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Speaker Layout

To determine the layout of the speakers to be installed indoors and the electric power (W) to be applied to the speakers, the purpose of the speakers and their directivity pattern and output sound pressure, and acoustic characteristics of the room (reverberation, noise level, sound insulation, etc.) should be reviewed.
To determine the layout of the speakers to be installed outdoors, the climate condition and presence of obstacles should be additionally checked.


Speakers can be arranged or located in the following three formations: 1) Concentration, 2) Distribution and 3) Concentration and distribution.
Before determining the layout of your speaker system, review the advantages and disadvantages of these arrangements.

Title1

Sound sources (speakers) are collectively installed at a position or placed to radiate the sound in the same direction.

a) Advantages

  • Gives a better directional sensitivity to listeners.
    During a lecture, speech, concert, etc., the sounds should be heard as if they directly come from their origin.
  • No or small time difference
    Because there is no sound source around (front, back, left, right, above and below) the single sound source, sounds reach the ears at the same time or almost the same time.
  • Wiring work cost is low.

b) Disadvantages

  • Difficult to obtain uniform sound pressure level.
    The sound pressure level is high near the speaker and low at a remote location. (With a line array speaker, decay of sound is minimum.)
  • Sound intelligibility is low in a room with longer reverberating time.
  • Higher output power is required when noise level is high.
    The sound pressure level at the speaker should be higher than the noise level by 6 to 10 dB for masking. To increase the sound level by 6 dB, input power to the speaker should be increased 4 times. For example, when the sound pressure level at a distance from a speaker driven by 20 W is 75 dB and the noise level at this position is also 75 dB, the sound pressure level from the speaker should be at least 81 dB, which requires 80 W or higher input.

Figure1_a
Figure1_b


Title2

Sound sources (speakers) are dispersively located.

a) Advantages

Uniform sound pressure level is obtained.

  • High sound intelligibility is maintained even in a room with longer reverberating time.
    Each speaker is driven by low power and radiates sound within a small area, applying low sound pressure to sound reflecting material to minimize the reflected sound volume.
  • Lower output power can overcome high level noise.
    Many speakers are decentralized-arranged; each delivers small volume sound within the predetermined limited space.
  • Not loud even in a low-ceilinged room
    By dispersively installing many speakers on the ceiling, uniform sound pressure level can be obtained.

b) Disadvantages

  • Difficult to give correct directional sensing.
  • Intelligibility becomes poor at excessively high output.
    Sounds from many speakers interfere with each other, degrading quality of mixed sound.
  • Cost of wiring work is higher than that of concentrated system.

Figure2_a
Figure2_b


Figure3_title
Ceiling HightDistance between speakersArea coverage of a speaker
2.5m max.5mApprox.25m2
2.5m - 4.5m6mApprox.36m2
4.5m - 15m9mApprox.81m2


Title3

This system can be operated in two ways: activate both concentrated and distributed speakers at the same time, and selectively activate either one depending on the purpose.
In the former arrangement, the concentrated speakers are used to provide the desired sound pressure level while the small output speaker(s) is used as supplementary at localized space where sound level is low. In this arrangement, a delay unit will be required for the supplementary speaker to offset time difference between its sound and the sound from the concentrated speakers.


For refer to TOA speakers, click here