# pressure waves in room



## Blaser (Aug 28, 2006)

I think I need to open the same thread here in order to have opinions of the acoustics masters about how well would bass traps help about the dips and the 5-6 db difference between ears.

http://www.hometheatershack.com/forums/home-audio-subwoofers/3737-pressure-waves-room.html

I would also like to know how much space I have to give up, and how much I would have to pay if possible.

Sorry for those who have already seen this thread at the home audio subwoofers section, but I thoughts I need the acoustics point of view not only the subwoofer performance....


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## bpape (Sep 14, 2006)

Can you post a sketch of your room please. SOMETHING is different left to right. Determining how best to deal with this in terms of sub/seating placement and treatments should be done after looking at what the room is potentially doing.

Bryan


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## Blaser (Aug 28, 2006)

Here is my room layout not to scale but close).

Pls note the following:

- WAF is 100%, I can do whatever is best for SQ, including replacing everything/removing things....anything.
- I am about to order dual RL-p18 will b in two 600 L boxes tuned 14-16 Hz, and they will be placed along the rear wall (behind TV), they will occupy about 70% of the width of the room and will be 1 m high. The cupboard will be sent out of the room as well as the old sub.
- The brown curve is unequalized, SPL meter placed at left ear
- The blue curve is uneqequalized, SPL meter placed at right ear
- Also note the cancellation above 70 Hz.

Thanks for helping....


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## Blaser (Aug 28, 2006)

Sorry, The FR above is the average one.

Here are the FR's I meant in the post above


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## Blaser (Aug 28, 2006)

OK forget about the problem at 45-55Hz, can anybody make a suggestion for the 70 to 85 hz large dip?


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## bpape (Sep 14, 2006)

Left corner is blocked by that china closet - right corner appears to be open. That's one difference left to right in the front that will change things.

Quite possibly, the dip could be from the distance from seat to rear wall if there's no significant absorbtion on the rear.

If you're going to put in 2 subs, you might want to try 1 dead center on the front wall and 1 dead center on the rear wall. That will help with some of the variations. Also try putting one up off the floor a foot or so.

Bryan


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## Blaser (Aug 28, 2006)

bpape said:


> Left corner is blocked by that china closet - right corner appears to be open. That's one difference left to right in the front that will change things.


That china closet will be thrown out of the room.


> Quite possibly, the dip could be from the distance from seat to rear wall if there's no significant absorbtion on the rear.
> If you're going to put in 2 subs, you might want to try 1 dead center on the front wall and 1 dead center on the rear wall.
> Bryan


I want to add corner traps in the front, a dead center on the rear wall is possible but probably not on the front wall.
Which products do you suggest?

Blaser


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## bpape (Sep 14, 2006)

Well, I recommend ours of course! :bigsmile: Seriously though something that's at least 4" thick for brodaband absorbtion down that low. 

If you can do one centered on the rear you'll just have to play with the front positioning to get it to blend right.

You might also consider shifting the entire setup (speakers and seating) say 6" to one side rather than sitting in the middle - that can also be a piece of the peak/dip issue.

Bryan


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## Blaser (Aug 28, 2006)

Sorry for being away that long.... I was building my subwoofers and it took all my time. Now that I completed my sub. upgrade project, I can now have more time and concentration on acoustics improvement.



bpape said:


> Well, I recommend ours of course! :bigsmile: Seriously though something that's at least 4" thick for brodaband absorbtion down that low.


Yes, I meant which models of yours?:bigsmile:

If you can do one centered on the rear you'll just have to play with the front positioning to get it to blend right.


> You might also consider shifting the entire setup (speakers and seating) say 6" to one side rather than sitting in the middle - that can also be a piece of the peak/dip issue.


Well that does not solve the problem. I have almost similar response laterally at LP (due to dual boxes).

Here is the new bass curve (blue is unequalized), of course I have removed the china closet:R
As well my new setup is attached.... I want to solve the cancellation problem I have between 40 and 70 Hz....Pls help!


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## bpape (Sep 14, 2006)

I'd likely start small with say 4 of the 244 panels. That's enough to do centered on the rear wall and directly beside the speakers to kill SBIR and reflections. Take a plot of what that does. 

Then, take the 2 from the sides and try straddling the rear corners of the room in addition to the ones centered on the rear wall.

In each of those cases, also try taking measurements with the mic about 6" forward and/or back from where you are now. 

Can you also please specifically identify:

- Length and width of the room.

- Location of the sub with regard to the length and width of the room.

- Location of your head with regard to length and width.

Bryan


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## thewire (Jun 28, 2007)

Check out the movie MY SUPER EX-GIRLFRIEND. This movie will benchmark your rooms response pretty well if your looking for a demo. The DVD is DTS btw.


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## Blaser (Aug 28, 2006)

LOL:R....Thanks Steven! I promiss I will...


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## Blaser (Aug 28, 2006)

bpape said:


> Can you also please specifically identify:
> 
> - Length and width of the room.
> 
> ...


Bryan,

Look above at a previous post and you will see my room layout and dimensions. Except the closet and subwoofers are bigger...


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