TOA bs-1030 Mode D'Emploi
TOA Electronics Speaker Guide
Using Speaker Specifications
23
Coverage Angle
The coverage angle of a speaker is the angle within which the SPL is no more than 6 dB below
the normalized on-axis level for a given bandwidth or frequency center. The desired coverage
angle for a speaker depends on its role in the system, the number and spacing of speakers, and
the acoustical environment. Typically, distributed speaker systems and background music systems
need medium to wide dispersion speakers (coverage angle
the normalized on-axis level for a given bandwidth or frequency center. The desired coverage
angle for a speaker depends on its role in the system, the number and spacing of speakers, and
the acoustical environment. Typically, distributed speaker systems and background music systems
need medium to wide dispersion speakers (coverage angle
≥
60°). If the speakers are close to
the listeners, for example in a low-ceiling room or pew-back speakers in a church, then wide
dispersion is especially desirable (coverage angle
dispersion is especially desirable (coverage angle
≥
100°). Nominal coverage angle ratings of
TOA speaker models are listed in Chapter 8: Speaker Application Tables. Polar plots depicting
the coverage angle at standard frequency bands are found on our speaker specification sheets,
which may be downloaded at
the coverage angle at standard frequency bands are found on our speaker specification sheets,
which may be downloaded at
Frequency Response
Frequency response refers to the frequency range over which the speaker responds, usually with
a tolerance range for level variation. For example, a frequency response rating of 35 Hz – 18 kHz
±3 dB is typical of a professional studio monitor. The rating means that with constant input at
all frequencies, the output over the stated frequency range will fall within a 6 dB window (3 dB
above and below 0 dB) of variation. In general, a wider frequency response range indicates
higher fidelity sound reproduction. However, restricting the frequency range (i.e., switching on
the low-cut filter) can be an advantage in installed sound systems in order to:
a tolerance range for level variation. For example, a frequency response rating of 35 Hz – 18 kHz
±3 dB is typical of a professional studio monitor. The rating means that with constant input at
all frequencies, the output over the stated frequency range will fall within a 6 dB window (3 dB
above and below 0 dB) of variation. In general, a wider frequency response range indicates
higher fidelity sound reproduction. However, restricting the frequency range (i.e., switching on
the low-cut filter) can be an advantage in installed sound systems in order to:
•
Avoid upward masking of consonants by low frequency energy, especially in reverberant
spaces.
spaces.
•
Increase system headroom and avoid distortion at high levels.
•
Maximize the overall system performance/cost ratio.
The following approximate frequency response guidelines are for specific applications and
environments:
environments:
•
Speech-only paging system (with or without emergency signaling) for a noisy environ-
ment: 350 Hz – 5 kHz
ment: 350 Hz – 5 kHz
•
Speech-only indoor environment: 120 Hz – 10 kHz
•
Low-level background music: 100 Hz – 10 kHz
•
Foreground music, high-quality background music and audio-visual applications: 80 Hz
or lower – 16 kHz or higher. Achieving the desired low-frequency response may require
a subwoofer in addition to high-quality main speakers.
or lower – 16 kHz or higher. Achieving the desired low-frequency response may require
a subwoofer in addition to high-quality main speakers.