Possibly of interest. As I read this, he not only inveighs against *one* subwoofer but also against the idea that one should be satisfied with a monoaural effect from subwoofers.
From Jim Smith’s “Get Better Sound”
“One of the greatest disappointments for me has come from listening to stereo systems that incorporated subwoofers at shows and in home installations. I suppose it’s the complexity of getting so many variables correctly adjusted. This section is aimed at assisting you in improving this area if your system employs subwoofers.
Tip #31: Don’t believe the "experts" when they tell you that you only need one subwoofer
Low bass may be nondirectional, but the experts are dead wrong when they say you only need one good subwoofer. Unfortunately, while this "nondirectional" theory is based on some fact, the end result is far from correct. Especially for the playback of acoustic recordings.
No matter how great a single sub may be, a single sub kills acoustically recorded music. Over the years, we’ve proved this fact to many skeptics by playing acoustic recordings that contained no apparent bass at all! I guess I should say that multitrack studio recordings can also have some of the same qualities of an acoustic recording, but not always to the same degree. Here’s the reason why: Direct and reflected longwavelength, low frequency cues will arrive at each stereo microphone at slightly different times. Therefore, stereo subwoofers play these differing timearrival spatial cues in each channel.
Subwoofers provide the cues for a sense of space that can transform a system from simply sounding good to sounding uncannily real. This is accomplished because our ears decode spatial cues by picking up reflected sounds off of walls and ceilings. The time of arrival tells us how big the space may be.
Low frequencies have long wavelengths (meaning greater travel dis tances) and our brain decodes them as spatial cues. Acoustic recordings carry these low frequency spatial cues that are essential in our ability to suspend disbelief. This is how we hear and accept the illusion presented by recordings with a "we are there" perspective.
A virtual threedimensional image can be created, with each instrument or voice seemingly occupying a palpable space in the stereo sound stage in front of the listener. This is related to the earbrain low frequency, spatial cues.
When the bass is combined into one channel (as with a mono subwoofer), the differing time arrivals from each channel are simply canceled as outofphase information. A portion of the acoustic signature of the space is irretrievably lost. It no longer qualifies as a realistic recording of real instruments in a real space.
As a dramatic test of our theory, we’ve played our master recordings of handbell choirs recorded in a church or cathedral (predominantly high frequencies with some midrange and no apparent bass).
Sophisticated skeptics (an oxymoron?) are dumbfounded when they hear the ambient sound field collapse when we use one monaural woofer instead of a stereo pair. (Of course, the bass level was precisely adjusted to match that of two woofers when one woofer was played).
It’s important to note that the practice of using two subwoofers for home theater does not usually solve the problem for music. Although there are two subwoofers, they are both getting the same monaural signal from the A/V processor, so the stereo soundfield information on your CDs or LPs is still irretrievably lost.
In fact, increasing the mono bass channel to even more output than is required adds nothing to the acoustic signature of the space. As a highend designer, I typically wouldn’t install a single subwoofer in a music system due to its detrimental effect on the illusion.
Additionally, with two subwoofers, each sub has to work much less hard, dramatically reducing speaker cone movements (aka driver excur sions), resulting in lower bass distortion. But the primary advantage is more spatial cues with acoustic recordings (as opposed to studio mixed recordings).
Finally, locating a stereo pair of subs relatively close together is another recipe for less than the best reproduction. You don’t want them behav ing as if it was a stereotomono foldback in the bass, thereby essentially reducing the bass to mono. You’ll lose that wonderful spatial quality that properly placed stereo subs can provide.”
