DIY: Calibrate Your Speakers

I don’t know about you, but when I see a movie at the local multiplex, there’s an excellent chance that something will be wrong with the sound. Just as distracting as bad video (“Focus!!”), an improperly-calibrated sound system can seriously detract from the viewing experience. There’s nothing worse than explosions that physically hurt your ears or dialogue so soft you find yourself leaning forward to hear it. Thanks to the wonder that is home theater, you can now control what you’re watching, who’s watching with you, how it looks and even how it sounds. With the right receiver, an inexpensive sound meter and some audio test tones, you can fully customize every aspect of your audio system and make sure it’s optimized for your space and your ears.

Many new receivers, such as the Harman/Kardon AVR340 used here, feature automatic speaker calibration using a supplied microphone. HK calls this “EZ-Set” and their microphone conveniently plugs into the receiver’s front panel headphone jack. As with similar systems on other receivers, I recommend you use “EZ-Set” as a starting point, review the results, but then do your own test using a sound meter. For roughly the cost of two DVDs, a meter will ensure that your speakers are outputting equal volume and that your sub is providing the appropriate woof.

STEP 1: PREP & WIRING

Before you launch into on-screen displays (OSD) and crossover settings, make sure you have installed your speakers properly. Don’t play favorites with your speakers—treat them all as equals. That means use the same gauge (no thinner than size 16) of the same speaker wire for each of your main channels. (Different lengths are OK at these relatively short distances.) And keep your polarities straight—red to red and black to black. Your subwoofer should be happy with a single RCA-style subwoofer cable connected to your receiver’s line-level subwoofer output.

With everything connected, get out your receiver and DVD player remotes. Make sure you can navigate your receiver’s on-screen display and locate the relevant screens for speaker configuration. Find out exactly what can be adjusted and what your options are for each item. Consult the manual if necessary.

On the DVD remote, find the “A-B” or “loop” button and learn how it works. You’ll want to set up a short loop during the test tones for each of your channels. This will allow you to focus on reading the meter and give you plenty of time to make any necessary level adjustments. Finally, dig out the documentation on your speakers and research the “Frequency Response”—this will help you set the appropriate crossover point between the mains and the subwoofer.

STEP 2: SPEAKER SIZE & DISTANCE

Before adjusting the level for any of your speakers, you’ll first want to assign their correct size and distance using the receiver’s OSD. Receivers typically allow you to classify each channel (front, center, surround, surround back) as “Small” or “Large.” This is not referring to physical size but rather to bass capabilities. Speakers that qualify as “Large” are usually rather pricey and they have at least an 8-inch woofer with the ability to go below 40Hz. For most systems, and as a good rule of thumb, I recommend you stay fairly close to the official recommendations made by THX. THX suggests that you designate all speakers as “Small” and use an 80Hz crossover across the board.

“Delay” or “Distance” settings will help your receiver determine timing when it’s pumping sound out to your various channels. If your fronts are sixteen feet away but your surrounds are two feet away, many receivers can make minute adjustments so that output from these speakers reaches your ears at the proper time. Break out the tape measure and program your receiver accordingly.

STEP 3: SUBWOOFER & CROSSOVERS

Before going any further, we need to tell your receiver that you’re using a subwoofer. On the AVR340, this means changing the “Subwoofer” setting from “None” to “Sub.” Your choices for “Subwoofer” are often directly linked to what you choose for speaker size.

It should be noted that there is a difference between the Low Frequency Emissions (LFE) channel and ordinary bass in the main channels. When listening to a 5.1 digital soundtrack, “.1” refers to a dedicated LFE channel—pure bass—and its only destination is your subwoofer. However, your crossover frequency or “Low Pass Filter” is a (semi-flexible) wall that your receiver imposes on ordinary bass information existing in the main channels. For example, setting a crossover of 100Hz on your fronts will mean that in addition to your subwoofer getting everything in the LFE channel, the receiver is also going to send it everything below 100Hz in the front channels.

