What is the fundamental secret of the world of audio? Every time you change a piece of equipment, two distinct and significant changes occur in your sound. The first change relates to the inherent sonic differences between the two devices themselves. The second change relates to how each device alters the interaction between the loudspeakers and the room; essentially, each piece of equipment shifts the perceived position of the speakers, which in turn changes the sound. This is why Sterling argues that even after a minor change to a system, the loudspeaker positioning must be readjusted. This realization implies that all the A/B tests you have previously conducted—whether comparing two DACs, cables, or any other components—need to be re-evaluated from scratch. Failing to grasp this point often leads us to spend years focusing exclusively on swapping and upgrading equipment, ultimately leaving us trapped in a vicious cycle.
I have two experiences from the past that relate to the importance of speaker placement, as well as two recent experiences involving A/B testing with speakers in different positions.
My first two experiences date back to 2005 and 2009, when, purely by chance, the loudspeakers ended up in a good position. The sound turned out excellent; in 2005, I didn't realize that the speaker placement was the reason for the great sound, but by 2009, I understood that the positioning was indeed the cause. As a result, I spent a significant amount of time researching online until I came across an article on "DPOLS" by A. Polakov, which I discovered via the following link:
http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=3&postID=29861
Very little information has been written on this subject. Because the concept itself seems so strange and implausible, it is almost never discussed; consequently, for years, the most valuable and critical parameter of sound has remained hidden from everyone.
Two other experiences I’ve had over the past five years have led me to realize that all the tests we conduct—listening to and comparing two devices, two cables, or anything else (an "A vs. B" comparison)—are directly influenced by the placement of the loudspeakers. This makes it impossible to gain a complete and profound understanding of the true differences between A and B. Why is this the case? Consider this: when you swap cables and listen to the sound produced by Cable A versus Cable B, each cable exerts a different influence on the time-domain response—or, more specifically, the phase-frequency response. This variation in the phase-frequency response propagates to the loudspeakers and the room, altering the entire acoustic equation; the resulting interaction between the speakers and the room could be either positive or negative. A listener cannot easily isolate this effect from the inherent characteristics of the equipment itself, and this is precisely where errors in judgment can occur.
I have made this mistake twice in the last five years. The first instance occurred one night when the sound quality wasn't good; we tested a much cheaper DAC and found that the sound improved significantly. This test led to the impression that the inexpensive DAC offered superior sound quality. The difference was so stark that even I was surprised. Later, I realized that the reason for this difference was that, given their specific placement, the speakers simply performed much better when paired with that cheaper DAC. My second mistake happened when we attempted to compare two discs—a 16-bit CD and a 24-bit DVD—using two different transports.
In our initial test, 24-bit audio sounded significantly better than 16-bit audio; we repeated the test using several different transports, but the result remained the same. We concluded that a 24-bit/96kHz disc offered vastly superior sound quality compared to a 16-bit/44kHz disc. This conclusion turned out to be completely wrong, however—some time later, I moved the speakers and we reran the test. It was unbelievable: this time, the 16-bit CD sounded far better than the 24-bit DVD. It was the strangest experience I’ve had in 25 years, but the reality was that the placement of the speakers had completely upended all our calculations for the A/B test.
If you intend to compare A with B, first adjust the speakers for A and listen to the sound; then, when you bring in B, you must readjust the speakers for B before listening and making the comparison.
www.amiraudio.com, www.hifi.ir