For audiophiles, reading a good speaker review can activate the salivary glands. I don’t know if it’s because we like to live vicariously, imagining the experience of having equipment for too expensive for any rational man to own, or because we need some sort of validation on equipment we own. Whatever the real reasons may be, once the review is over, you’ll often be greeted by a series of graphs and charts.
Speaker companies, and most of the pro reviewers who do measurements, measure the response of speakers both on-axis and off-axis. Harman takes it to the extreme by measuring speakers on-axis, then off-axis in 10-degree increments in a 360-degree circle both horizontally and vertically. Often some of these measurements are combined to create an averaged response across a “listening window.” Past practice at S&V was to average the results at 0°, ±10°, ±20°, and ±30° horizontally. With the merger of S&V and Home Theater, this practice will be changing to the standard employed by Home Theater and sister publication Stereophile: an average of 0°, ±15° horizontally, and ±15° vertically.
Wait a minute! The measurements published for speakers are not the same averages? Two reputable audio publications measured things differently! Sound and Vision published averages for up to 30° off-axis and Stereophile measured only up to 15°.
Moreover, measuring the same speaker in an anechoic environment vs a quasi-anechoic environment (a half-million dollar facility vs. outdoors) produces startlingly different results.
Here, Brent measured one of the new Revel Performa F208. The former graph is in Harman’s anechoic chamber and the second is the quasi-anechoic environment of his back yard.
While there is some correlation between the two graphs, there are also some startling differences. And to even get those quasi-anechoic results, Brent had to do some seemingly extreme (and funny) setup as you see in the photo below:
The article goes on and is a great read for any audiophile. Nevertheless, the bottom line that I took away is to beware of any measurements posted online or in forums by so-called speaker ‘experts’. In fact, unless the methodology of how the measurements were taken is stated in the review I’ll be viewing them with some suspicion. I do want to tip my had to the publications (Stereophile and Sound and Vision included) that are part of the SoundStage network. They actually publish the speakers that they have measured in an anechoic chamber. You can see the list here and there is a link to the measurements of each speaker including the measurements at their various on and off-axis angles.
Thanks to Brent for putting together a great article. Now if someone could just tell me about those darn waterfall measurements 😉