TECH2

The CEA-2010 subwoofer output measurement lets us separate the great subwoofers from the merely good ones, in a way that’s more reliable and repeatable than traditional measurements or listening tests. However, it’s still not widely used. Sound & Vision and Audioholics are the only publications I know of that do CEA-2010, and I can name fewer than half a dozen manufacturers who do it.

I think one of the reasons CEA-2010 hasn’t caught on like it should is because most people—even most manufacturers—have only a sketchy understanding of it. Let’s fix that. In this article, I’ll explain how and why we do CEA-2010 measurements, and how to interpret them. You’ll even learn how to do them yourself with inexpensive gear.

Why CEA-2010?

The traditional lab measurement for evaluating subwoofers has been frequency response. It shows how even a subwoofer’s output is at different frequencies, and tells you the lowest and highest frequencies a subwoofer can reproduce.

I found out that frequency response provides an incomplete picture of subwoofer performance way back in the late 1990s, when I was conducting a blind test of subwoofers for Home Theater magazine. The test included a sub from Von Schweikert Research that according to my measurements had bass extension down to 19 Hz. Yet my listening panelists all thought that a B&W subwoofer, which had measured bass extension down to only 30 Hz, had better deep bass output.

I decided then to try to find a measurement that would correlate with my panelists’ results. I finally hit on something when I tried a crude distortion test, turning up each sub’s volume until it hit 10% total harmonic distortion at 20 Hz, recording the level, then repeating the test at 30 and 40 Hz. At the higher levels used for the distortion test, the B&W’s larger driver and enclosure produced much more output at 20 Hz than the Von Schweikert sub did.

To understand why, imagine you had a sealed-box subwoofer with a 12-inch woofer, with response that decreases by -12 dB/octave below 32 Hz. Well, why couldn’t you make it flat to 20 Hz by just hooking up a graphic equalizer and boosting the 20 Hz band by about +8 dB? You could, and at low levels, the frequency response measurement would tell you the sub’s flat to 20 Hz. But raise the level and one of two things will happen. The woofer might hit its maximum excursion (the maximum distance it can move forward or backward from its resting position). Or the amp might run out of power—no surprise, because that -12 dB/octave drop in bass response means it will take more than 6 times as much power to get the same volume at 20 Hz as at 32 Hz.

What is CEA-2010?

CEA-2010 is an industry standard first published in 2006 (updated as CEA-2010A in 2012) that specifies a method for measuring subwoofer output at different frequencies. The methodology was based on decades of research, and refined and codified by a panel of industry experts. The great thing is that it’s a standard, one that anyone willing to pony up $60 for the documentation can read and conform to. The results are meaningful because they can be compared to others’ results—unlike meaningless, made-up specs like “118 dB maximum output,” which don’t tell you anything because you have no idea how they were measured.