The System Sensor V4R2475ADA Speaker Strobe 75 Candela is a legacy audible/visible fire alarm notification appliance from the System Sensor V400 Series. It combines an emergency voice speaker with a fixed 75-candela strobe for fire alarm voice evacuation applications.
The V4R2475ADA supports both 25V and 70.7V speaker circuits and provides selectable speaker power taps from ¼ to 2 watts. The speaker and strobe use separate circuits, allowing independent connection to compatible audio and notification appliance circuits.
Product Functions
- Provides emergency voice notification
- Provides visible fire alarm notification
- Combines speaker and strobe functions
- Fixed 75-candela visual output
- Supports 25V audio systems
- Supports 70.7V audio systems
- Provides selectable speaker wattage
- Supports evacuation messages
- Supports emergency announcements
- Supports live paging
- Supports prerecorded messages and tones
- Separate speaker and strobe circuits
- Designed for compatible voice evacuation systems
Emergency Voice Speaker
The V4R2475ADA incorporates a speaker designed for clear reproduction of emergency voice messages and signaling tones.
Typical functions include:
- Evacuation instructions
- Emergency announcements
- Prerecorded messages
- Alert tones
- Live emergency paging
The published speaker frequency range is:
400–4,000 Hz
25V / 70.7V Audio Operation
The speaker supports:
25 VRMS
70.7 VRMS
This dual-voltage capability allows the appliance to operate with common distributed fire alarm voice evacuation systems.
Selectable Speaker Wattage
The V4R2475ADA provides four selectable speaker power taps:
¼ W
½ W
1 W
2 W
The appropriate wattage can be selected according to required sound level, ambient noise, amplifier capacity, and emergency voice coverage.
75 Candela Strobe
The V4R2475ADA incorporates a fixed:
75 cd strobe
The visual portion operates from a compatible 24V notification appliance circuit and provides visible fire alarm notification.
Unlike multi-candela appliances, the V4R2475ADA has a fixed 75-candela visual output.
Separate Speaker & Strobe Circuits
The speaker and strobe portions operate from separate circuits.
The speaker connects to the compatible emergency voice/audio circuit, while the strobe connects to the appropriate notification appliance circuit.
This allows the system to manage audible voice and visible notification according to the fire alarm system design.
Electrical & Audio Information
Model: V4R2475ADA
Series: V400
Device Type: Speaker Strobe
Strobe Output: 75 cd
Strobe Voltage: 24 VDC
Speaker Voltage: 25 / 70.7 VRMS
Speaker Taps: ¼ / ½ / 1 / 2 W
Speaker Frequency: 400–4,000 Hz
Maximum Speaker Output: Approximately 90 dBA at 2 W
Notification Type: Audible / Visible
Product Status
The V4R2475ADA is a discontinued legacy System Sensor V400 Series notification appliance.
For replacement applications, the existing speaker voltage, wattage, strobe intensity, notification circuit voltage, and voice evacuation system compatibility should be verified.



