External attenuator connection (4-wire system) – Toa VM-3000 Series User Manual
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VM-3240VA/3360VA/3240E/3360E
(+)
Relay Control
(–)
N
C
SP
Speaker
Attenuator
14.8.3. External attenuator connection (4-wire system)
Two types of attenuators are connectable to this unit, one to be bypassed when 24 V DC is applied to the attenuator,
and the other to be bypassed when the 24 V DC being normally applied to is cut off (in no voltage mode).
Connections of the unit's attenuator control output and 24 V DC output terminals differ depending on the
attenuator types as shown below.
[Example 1]
Operation status of the VM amplifier and the corresponding attenuator operation
VM-3240VA/3360VA/3240E/3360E
(+)
Relay Control
(–)
N
C
SP
Speaker
Attenuator
Note
The system in Example 2 is more fail-
safe than that in Example 1.
Operation status of VM amplifier
Applied voltage to the attenuator
Attenuator operation
Normal mode
No-voltage
Normal operation
At the time of emergency broadcast, or
24 V DC
Bypassed
Priority 1 or 2 broadcast
Operation status of VM amplifier
Applied voltage to the attenuator
Attenuator operation
Normal mode
24 V DC
Normal operation
At the time of emergency broadcast, or
No-voltage
Bypassed
Priority 1 or 2 broadcast
[Example 2]
Operation status of the VM amplifier and the corresponding attenuator operation