement. Having 5 speakers and a subwoofer, or two, will give you the ability to have that much more cone area for the peaks. Most movies, in my experience, take advantage of that fact and will have explosions and loud peaks run through at least the front three speakers somewhat evenly, if not all of the speakers. In a system with the main speakers setup as large, they also will take on bass for that channel, with LFE handled only by the sub, but none the less the dynamics are spread out mostly among all the speakers. In a smaller system with "small" main speakers, the sub will handle both LFE and the main speakers bass, in this case you need to have a sub that can keep up.

I think you are planning this anyway, but I recomend excessive subs. Example might be 4-15" woofers each getting 2-300 watts, ported box, etc. You could go with a horn loaded enclosure but you are going to lose some of the low end extension or have a very large box. This is an issue for movies as explosions have plenty of content between 40hz and 10hz. The tactile aspect of movies is going to mostly exist in the sub 30hz region. You can get output in excess of 130 decibles with a large ported box and plenty of cone area. Mach 5 has some very well priced drivers that will give you an arm up on this project as far as saving money. He also has a decently performing 6" midbass I believe you could use for your project.
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Old 20th March 2007, 07:08 AM   #22
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One cool thing about foam & concrete construction is that you can built the room in any shape you feel like.

Have you ever considered using non-parallel walls?

You would be the only guy on the block with a room like that, and there are acoustic reasons to do it too.

I've seen houses built like yours, those foam bricks fit together just like lego pieces! How cool is that?
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Old 20th March 2007, 07:10 PM   #23
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Hello JinMTVT,

You are getting some great advise here.

1) lose the square dimension of the room
2) wire for 7.1, even if you don't want to use it
3) use curved or off angle walls

Now for my thoughts

I agree with you about surround sound in that most of the systems are adjusted very poorly, but as many have said when done right the room you are in can disappear and you are transported to the place you see on screen. This can happen with a 2 channel system but it takes a lot more effort and $$$$.

I would put in a double wall up front and use the chamber for an Infanint Baffle line array using 4 FICaraudio Q.18's centered below the screen. With 2 feet between the walls you would have plenty of volume for the back wave. Check out this site, http://ibsubwoofers.proboards51.com/index.cgi

If you want a base horn just copy this installation, http://www.royaldevice.com/custom3.htm
He is getting 120dB at 1Watt 1Meter and 100dB 1W at listening area 6 meters away.
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Old 21st March 2007, 02:09 AM   #24
JinMTVT is offline JinMTVT  Canada
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I am more than aware that i am getting the best advices around here! that is the reason why i posted this here in the first place! so many wise users

Let's say that i am convinced that a properly designed surround system will transport me in another world.
I have to admit that, if the intent of the sound production was to use direct sound to overcome all reflections ( or the lack of it if treated properly? )
using drivers positionned all around aka 6-7.1 systems,
i guess that a real illusion could be created.

GM Greets!

I'm coming a little late to the 'party', but in a 'nutshell', the room dominates and you need as many channels (and speakers/channel) as required for the space to overload our internal processor (brain) into summing all the info it's being bombarded with. Anyway, spend the next week or three reading all the various Dolby papers, manuals, etc. if you're really serious about building a state-of-the-art mixing stage since that's what you ideally need to experience what the producer envisioned: http://www.dolby.com/resources/tech_library/index.cfm
i really like your approach and yes it does seem logical even to me ( humbly low brain life )
I have browsed through the dolby link you have provided without much success in securing some knowledge, could you point to a few "key" documents?

...no subs required...
sorry mate, i do not think that i will not use any subs
in my system ..probably will be completly overload with subs, isn't it the point to have too much of bass so i can tune down to just enough/perfect ??

So now i will look seriously at surround sound system since i do respect you all and you are pointing me toward something i seem to miss.

Then let's get working on surround sound stuff.
( sorry but i always need to understand 90%+ of stuff i do, otherwise i don't enjoy doing it )

What by definition is a complete surround sound system??

Then, what is with 6.1 and 7.1??
wich one should i focus on? cause i keep seeing mostly 5.1 movies, not 6.1 or 7.1
and then, what would be the implication of playing 5.1 movies on 6-7.1 system? and the contrary ?

Then for each driver position,
what are the requirements?

Is there any sub-bass sound included in the surround sound source ? rears? sides?
do i need as much sound power for the sides or rears as for the front loudspeakers?

i guess that using all the same drivers all round or timber match is really important?

I wanted to use diy dacs for each channel, this will be very complicated now ... should i settle for lesser quality receiver with built in sound splitter?
( i guess it would be easier to accept alot of different digital signals .. ) everything will be driven from a computer with coaxial digital output,
probably 90-95% movies

then about the room accoustics
I have read a few good books, ( notably MAster Handbook of Accoustics by McGRaw Hill ... )
so i understand most of the theories,
but applying it to real world stuff , i lack in experience.

so what are we looking for exactly ?
complete lack of reflection ?? partly?
I have almost no limitation in the form or size of the room, since my house plans will be changed accordingly.
I had originally planned non paralell side walls
and a size of approx 20' by 20' for the total room.

But i could make it a lot larger, and use curved walls also. the ceiling willl have to be striaght though as it is made of foam/metal joists on wich will be poured concrete so it needs to be perfectly straight
but i can add anything below it, could also make the room 9 or 10' high if needed.
I have also no aesthetic limitations ...
i don't watch movies with lights turn on

Was planned for 6 to 8 seats in 2 rows with the rera row beeing at 1.5' higher than the front.

So let me know what are your ideas for the room design

keep in mind that all the walls and ceiling will be in concrete covered with 2 to 4" of polystirene foam
( already really absoprtive ) and i plan to prototype a product i designed in my house that will replace drywall
( drysh$% ) and will be mostly foam and really absorptive also ... about 0.75" thick

thanks again all for your time
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Old 24th March 2007, 09:31 PM   #25
JinMTVT is offline JinMTVT  Canada
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Join Date: Jul 2004
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C'mon guys!
i need some input soon ...

i will need to complete my house plans in the next 1-2 months now , and judging from the influence you guys have on me for this theater room

i will probably have to relocate a few unimportant rooms
( wife's stuff ... )
and drastically change its shape!
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