JBL LSR28P, Technical & Service Manual

Page: 15 / 75

15
INPUT SENSITIVITY
The LSR28P is very versatile in that the input audio sensitivity can be adjusted. Monitor inputs
are normally at nominal levels of +4 dBu or –10dbv. These input levels are called professional and
semiprofessional, respectively, and reflect the type of connectors used for hookup. The nominal level for
the XLR input is +4 dBu and -10 dBv for the 1/4" TRS input. If less sensitivity is needed to match other
brands of professional or semiprofessional equipment, 4,8, or 12 dB of signal attenuation can be inserted
in the input line by using the DIP switches on the back of the LSR28P. See the illustration below:
Located on the right of the Neutrik connector but before the power switch, is a bank of switches that are
accessible with the use of a pen or a very small screwdriver. These are the DIPswitches.
•
Switch 1-enables the input trim potentiometer when switched to the up position. This
potentiometer is located to the left of the bank of DIPswitches and can be accessed
with a small screwdriver. This allows the user to attenuate the input level from the
fixed; factory set default of +4 dBu to a variable input level from +4 dBu to –12 dBu.
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Switch 2—attenuates the input level by a fixed 4 dBu
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Switch 3—attenuates the input level by a fixed 8 dBu.
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Switch 4—aligns the bass response to roll off at 24 dB per
Octave
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Switch 5—aligns the bass response to roll off at 36 dB per
Octave corresponding to a –2 dB bass response
•
Switch 6—keeps the bass response at 36 dB per Octave but
Increases the emphasis of bass frequ2 dB
•
Switch 7—attenuates only the High Frequency amplifier
Input level by -2 dB.
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Switch 8—enhances the High Frequency amplifier input
Level by +2 dB