Mains Power Supply and 24V DC Emergency Backup Setup
The Ahuja SSA-250DP PA mixer amplifier operates from standard AC mains power at 220–240V AC 50/60Hz, drawing a rated power consumption of 460VA. For continuous industrial plant paging, institutional announcements, and mission-critical public address setups, the amplifier features dedicated rear-panel terminals for 24V DC operation.
Connect an external 24V DC source consisting of two 12V car batteries (they are not included) wired in series to the DC terminal block with strict adherence to polarity. In the event of AC mains power interruption, internal circuitry executes an instantaneous automatic switchover to the 24V DC battery supply (they are not included), drawing up to 6A current under full operational load without causing interruption or signal dropouts.
Speaker Line Routing and Impedance Matching
The amplifier provides multiple speaker terminal output taps designed for either direct low-impedance connections or distributed constant-voltage lines. Ensure the total load connected to the output terminals matches the electrical limits of the 250W RMS (300W maximum) rated power stage.
- Low-Impedance Taps (4Ω and 8Ω): Used for direct connection to standard low-impedance box speakers. Always calculate series/parallel speaker network impedance to match 4Ω or 8Ω exactly. Do not connect low-impedance loads to 70V or 100V terminals.
- Constant Voltage Lines (70V and 100V): Designed for distributed speaker networks spanning long cable distances. Connect only speakers equipped with 100V or 70V line-matching transformers (LMT), such as ceiling speakers and sound columns. Ensure the aggregate wattage sum of all transformer taps does not exceed 250W RMS.
Box Speaker vs. Driver Unit Selector Switch
The rear panel is equipped with a dedicated Box Speaker / Driver Unit selector switch to match output acoustic filtering to the connected transducer type. When driving horn driver units for industrial or outdoor paging, set this switch to 'Driver Unit' mode. This setting automatically defeats the low-frequency bass boost circuit, protecting delicate driver unit voice coils and diaphragms from mechanical damage caused by excessive low-frequency excursion.
When connecting broad-range wooden or molded box speakers, set the switch to 'Box Speaker' mode to retain full tone shaping capability across the 50 Hz to 15,000 Hz (±3dB) frequency response range, including front-panel Bass (±10dB at 100Hz) and Treble (±10dB at 10kHz) adjustments.
Audio Input Interfacing and Amplifier Cascading
Integrate input sources across the 6 microphone input channels (0.65mV/4.7kΩ sensitivity), 2 auxiliary inputs (100mV/470kΩ), or the integrated digital MP3/Bluetooth player. When feeding audio directly from an external master PA audio mixer or another primary mixing console, route the signal into the 1V/50kΩ Line Input.
To expand system wattage capacity, utilize the Line Output (1V/1kΩ) or Preamplifier Output (200mV/600Ω) to daisy-chain additional booster power amplifiers or connect external audio recording units without loading down the primary mixing stage.
Physical Rack and Bench Installation Parameters
| Parameter | Installation Specification |
|---|---|
| Chassis Dimensions | 450 mm (Width) x 160 mm (Height) x 340 mm (Depth) |
| Net Unit Weight | 16.0 kg |
| Primary AC Input | 220–240V AC, 50/60 Hz (460VA) |
| Secondary DC Input | 24V DC (2 x 12V external batteries (they are not included), 6A) |
| Output Tap Terminations | 4Ω, 8Ω, 70V, 100V |
| Overcurrent Protection | Rear-panel resettable thermal-magnetic circuit breaker |
