Measuring Loudspeakers, Part Three Page 9
Vance Dickason  offers some discussion of this question, but the definitive answers are to be found in Floyd Toole's comprehensive 1986 papers [78, 79]. Nothing that I can conclude from my past eight years' work, at least when it comes to conventional forward-firing, moving-coil designs, is in serious conflict with his findings. As I wrote in 1991 , "The best-sounding loudspeakers, in my opinion, combine a flat on-axis midrange and treble with an absence of resonant colorations, a well-controlled high-frequency dispersion, excellent imaging precision, an optimally tuned bass, and also play loud and clean without obtrusive compression."
While each measurement of a specific area of loudspeaker performance gives important information regarding possible sound behavior, it emerges that there is no direct mapping between any specific area of measured performance and any specific subjective attribute. As a result:
• Any sound quality attribute always depends on more than one measurement.
• No one measurement tells the whole story about a speaker's sound quality.
• Measuring the performance of a loudspeaker involves subjective choices.
• All measurements tell lies.
• Most important, while measurements can tell you how a loudspeaker sounds, they can't tell you how good it is. If you carefully look at a complete set of measurements, you can actually work out a reasonably accurate prediction of how a loudspeaker will sound. However, the measured performance will not tell you if it's a good speaker or a great speaker, or if it's a good speaker or a rather boring-sounding speaker. To assess quality, the educated ear is still the only reliable judge.
And no matter how good any one measurement, if the beginning of the third movement of Beethoven's Fifth Symphony, where the composer introduces the trombones for the first time, or Jimi Hendrix's hammered-on tremolo at the start of "Voodoo Chile" on Electric Ladyland, doesn't send shivers down your spine, the loudspeaker is still doing something, somewhere, wrong.
Acknowledgments: When it comes to measuring loudspeakers, the following individuals have all freely shared their knowledge, experience, and opinions: Larry Archibald, Graham Bank, Paul Barton, John Bau, Martin Colloms, John Crabbe, John Dunlavy, Malcolm Omar Hawksford, Ken Hecht, J. Gordon Holt, David Inman, Ken Kantor, Don Keele, Thomas J. Norton, Wes Phillips, Doug Rife, David Smith, Bob Stuart, Jim Thiel, Kevin Voecks, and Peter Walker. Any errors, misunderstandings, or misstatements in this paper are my own. I would also like to take the opportunity to thank Martin Colloms and the late James Moir for allowing me to take part in many, many single-blind loudspeaker listening tests from 1977 though 1985. The experience was an education in how to assess the sound of a loudspeaker by listening to it.