Positioning Subwoofers - Community VERIS 2 Operation Manual

The smallest subwoofer, the VERIS 2-210S, is characterized by an exceptionally tight and
punchy sound. The larger VERIS 2-212S adds a deeper low end, but still with a very rapid
transient response. The new VERIS 2-215S remains capable of clean and responsive bass
reproduction, but with greater power and depth than its smaller siblings.
When using multiple subwoofers, such as two or three on each side of a stage, it's best to
keep the enclosures stacked or positioned tightly together for the befit of maximum mutual
coupling.
If an external electronic crossover is employed, the use of a subwoofer will free up the low-
frequency power demand of the full-range loudspeaker(s), thereby increasing output capability
in the upper bass range. An electronic crossover will also reduce intermodulation distortion in
the amplifiers, resulting in much improved sonic performance.
Note: The guidelines referred to above are "rules of thumb only." Performance will
vary based on room acoustics, room geometry (particularly ceiling height), the
location of the loudspeaker(s), the size and type of the amplifiers, and the stylistic
demands of the music and speech that are to be reproduced.

POSITIONING SUBWOOFERS

Subwoofers are far less directional than the mid-range and high-frequency loudspeakers they
are designed to augment. This is because low-frequency wavelengths are significantly longer
than mid-range and high-frequency wavelengths. A 30 Hz wave is approximately 35 feet in
length and a 100 Hz wave is approximately 11.3 feet in length. These extremely long
wavelengths cause behavior that's quite different from their shorter mid and high-frequency
counterparts.
First, long wavelengths do not 'see' small or moderate size obstructions as obstacles; they
simply diffract around such barriers, as if they're not there.
Second, the substantial length of low-frequency waves can make it difficult to distinguish their
source direction. This is why a single subwoofer can often be used successfully to augment a
stereo pair of mid-high loudspeakers, without unduly harming the stereo separation and
image.
Third, low-frequency waves tend to add together quite graciously, even if their sources are
separated by considerable distances, as long as they are in phase with each other. An example
of this in operation is the typical accentuation or build-up of low-frequency content that is
often experienced in the middle of theatres and concert halls, generated by subwoofers placed
far apart on the opposite sides of the stage.
Overall, the characteristics mentioned above imply that the location of a subwoofer is not
particularly critical, and to a certain extent that is true. However, there are several factors to
consider before you finalize your intended location
(1) A subwoofer will benefit greatly in terms of power output when it's placed adjacent to
boundary surfaces. If located at the junction of three surfaces, such as on the floor or
ceiling in a corner (this is called Eighth Space), a given subwoofer will produce a full 9dB
more output power than if that same subwoofer is located in Free Space (such as when
suspended between the middle of a floor and ceiling). If located at the junction of two
surfaces (Quarter Space), the subwoofer will produce 6dB more output than if suspended
in Free Space. If located on a single wall, such as the floor or ceiling, the increase is 3dB.
Free Power! What could be better? See Figure 8 for additional clarification:
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A thorough understanding of how low-frequency waves transmit in acoustical environments is very helpful when
designing, installing, and optimizing sound systems. We recommend reading such books as "Fundamentals of Sound" and
"Psychoacoustics" by F. Alton Everest in the "Handbook for Sound Engineers" published by Howard Sams & Co.
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. Some of these are:
VERIS 2 – Operation Manual - Page 23