How good is your home theater plan?
Are room acoustics an important part of your plan? Fact: “Room acoustics have more effect on the sound quality than any electronic component in your system.”Yet the room is usually the most ignored subject…
Before you begin theater room construction do an acoustics assessment.
What Kind of home theater project are you working on?
Considering a complete build from the ground up or just modifying an existing room?
To avoid any surprises make sure to clearly define your home theater setup and Home Theater Room Design.
Room dimensions and Home Theater Layout are important factors of a home theater plan and will affect the audio performance of any room.
Even a room that has been carefully planned out and well engineered would benefit from the use of these proven methods to tame the room response.
No room is perfect! But there are many methods that anyone can use to prepare for a very finehome audio design.
For basic acoustics reading try the; Home Theater for Dummies book.
A. Address the room dimensions: Sometimes in very large rooms you can add a false wall to improve the acoustics. Generally, the closer your room is to square your room modes will be higher in level. And deeper valleys between the peaks.
These will likely be your worst room modes. We suggest you follow this up by taking some actual room acoustics measurements and audio home speaker testing (in-room response measurements).
To learn more about the book Master Handbook of Acoustics click here.
You will need to know which room modes need to be corrected first. Here is the link:
http://www.mcsquared.com/modecalc.htm Room Mode Calculator to help access your Home Theater room Design problems.
You will also need to take acoustical measurements of the response in your room. Use Room EQ wizard software to take these in room measurements.
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What to do after making your Home Theater Room Acoustics measurements:
1. Work on taming the upper bass and treble frequencies in the home theater plan first. Placing absorbing acoustic panels may have a small influence on the low and mid-bass as well.
It is a good idea to dampen first reflection points prior to doing anything else. This will lessen echo in your room and make the rest of your home theater plan easier to finish.
2. Locate these points by sitting in the sweet spot or main listening location and have a helper walk with a mirror flat against the side walls.
You will see your speaker in the mirror and place a piece of tape for that reflection point. You will have two of these for each side wall and back wall. There will also be two first reflection points on the ceiling as well. Some place a sound panel there, some don’t. Use your own discretion.
a. Use thick sound panels at the first reflection points. If making the traps DIY use 2×4 lumber and a bat of Owens corning fiberglass within. These traps are very easy to make. Stretch a tough fabric like cotton canvas over the 2×4 frame that will match the décor of the theater and home theater plan. This fabric can be found at nearly any fabric supply store.
b. Place a set of these traps into the corners of your room if possible. Corners are a problem area for all rooms. Pressure builds up between the two walls. A good way to test this is to play music and walk into a corner. You will notice a higher pressure level within the corner.
3. Employ the use of a Helmholtz Resonator or Absorber. This mechanical device will essentially act in reverse to the way a port works in a loudspeaker.c. Your room may have some very strong peaks and deep valleys – you will want to tame these as there can be adverse effects in other parts of the range. In other words correcting mode A may affect mode B. So take steps to correct the worst modes, re-measure the response and correct again. It is likely that only the two or three worst modes are responsible for making a room sound ‘annoying or un-listenable.
This type of resonator uses your room like it is a speaker driver and reverse pressurizes the room at the given frequency at which it is tuned. Because of this it only works within a very specific range of Hz or cycles, just like a speaker port. This is a good thing! If the resonator would pull down the response across a broad range it would lower the total bass output of your bass speaker. Not good!
The Helmholtz resonator will NOT look like the picture to the right. This is a picture of the original invention of Helmholtz himself. An in room application will look like nothing more than a cylinder – probably sitting upright in the corner of your room.
a. You may have already figured out that to tame 3 different modes you would need 3 different Helmholtz resonators.
- You would be correct. The good news is that they are very easy to build.
BUT, the Helmholtz resonator MUST be built very precisely or you may affect the wrong frequency within your room. This mistake could make your room response even worse. If you tame a valley instead of a peak you will compound the problem in the home theater plan.
b. Here is the calculator for the Helmholtz resonator to help you with your home theater plan. The Helmholz resonator formula is found here…
We apologize the Helmholtz box calculator has been taken down. This was an affiliate link and they are no longer servicing their site.
I apologize it is in centimeters. You can convert the measurements to inches when you have the dimensions for your enclosure. Also I have heard that it is better to use a cylinder shape such as a concrete form. Just convert the interior volume to a cylinder.
Here is the formula: fo = 2160*sqrt(r/((d*1.2*D)*(r+w)))
Summary for Installing a Home Theater and Home Theater Setup:
Finding the best locations for your absorber panels and Helmholtz resonators for a good home theater layout may take a bit of trial and error. Place some traps and resonators into the corners first. Then place absorber panels at the first reflection points. Measure the room response and adjust the traps, then repeat by moving the traps to different locations and measuring again. Repeat these tasks until you are satisfied that the results you have are the best you can achieve.
After completing a home theater plan and acoustic treatments you have one more option available. This last option will take a bit more work but will look much more professional.
This approach is often used where you see a fabric covering the walls of a home theater.
It is possible to build some of these Home Theater Acoustic traps into your room by ripping off the drywall and placing the insulation between the studs. If these are exterior walls make sure to seal off the inside of the cavity with a vapor barrier.
Prior to covering with fabric ensure that there are no air leaks allowing air to get inside the house. Then cover the fiberglass with the same fabric as used for the acoustic traps. If this is a new theater build just build these into the walls from the very beginning. Cover them with a nice fabric that will complement the decor’ of your room.
Other Related Home Theater Plan Subjects:
• Home Theater Sound Proofing
• Home Theater Acoustics – Go to Home Theater Layout
• Go to: Home Theater Curtains
• Go toTheater Setup Basics: from Theater Plan
• Return to Home Speaker from: Home Theater Plan
• Audio file home system theater (audiophile)