For today's How-To you'll need:
- Surround sound system
- SPL(Sound Pressure Level) Meter
- Test tones
Sorry guys, we're not going to get into deep discussions of speaker arrangements. Speaker placement depends on your speakers and the materials and acoustincs in room you're using. Your receiver should have included some specifications, but if you need some fresh guidance, check out the Dolby layouts
and THX placement
guides and decide what works for you.
The human ear is subjective. Everyone hears things just a little differently. Trying to set sound levels by ear is similar to trying to compare two weights by holding one in each hand. You can make a reasonable estimate, but you probably won't be all that accurate. (Think Indiana Jones and Raiders of the Lost Ark.[Update: Will needs more sleep])
To give us a consistent measurement, we need a mechanical ear. A quick trip to Radio Shack (Part# 33-4050) netted us this handy analog sound meter for about $50. It will give us a consistent frame of reference for measuring sound levels. Don't forget to grab the thoughtfully not included
battery. The analog is a bit cheaper than the digital version, and is generally held in higher regard than its digital counterpart -- gasp!
To tune up the system, we'll play a set of sounds through one speaker at a time. From the listening position, we'll measure the sound level from each individual speaker. In order to get a true calibration, it's better to play test tones from your DVD player rather than the built-in tones that your receiver produces.
If you picked up the Avia DVD from the front projection How-To, it contains audio test tones as well as speaker phase tests under the Advanced section of the disc.
The C setting tells the meter to measure the entire sound spectrum. Setting the response to SLOW will probably be easier to deal with. On fast, the needle might get a little crazy. Cue up some test tones and set the volume on your system to a comfortable level. Have a seat in your ideal move watching position. Now adjust the turn wheel on the meter so that the needle is somewhere in the middle of the gauge. (At 60, the 0 on the meter represents 60dB and so on.) If it makes it easier, you can tweak the volume a bit to center up the needle. From this point forward, don't touch the main system volume at all.
Unfortunately we have to do a little bit of math when it comes to measuring sound levels below 500Hz. When measuring the sound levels from a subwoofer, the meter will read on the low side. The guys over at the AVSforum
have used some high end tools to compare the results and suggest that with the Avia DVD, the meter will read low by about 2-3dB. The discussion was around the older meter, but it should be applicable.
To dial in the settings, you'll probably need the original remote. Ours allows quick access to the test tones, individual channel selection and level controls. Some receivers use software menus to access these controls. If you're not sure how to get there, google up an owners manual for your receiver.
As you cycle through each channel, you should be able to adjust each channel's volume. Some models may not let you adjust one channel. Make sure you start with that one as the control channel (what you compare everything else against).
Now it's time to bring all the pieces together. Sit down in your ideal listening location: couch, loveseat, whatever it is your speakers are aligned around.
- Put on your test tones either using a test CD/DVD like Avia or just the built in tones on your receiver.
- Reset the adjustment on each individual channel to 0.
- Set your volume to your listening level if you didn't already.
- Dial your meter in so that the needle is fairly centered.
- Using your center channel as your control volume, note the location of the needle on the SPL meter.
- Adjust each channels volume level so that the needle is in the same position as for the center channel (except the sub-woofer).
- Add 2 to 3dB from the needle's position and adjust the sub-woofer levels.
- Kick back Peter Murphy style.
That's it for our simple How-To on dialing in your surround sound system. Now it's time to start churning through the action section on Netflix and try this sucker out out. Don't be afraid to adjust your sound levels once you set them up. Even with all of today's sound standards, everything is mixed differently according to the sound tech and director's tastes. Enjoy!