http://JBL HOM Owner's Manual
• Target Curves:
Intuitive logic would tend to indicate that the best sound would be achieved when the system delivers flat frequency response. While this is true for all other components in the audio chain, this is definitely not true in the case of loudspeakers installed in listening rooms. There are several reasons for this, and it has taken many years of research to establish just what the most desirable performance characteristics are.
• Ideal Low-Frequency Response
Room boundaries (walls, ceiling and floor) tend to contain low-frequency energy within the room. Simply stated, this results in a boost in low-frequency energy. This is true whether it is a speaker or a piano producing the sound. The exact frequency at which this effect begins and the amount of boost realized are a function of the room size, shape and wall construction. No two spaces are ever exactly alike. This same low-frequency enhancement also occurs in recording studios, and the recording engineers know this will occur during playback. They balance their recordings in anticipation of this. Therefore, it would be wrong to “flatten” the speaker system response in the playback environment. To do so only results in a thin bass sound.
By surveying many listening rooms over the years, JBL engineers have established a low-frequency response characteristic that delivers the most consistently satisfactory results. This has been confirmed through extensive subjective evaluation tests.