Home Theater Acoustics Help and Calibrating Your System:

Using measurements to optimize your home theater acoustics

Home theater acoustics are a problem most consumers are not aware of until it is too late.

A home theater is installed into an existing home and the builder, home owner, and installer are held captive by the room.

Why would this be a concern?

Home Theater Shack - Room EQ wizard

All rooms have what are called ‘room modes’.

A room mode is an area in the measured acoustic response that is amplified simply by the dimensions of the room itself.

In other words some notes will be much louder than others even if played at the same amplitude.

These modes are peaks and they CAN be calculated based on the dimensions of the room in question.

My room has peaks at 32 Hz, 48 Hz, and 67 Hz that are severe. I know- because I have measured them. These peaks are made even worse because there are nulls or voids in between them. So not only do I have peaks but also valleys in my room response.

Sadly, most home theater acoustics are this way. The intensity of the mode and valley is what makes a good room good, or a bad room bad. Meaning, some rooms have much higher peaks than others.

Of course, there are some things that can be done to help with these modes but I don’t want you to be mislead here. Some room modes are so strong fixing them completely is next to impossible. To get started on your Theater Plan and calculate room modes click here.

Start by making some Measurements – Home Theater Calibration test:

Master Handbook of Acoustics

To perform these tasks you will need a measurement software package or program such as Home Theater Shack- Room EQ wizard .

For the Master Handbook of Acoustics click this link.

1. Speaker and sub-woofer placement. Often, when placing a speaker where you want it, you end up with the worst response possible. Experiment by moving your speakers out into the room and apart while taking measurements at each location. Make notes of the locations and measurements taken. Finish by placing them in the place that sounds the best and has the lowest peaks and valleys. This is sometimes a compromise location between sound and measured response.

2. Room treatments can help to some extent but are only truly effective down to about 80 Hz. In order to effect very low frequencies the traps would be necessarily large. Much too large to place in a normal sized listening room. If taming extremely deep bass is what you need, forget about room treatments getting you there. You would need traps 6 feet thick to make an improvement to a 30Hz tone.

3. Build a Helmholtz resonator for your most problematic deep bass peaks. These can be built very inexpensive and they are effective in tuning a specific room mode/s mechanically. Understand that one resonator tube will only tame one specific room mode. You may need multiple units to tame your most obnoxious room mode peaks. More about the Helmholtz resonator here.

4. Use convolution software. This is basically the reverse of the measured response of your room.

Peaks and Valley’s are reversed and then stored as a wav. file. When music is played back it acts sort of like playing over a fingerprint. The output is reversed according to the measured response.

In theory this would work perfectly. However, in practice rooms are stubborn devices and it does not completely fix the response. It does help though.

5. The best alternative is to use a combination of all these methods.

Home Theater For dummies book

Use room treatments to help with modes from 200Hz and up.

Then use digital room correction for the response below 200Hz.

A Helmhotz resonator to tame the deepest problematic peaks.

The final performance of your Home theater response should be vastly superior to what you started out with.

To see more about the Home Theater for Dummies Book click here.

For more information of how to deal with home theater acoustics using the home theater PC – click here. To learn more about the home theater acoustics, the HTPC and even more that it can do. Read this article about crossovers.

• Read Part 2: Build Your Own Home Theater


Other Related Articles:

• Room EQ Wizard
• Home Theater Sound Proofing
• Go to: Best Home Theater Speakers
• Go to: Best Home Theater System
• Building a Home Theater PC

• Go to: the Best Speakers are DIY
• Go back to – Home Theater Plan and Acoustics
• Return to Home Speakers from: Home Theater Acoustics