JBL Control 24C Application Manual

Also see for Control 19CS: Owner's manual Owner's manual

Contents

6downward adjustment of at least 4 dB must be made to the maximum pink noise computation to reflect themaximum average SPL capability for music or speech.To compute the “Maximum SPL (Sound Pressure Level) of Music or Speech” of a single loudspeaker usethe 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 NOISEPOWER 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 MAXIMUMAVERAGE 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 theMAXIMUM PEAK SPL (at 1 meter distance).d) To determine the MAXIMUM AVERAGE MUSIC AND SPEECH SPL at a certain distance from the speaker, take thelog of the DISTANCE from the speaker (in meters) and multiply that by 20. Subtract the resulting figure from theMAXIMUM 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 thePOWER HANDLING spec plus the SENSITIVITY spec minus 4 dB minus 20 times the log of the DISTANCE fromthe speaker (in meters).Max SPL Table -- The following table shows the maximum continuous and peak SPL capabilities ofthe Control Contractor models on-axis with the loudspeaker at a 4 ft (1.2 m) listening plane for aSINGLE loudspeaker with NO overlapping coverage from adjacent loudspeakers:The SPL capability in MULTIPLE speaker systems is HIGHER than what is indicated in this table byas much as +6 dB, depending on layout pattern and density. See Table 7 in the Speaker Layout andSpacing section below for the additional SPL capability from MULTIPLE speaker systems.7DEOH&21752/&2175$&7256,1*/(63($.(563/&$3$%,/,7<(On-Axis)Control Control Control24C 24CT 1 26C 26CT 2 19CS 3 19CST 310 Ft (3.1 m) CeilingAvg Music & SpeechAvg Pink NoisePeak92 dB96 dB102 dB90 dB94 dB100 dB98 dB102 dB108 dB96 dB100 dB106 dB103 dB107 dB113 dB101 dB105 dB111 dB14 Ft (4.3 m) CeilingAvg Music & SpeechAvg Pink NoisePeak88 dB92 dB98 dB86 dB90 dB96 dB94 dB98 dB104 dB92 dB96 dB102 dB99 dB103 dB109 dB97 dB101 dB107 dBNote: 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.