Audio Amplifier 35 W, 25 V / 70 V / 100 V with Power Supply

The RDL FP-PA35A is a 35 W RMS mono amplifier designed to power multiple 25 V, 70 V, or 100 V speakers from a single line-level input. It accepts nominal +4 dBu balanced or -10 dBV unbalanced audio and includes a universal power supply. Selectable sleep operation, automatic compression, status indicators, and protective features support dependable integration into distributed audio systems.

Ideal Use Cases

This model is suited to systems that require one mono amplifier channel to serve multiple constant-voltage speakers. Its support for 25 V, 70 V, and 100 V speaker systems allows the same amplifier model to address different system voltage requirements while delivering 35 W RMS of rated output power.

The line-level input accommodates both balanced and unbalanced sources. Nominal input levels are +4 dBu balanced and -10 dBV unbalanced, with maximum levels of +22 dBu and +20 dBV respectively. A UL 2043 plenum rating also makes the FP-PA35A appropriate for installations where that rating is specified.

Why Choose This Model

The FP-PA35A combines three constant-voltage output options with automatic energy-saving operation. Its selectable sleep delay can be set to 5, 15, or 25 minutes, or sleep mode can be disabled. When sleep mode is active, combined consumption for the amplifier and included power supply is less than 1 W.

Audio detection returns the amplifier to active mode in less than 150 milliseconds after input audio is detected. This allows the amplifier to remain energy conscious between periods of use while responding quickly when a source becomes active.

Installation and Integration

Detachable terminal blocks are used for the audio input and output connections, helping simplify wiring and servicing. Input impedance is 20 kΩ balanced bridging or 10 kΩ unbalanced. A single-turn audio-taper gain adjustment provides local control of the amplifier level.

The included ground-referenced power supply accepts 100 to 240 Vac at 50-60 Hz through an IEC C14 connection and provides 24 Vdc at 2 A to the module. The amplifier measures 2.80 inches high, 3.25 inches wide, and 6.04 inches long, equivalent to 7.1 by 8.26 by 15.3 centimeters. Its specified operating environment is 0°C to 40°C maximum, with 20°C recommended.

Performance Highlights

Rated output is 35 W RMS at 25 V, 70 V, or 100 V. Frequency response extends from 50 Hz to 20 kHz within ±3 dB. THD+N is specified below 0.5% at 1 kHz at the compressor threshold and below 0.5% from 50 Hz to 20 kHz at 1 W. CMRR is greater than 60 dB from 50 Hz to 120 Hz.

The integrated compressor has a threshold 2 dB below rated output and automatically adjusts its attack and release times. A red PEAK LED indicates compressor activity. The blue power LED is dim while sleep mode is active and bright while the amplifier is active, providing an immediate view of operating status.

What Makes It Different

The ability to power 25 V, 70 V, or 100 V speakers distinguishes this amplifier as a flexible choice for constant-voltage audio systems. Its combination of selectable sleep timing, less-than-1-watt sleep consumption, rapid return to active operation, and automatic compression addresses both operating efficiency and signal management.

The FP-PA35A is plenum rated according to UL 2043 and includes additional short-circuit and thermal protection. These specifications complement its detachable connections and included power supply, giving system designers a clearly defined set of installation and operating characteristics.

Final Assessment

For a mono distributed-speaker system requiring up to 35 W RMS, the RDL FP-PA35A provides broad 25 V, 70 V, and 100 V output compatibility in a compact module. Balanced and unbalanced line-level support, selectable sleep behavior, automatic compression, visible operating indicators, UL 2043 rating, and the included universal power supply make it a well-specified amplifier for installations that match its power and frequency-response requirements.