Max Spl Table - JBL Control 24C Application Manual

downward adjustment of at least 4 dB must be made to the maximum pink noise computation to reflect the
maximum average SPL capability for music or speech.
To compute the "Maximum SPL (Sound Pressure Level) of Music or Speech" of a single loudspeaker use
the following formula:
MAX AVERAGE SPL (for MUSIC AND SPEECH) =
10 (log (PINK NOISE POWER HANDLING)) + SENSITIVITY – 4 – 20(log(DISTANCE IN METERS))
The answer is in decibels (dB)
For those who want to know more about this formula, this is how it is derived:
a) MAXIMUM AVERAGE SPL (at 1 meter distance) is computed by taking 10 times the log of the PINK NOISE
POWER HANDLING (the "power capability" specification) and then adding the SENSITIVITY specification.
b) By definition, the computation for MAXIMUM PEAK SPL (at 1 meter distance) for pink noise is the MAXIMUM
AVERAGE SPL (at 1 meter distance) plus 6 dB.
c) We have found that typical music and speech signals used for business music have a peak-to average ratio around 10 dB.
Therefore, the MAXIMUM AVERAGE MUSIC AND SPEECH SPL (at 1 meter distance) is 10 dB lower than the
MAXIMUM PEAK SPL (at 1 meter distance).
d) To determine the MAXIMUM AVERAGE MUSIC AND SPEECH SPL at a certain distance from the speaker, take the
log of the DISTANCE from the speaker (in meters) and multiply that by 20. Subtract the resulting figure from the
MAXIMUM AVERAGE MUSIC AND SPEECH SPL figure for 1 meter.
e) Therefore, the final equation is: MAXIMUM AVERAGE SPL FOR MUSIC AND SPEECH is 10 times the log of the
POWER HANDLING spec plus the SENSITIVITY spec minus 4 dB minus 20 times the log of the DISTANCE from
the speaker (in meters).
Max SPL Table -- The following table shows the maximum continuous and peak SPL capabilities of
the Control Contractor models on-axis with the loudspeaker at a 4 ft (1.2 m) listening plane for a
SINGLE loudspeaker with NO overlapping coverage from adjacent loudspeakers:
The SPL capability in MULTIPLE speaker systems is HIGHER than what is indicated in this table by
as much as +6 dB, depending on layout pattern and density. See Table 7 in the Speaker Layout and
Spacing section below for the additional SPL capability from MULTIPLE speaker systems.
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10 Ft (3.1 m) Ceiling
Avg Music & Speech
Avg Pink Noise
Peak
14 Ft (4.3 m) Ceiling
Avg Music & Speech
Avg Pink Noise
Peak
Note: This chart assumes adequate amplification and does not take power compression into consideration.
1
Control 24CT at 30 W tap, takes the transformer insertion loss into consideration.
2
Control 26CT at 60 W tap, takes the transformer insertion loss into consideration.
3
Control 19CS & 19CST figures are for installation within 3 feet of a corner. For speaker installation near one wall,
reduce the figures by 3 dB. For speaker installation in the center of the ceiling, reduce the figures by 6 dB.
6
7DEOH 
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(On-Axis)
Control
1
24C 24CT
92 dB 90 dB
96 dB 94 dB
102 dB 100 dB
88 dB 86 dB
92 dB 90 dB
98 dB 96 dB
Control
2
26C 26CT 19CS
98 dB 96 dB 103 dB
102 dB 100 dB 107 dB
108 dB 106 dB 113 dB
94 dB 92 dB
98 dB 96 dB 103 dB
104 dB 102 dB 109 dB
Control
3 3
19CST
101 dB
105 dB
111 dB
99 dB 97 dB
101 dB
107 dB