PSB’s “Special Sauce” Explained: In response to a question from a member of our group, Paul explained his thinking on what it takes to build loudspeakers that will work in the widest possible range of listening rooms.
In the real world, explained Barton, a major variable is the relative “liveness” or “deadness” of the speaker buyer’s listening room—something the speaker designer can’t possibly know in advance. According to Barton, almost any competently designed speaker that provided neutral or flat on-axis frequency response will work well in a dead (that is, very heavily damped) room, because the room will typically swallow up most of the speakers’ off-axis output no matter how good or how bad the off-axis response might be. But where the game becomes challenging is in trying to get speakers also to work well in relatively “live” or resonant rooms with lots of reflective surfaces. In those rooms, smooth off-axis response becomes critically important, because listeners will hear much of the speakers’ off-axis output reflected back toward their ears.
While noting that flat on-axis response is important, Barton emphasized that it is only a first step toward sonic excellence. The art of the design game, notes Barton, involves finding ways to make sure that off-axis response rolls off gradually and very evenly, so that there are no sharp off-axis response peaks or dips with which to contend (since such peaks or dips tend to stick out like the proverbial “sore thumb” in more lively rooms). To help ensure that PSB speakers work well both in “live” or “dead” rooms—or anything in between—Barton works very hard to optimize both the on and off-axis response of his speakers. And as you might have guessed by now, there are specific test regimens associated with this goal.
Although Paul did not have time to show us precisely how such tests are conducted, he explained that his standard practice is to measure all PSB speakers in 15-degree increments from the front side (from straight ahead, or 0 degrees, on around to 90 degrees off axis), both in horizontal and vertical axes. Then, he measures output from the rear of the speaker in 30-degree increments, again in horizontal and vertical axes. Barton keeps refining and adjusting his designs until he is satisfied that off-axis response is as smooth and evenly balanced as possible, yet without compromising smooth, flat on-axis response. This, says Barton, is the key to creating loudspeakers that will work well in most kinds of real-world rooms, a design practice we might describe as part of the “special sauce” behind the PSB brand.
In the second and final part of this blog, we’ll talk about the challenging and thoroughly eye-opening experience of participating in double blind listening tests in the NRC’s IEC-standard listening room. Until then, we wish you happy listening.