# Size of room question



## louie2814 (Jun 25, 2014)

Hi all. I have a basic question about how to right size what I will buy for a 5.1. Here's my layout. 

http://i.imgur.com/nAiXjX9.jpg
http://imgur.com/TY1TAIR

My question is...the projector viewing area is an area about 150 sq feet. This is one side of a basement that is much larger. The other side has a bar and a pool table. When trying to buy my speakers and sub, should I consider specifically the area that will be the main seating area or is the size of the whole room more of a concern based on sound acoustics?

I just want to make sure im buying the right subwoofer first and foremost


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## Lumen (May 17, 2014)

The whole room (both size and shape) will affect how your speakers and sub sound. The sub should have enough power to fill the entire space (unless you plan to position it nearfield, which is almost never the case. Multiple subs will help smooth out the response so that all seating locations get the same quality bass.


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## AudiocRaver (Jun 6, 2012)

Lumen said:


> The whole room (both size and shape) will affect how your speakers and sub sound. The sub should have enough power to fill the entire space (unless you plan to position it nearfield, which is almost never the case. Multiple subs will help smooth out the response so that all seating locations get the same quality bass.


I agree with Lumen.

Another thought, though... You would like to get soundstage and imaging (SS&I) that _sounds_ symmetrical while your room is anything but symmetrical. The best way to do this is with speakers that have controlled directivity at mid- and high-frequencies. A well designed horn tweeter can accomplish this, like the Power Sound Audio MTM-210 or the PreSonus Sceptre S8 (I will be posting a review of them in a day or two) for medium- to small-sized home theaters. Speakers of this type can do a pretty good job of "erasing" room asymmetry.


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## Lumen (May 17, 2014)

AudiocRaver said:


> I agree with Lumen.
> 
> Another thought, though... You would like to get soundstage and imaging (SS&I) that _sounds_ symmetrical while your room is anything but symmetrical. The best way to do this is with speakers that have controlled directivity at mid- and high-frequencies. A well designed horn tweeter can accomplish this ... Speakers of this type can do a pretty good job of "erasing" room asymmetry.


Thank for sharing that, Wayne. Nowhere in any of the threads about converting great rooms to HT's have I come across this simple, yet effective solution. Most often, I've read advice like "play along the diagonal," or "switch from short wall to long wall." I myself have always suggested "building or using a fake partition or wall" to force symmetry. Never occurred to me to change speaker types! Excellent tool to add to our bag of tricks!


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## tonyvdb (Sep 5, 2007)

For the lower frequencies the entire space even the upstairs must be included if there is no door to close off the space. Bass frequencies need to pressurize the room and if it is open to other areas that must be included in calculations for how big a sub or subs you get.


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## prerich (Mar 26, 2008)

Lumen said:


> The whole room (both size and shape) will affect how your speakers and sub sound. The sub should have enough power to fill the entire space (unless you plan to position it nearfield, which is almost never the case. Multiple subs will help smooth out the response so that all seating locations get the same quality bass.


Agreed!!! The OP looks like he has a lot of room to fill! I would definitely opt for multiple subs in this enviornement!


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## prerich (Mar 26, 2008)

AudiocRaver said:


> I agree with Lumen.
> 
> Another thought, though... You would like to get soundstage and imaging (SS&I) that _sounds_ symmetrical while your room is anything but symmetrical. The best way to do this is with speakers that have controlled directivity at mid- and high-frequencies. A well designed horn tweeter can accomplish this, like the Power Sound Audio MTM-210 or the PreSonus Sceptre S8 (I will be posting a review of them in a day or two) for medium- to small-sized home theaters. Speakers of this type can do a pretty good job of "erasing" room asymmetry.


Good post, as usually - AudiocRaver!!!! Could the Reaction Audio CX-10's be taken into consideration for this project? Although they are not horns - they are coaxial mounted speakers that also have controlled directivity, and time aligned. Your speaker recommendations are great as well!!!


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## AudiocRaver (Jun 6, 2012)

prerich said:


> Good post, as usually - AudiocRaver!!!! Could the Reaction Audio CX-10's be taken into consideration for this project? Although they are not horns - they are coaxial mounted speakers that also have controlled directivity, and time aligned. Your speaker recommendations are great as well!!!


Yes, the CX-10 could be an excellent candidate as well. The concentric-driver high-efficiency design approach holds much promise for Home Theater applications. Would love to hear a pair (or five) of them!

Two questions that would only be answered by auditioning/measuring:

How "directive" are they?
Does the tweeter have any "stored energy" issues? This is one I have been especially on the lookout for recently - ribbons and electrostatics and AMT tweeters are pretty much immune, dome and compression tweeters can go either way depending on design.


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## dgmartin (Oct 29, 2011)

AudiocRaver said:


> Yes, the CX-10 could be an excellent candidate as well. The concentric-driver high-efficiency design approach holds much promise for Home Theater applications. Would love to hear a pair (or five) of them!
> 
> Two questions that would only be answered by auditioning/measuring:
> 
> ...


Interesting designs mentioned above. They are certainly a step in the right direction to minimize the early reflections. A strong toe-in also helps. I would wait for measurements before purchasing those models without a chance to listen. 

AudiocRaver, any particular reason you measured the S8 at 1/4 meter in this particular review?


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## Lumen (May 17, 2014)

tonyvdb said:


> For the lower frequencies the entire space even the upstairs must be included if there is no door to close off the space. Bass frequencies need to pressurize the room and if it is open to other areas that must be included in calculations for how big a sub or subs you get.


Oh just great, more math! 
On the serious side: Good point, Tony. Cubic volume rather than square footage needs to be considered. I wasn't aware there were equations/calculators for that. Time for a little :reading:


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## AudiocRaver (Jun 6, 2012)

dgmartin said:


> AudiocRaver, any particular reason you measured the S8 at 1/4 meter in this particular review?


i was simply looking for a measurement that was representative of the S8 performance and was free of disruptions from reflections. I took measurements at the LP, at 1 m , at 1/2 m, and at 1/4 m, and all of them showed the same information, but only the 1/4 m plots were free of reflections.


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## dgmartin (Oct 29, 2011)

AudiocRaver said:


> i was simply looking for a measurement that was representative of the S8 performance and was free of disruptions from reflections. I took measurements at the LP, at 1 m , at 1/2 m, and at 1/4 m, and all of them showed the same information, but only the 1/4 m plots were free of reflections.


OK I see you used gated measurements only for the off-axis angles. I was curious to see if on-axis is consistent with distance given the unconventional arrangement. Thank for your reply.

@Lumen:
The calculation is simply based on change of volume caused by the driver. For instance, check
www.cartchunk.org/audiotopics/SmallEnclBass.pdf. I did not open a textbook to check if all constants are correct but it gives the idea.


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