5. Voice Alarm Systems Adjusting the Audio Gain Level (AA-30, AA-100/AA-120)
38 Unimode 400 Operations PN 50709:A 10/20/97
Adjusting the Audio Gain Level (AA-30, AA-100/AA-120)
An audio amplifier contains a multi-position rotary switch that lets you adjust the gain
of the audio output signal. This adjustment compensates for audio line losses. After
correct adjustment, an audio amplifier can produce its maximum rated output power of
25 Vrms (AA-30, AA-120) or 70.7Vrms (AA-100). Refer to Figure 37 on page 37 for
the location of the Audio Gain Rotary Switch.
When finished installing all amplifiers and associated circuitry, adjust the audio gain as
follows:
1. Locate the Audio Gain Rotary Switch on the AA-30 (Figure 36) or the AA-100/
AA-120 (Figure 37).
2. Use a small slotted screwdriver to turn the Audio Gain Rotary Switch until the
Normal Level LED and Incorrect Level LED are properly adjusted as shown in
Table 34:
Table 34 Adjusting the AA-30/AA-100/AA-120 Audio Level
Selecting the AA-100/AA-120 Backup Tone
An audio amplifier automatically produces a backup tone when the low-level audio
input is lost. You can select the backup tone by following these steps.
1. Locate SW1 in the lower right-hand corner of the AA-100/AA-120 circuit board
(See Figure 37 on page 37).
2. Set SW1 to Hi/Lo or Slow Whoop as the default backup tone (Figure 38).
Figure 38 LSW1 Backup Tone Switch (AA-100/AA-120 only)
Audio Level Normal Level LED Incorrect Level LED
Properly adjusted ★✩
Adjusted too low ✩★
Adjusted too high ★ ★
★ LED on ✩ LED off
Hi/Lo Slow Whoop
Caution: Remove AC
power at the main service
circuit breaker (not the
circuit breaker on the main
power supply).
!
Audio Gain Rotary Switch
(See Figure 37 on page 37
for location of switch.)