# Acoustics for H.T. Room



## jackboy (Aug 14, 2011)

What is the best gear to treat my room it is 7m X 5m X 2.4m it has carpet and curtains on the two windows as well when I built the house the builder put sound check dry wall on only one internal wall.


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## GranteedEV (Aug 8, 2010)

*Re: Room treatments*

Thick broadband bass traps are probably going to make the most notable difference. You can probably make your own with some of this:

http://www.atsacoustics.com/item--Roxul-Rockboard-60-Case-of-6--RB60.html

One case per 12" thick trap. Try to cover from floor to ceilign where possible, and corners are a great place to start.

Additionally, I would consider carefully placed diffusion panels to hopefully enhance spatiousness. GIK Acoustics makes some. Place them on the ceiling and rear wall for starters.

Whether to treat immediate reflection points or not, is a matter of your speaker's off axis behavior and your own indifividual preferences. Lesser speaker designs benefit most from such treatments.

Playing around with speaker and seating placement and orientation can also make a notable difference. More details would be appreciated as to your setup.


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## SAC (Dec 3, 2009)

I would be remiss in simply trying to provide specific treatment recommendations based upon generalized napkin analysis, as they might work, or depending upon room specifics, they might not.

A general approach can be stated as bass traps to control room modes and absorption/diffusion to control specular reflections within the room, but that being said, the devil is in the details.

What allows one to move from the realm of generic treatment notions to that of room specific treatment options is actually not that difficult.

Ignoring isolation issues for now (as this is a topic that deserves more attention than is possible in this response both with regards to the how-to's as well as the basic approach!')...and assuming you are 'stuck with the speakers you currently have - as speaker Q and controlled dispersion is a subject too often overlooked in selecting speakers for use in the room!

First, you use a tools such as REW to properly general waterfall plots to determine both the modal composition of the room, as well as the modal distribution within the room.

Then you should properly generate ETC responses for each speaker.

The next IMPORTANT step is to determine the acoustical room response model that you wish to achieve as well as what is practical, in the space! This is critical, as this will provide you with the goal and roadmap that will determine what you do as far as treatment! (Again, this is a broad subject with many options that is a bit beyond the scope of this thread. But suffice it to be said that there are a few rather nifty strategies that can be applied here that can make the overall process much easier!). 

Then, with the test results, and a defined goal in mind, one can then determine the type of modal treatment to be used (porous velocity based absorbers or tuned pressure based resonators) and with the modal mapping and symmetry determine optimal seating locations as well as the types and locations for the LF modal treatment. (Note, this may also involve moving and optimizing the speaker locations as well due to SBIR, etc....

Once that is achieved, the ETC responses can be used to identify anomalous reflections (as not all reflections are necessarily bad!), and then to resolve each offensive reflection into their specific paths; and then to select the proper treatment per each reflection arrival time and gain that will contribute to the acoustical response model desired - be it absorption or redirection and diffusion.

Then measurements are repeated as necessary to insure that the desired results are actually achieved.

This may sound complex, but it is actually not. In fact, knowing exactly what is ACTUALLY happening and then surgically treating the real problems greatly increases the quality of the resulting room while reducing complexity of the overall task (as well as avoiding creating additional problems - including that all too common problem of an overly damped (dead) room!). Additionally, one will generally save money and time by using only the type and mount of treatment actually needed.

This process can be applied successfully to any room.


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## jackboy (Aug 14, 2011)

Thanks for the info. What equipment do I need to do this test I have a laptop and can download the software.


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## SAC (Dec 3, 2009)

jackboy said:


> Thanks for the info. What equipment do I need to do this test I have a laptop and can download the software.


A properly configured PC with RoomEQWizard (REW), a suitable mic pre-amp and an omni mic.

Use of the the loopback hardware propagation delay calibration is necessary. Here is a simple pictorial description of the physical configuration for loopback.
No need to worry about gain or mic calibration.


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## jackboy (Aug 14, 2011)

Can you hire this set up or should I get someone in to do this for me.


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## SAC (Dec 3, 2009)

Have you read any of the REW product information, the user's guides to set up, or the support site here on the forum?

It essentially involves installing the software application, attaching and configuring the IO pre-amp most generally to the USB or Firewire port, attaching an appropriate microphone, and then following some simple procedures.

A relatively simple procedure...

And if you encounter difficulty or confusion, post in the REW support section and folks can help. 
Its not difficult! And help is available.

Its not much more difficult than attaching and configuring a printer or scanner.
I am confident that you can do it!

Why all the hesitancy, and apparent (to use a bit of hyperbole) 'fear and trepidation'?onder:


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## bpape (Sep 14, 2006)

A couple of other pieces of information would be valuable.

What is the room used for? Purely HT? Any 2 channel listening? If so, which do you want to optimize for? How many seats and people in the room?

Any chance of a rough top view sketch of the room so we can better see where is available for treatment?

There are some things that will be required regardless - broadband bass control, addressing early reflections, etc. Just a matter of how much, where, and as SAC said, a hint of the response of the room to see what other specific things need to be addressed.

REW isn't hard to use. There are some excellent tutorials on this site.

Bryan


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## jackboy (Aug 14, 2011)

I will try and put a lay out of the room and it's only for movies.


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## jackboy (Aug 14, 2011)

Here is a lay-out of my room it has carpet only the internal wall has sound check gyprock there are 6 theater chairs.
Also the windows have large block out curtains
The first row of sets are about 5m for the speaker and the back row is about 6.5m back
as this is my first set up I did not know what i was doing. I am not sure if i placed the rear speakers in the right place. I hope i am able to upload this lay-out so you can help me out.
The ceiling height is 8ft.


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## jackboy (Aug 14, 2011)

I don't know how to upload my photos:hissyfit: http://www.hometheatershack.com/forums/images/smilies/hissyfit.gif


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