For test purposes, I’m using Definitive Technology’s exceptional ProCinema 1000 speaker system. The ProMonitor 1000 has a published frequency response of 47Hz to 30kHz. Since this speaker only has a single 5 ¼-inch bass/midrange driver, I’m going to set my fronts and rears as “Small,” use the THX-recommended crossover of 80Hz, and let my ProSub 1000 handle everything below that. As for the center, the ProCenter 2000 is very similar to the ProMonitor 1000 so it too will receive a “Small” designation and 80Hz crossover.

To avoid something called “cascading crossovers,” you should maximize the Low Pass/crossover setting (if there is one) on the back of your subwoofer—or disable it entirely if possible. Since your receiver is already handling the bass management duties, it’s best to remove the sub’s low pass filter from the equation so the two do not interfere with one another. For my ProSub 1000, this meant setting the low pass control at 150Hz—its highest setting.

STEP 4: ADJUSTING LEVEL: MAINS

Once you have correctly established speaker size, distance and crossover, it’s finally time to make some noise. That noise comes by way of irritating and loud (but necessary) test tones that will help you equalize the level/volume for each channel. There are several calibration discs on the market, including Digital Video Essentials which I used here. For our purposes, I used the 5.1 pink noise generator on Joe Kane’s heralded (but difficult to navigate) Digital Video Essentials DVD

Before starting the tones, make sure your receiver is set at a high reference volume and that it remains there. I like to use the 0dB setting, but whatever volume you choose, keep it constant for the duration of the test.

On your sound meter, your target for each channel should be 75dB. On an analog Radio Shack meter, you’ll want to set the Range dial to 70, put the Weighting on “C” and switch Response to “Slow.” Hold the meter slightly in front of you and tilted at an angle away from you—but don’t point it at any particular speaker.

Starting with the front left channel, adjust that speaker’s level via the receiver’s OSD until you’re reading a steady 75dB on your meter. If you have to adjust it more than 5 or 6dB, it might be easier to adjust your master volume until you have a 75dB reading and use that as your new volume reference point. With any luck, you’ll only have to tweak the remaining channels 1-to-4dB each to get them all reading 75dB. During these tests, remember to use the A-B loop function found on most DVD players; it will give you plenty of time to take readings and make adjustments.

STEP 5: ADJUSTING LEVEL: SUBWOOFER

The final channel you need to adjust is the subwoofer. Before you adjust the subwoofer’s level, check to see if your subwoofer has a phase control. Some subs have a Phase knob which governs whether or not the sub’s driver is moving in or out of synch with your main channels. Common settings are 0 or 180 degrees but some are continuously variable; experiment and find the setting that yields the maximum bass output.

As with the main channels, receivers have a level adjustment for the subwoofer. However, unlike the other speakers, there is also a “level” or “volume” knob on the subwoofer itself. Before starting the sub test tone, set the sub’s volume at 25 percent and drop the receiver’s sub level to its lowest setting (usually -10dB). This should start your sub at a low bass output and you can slowly bring up the receiver’s sub level until you reach 75dB. If your receiver’s sub level is at +10dB and the bass is still too low, bring it back down to -10dB, increase the sub’s volume knob to 40 or 50 percent and start the test again.

Unlike the other channels, the subwoofer test tone is not steady. It spans a wider range of frequencies and as a result your sound meter will jump around a bit. Try to find a level that keeps your subwoofer output hovering near 75 dB. For these readings, stand behind the sofa and move the meter from side to side in the primary seating area. Note the differences and try to take an average based on the different locations.

STEP 6: WRITE IT DOWN & TURN IT DOWN

When you’ve finished the calibration, go through each of the receiver menus that you tinkered with and write down the final values. This will save time in the event they ever get erased. Did you use an “EZ-Set”-type calibration first? How do the numbers compare? Remember to perform a full speaker calibration whenever you change your speakers, subwoofer, receiver or seating arrangement.

Finally, lower the volume! “0” or “reference volume” is extremely loud and probably much louder than you’d normally want for movie or TV viewing. Pop in your favorite audio reference disc or something that you’re very familiar with and start reaping the benefits of your newly-calibrated sound system.