TOA bs-1030 User Guide
TOA Electronics Speaker Guide
Layout and Spacing for Distributed Speaker Systems
29
Speaker Spacing and Layout Pattern
Because of the triangular shape of the coverage area, wall-mount speakers work best when
placed on facing walls and staggered so that each speaker is aimed at a point mid-way between
two speakers on the opposite wall, at about ear level. The best spacing between speakers depends
on their height and distance to the opposite wall. This is because the width of the triangular
coverage area is proportional to its depth. Recommended spacings for all of TOA’s wall-mount
speaker models are listed in Chapter 8: Speaker Application Tables.
placed on facing walls and staggered so that each speaker is aimed at a point mid-way between
two speakers on the opposite wall, at about ear level. The best spacing between speakers depends
on their height and distance to the opposite wall. This is because the width of the triangular
coverage area is proportional to its depth. Recommended spacings for all of TOA’s wall-mount
speaker models are listed in Chapter 8: Speaker Application Tables.
Subwoofers
To calculate the number of subwoofers needed, determine the maximum rated output of a
single subwoofer (see The Decibel on page 17, and Determining Maximum Output: Sensitivity
and Power Handling on page 21), and add a placement factor to this value (see below). Then add
subwoofers until this level is 6–9 dB higher than the main speakers. To increase the distributed
subwoofer level by 3 dB, double the number of subwoofers and the total power driving them.
single subwoofer (see The Decibel on page 17, and Determining Maximum Output: Sensitivity
and Power Handling on page 21), and add a placement factor to this value (see below). Then add
subwoofers until this level is 6–9 dB higher than the main speakers. To increase the distributed
subwoofer level by 3 dB, double the number of subwoofers and the total power driving them.
Placement Factor: The placement of the subwoofers with respect to walls, floors, and other
hard boundaries affects the system amplitude response. Compared to a subwoofer suspended
in free air, a subwoofer next to one rigid wall increases its output 3–6 dB with the same power
input, depending how close it is to the wall (the closer the better). A subwoofer located in a
junction between two boundaries (two walls, one wall and floor or ceiling) increases its output
6–9 dB. A subwoofer located in the junction between three boundaries (two walls and the floor
or ceiling) increases its output 9–15 dB (equivalent to increasing the input power by a factor of
8–30). Note the conditions under which the subwoofer was rated (i.e., half-space, which means
against, or built into, one boundary), and when calculating maximum output, factor in the
speaker placement in comparison to the measurement condition. For example, if the speaker
was measured under half-space conditions, but will be used on the floor in a corner, then add
6–9 dB to the speaker’s maximum output level.
hard boundaries affects the system amplitude response. Compared to a subwoofer suspended
in free air, a subwoofer next to one rigid wall increases its output 3–6 dB with the same power
input, depending how close it is to the wall (the closer the better). A subwoofer located in a
junction between two boundaries (two walls, one wall and floor or ceiling) increases its output
6–9 dB. A subwoofer located in the junction between three boundaries (two walls and the floor
or ceiling) increases its output 9–15 dB (equivalent to increasing the input power by a factor of
8–30). Note the conditions under which the subwoofer was rated (i.e., half-space, which means
against, or built into, one boundary), and when calculating maximum output, factor in the
speaker placement in comparison to the measurement condition. For example, if the speaker
was measured under half-space conditions, but will be used on the floor in a corner, then add
6–9 dB to the speaker’s maximum output level.
Fraction-space loading can be described in greater detail as follows:
The maximum SPL of a subwoofer is increased by placing it against one or more boundaries. This
effect, known as bass or fraction-space loading, begins to occur when the speaker is within 1/8
wavelength at a given frequency from the boundary, and increases the output 3–6 dB (de-
pending on the actual distance) for each boundary. For example, at 100 Hz (wavelength = 11.3 ft),
with the subwoofer positioned 2.825 ft from the floor, the level will be 3 dB higher than a subwoofer
suspended in free air. A subwoofer flush-mounted onto the floor or a large wall (known as half-
space loading) has a level 6 dB higher than if it were suspended in free air. Each additional boundary
increases the output 3–6 dB. For example, placing the subwoofer at the junction of two bound-
aries (quarter-space loading) adds 6–12 dB; three boundaries (eighth-space loading) increases
the output 9–15 dB. These boundaries must be massive and rigid enough to contain the wave front
without flexing. Thin materials, such as curtains or temporary walls, will not produce this effect. The
surfaces must be large enough to support the wavelength of the relevant frequencies; at least one
wavelength of surface dimension is required to gain the full 6 dB increase.
effect, known as bass or fraction-space loading, begins to occur when the speaker is within 1/8
wavelength at a given frequency from the boundary, and increases the output 3–6 dB (de-
pending on the actual distance) for each boundary. For example, at 100 Hz (wavelength = 11.3 ft),
with the subwoofer positioned 2.825 ft from the floor, the level will be 3 dB higher than a subwoofer
suspended in free air. A subwoofer flush-mounted onto the floor or a large wall (known as half-
space loading) has a level 6 dB higher than if it were suspended in free air. Each additional boundary
increases the output 3–6 dB. For example, placing the subwoofer at the junction of two bound-
aries (quarter-space loading) adds 6–12 dB; three boundaries (eighth-space loading) increases
the output 9–15 dB. These boundaries must be massive and rigid enough to contain the wave front
without flexing. Thin materials, such as curtains or temporary walls, will not produce this effect. The
surfaces must be large enough to support the wavelength of the relevant frequencies; at least one
wavelength of surface dimension is required to gain the full 6 dB increase.