The FP-PA20B is part of the group of versatile FLAT-PAK products from Radio Design Labs The unique FLAT-PAK case can be directly screwed or bolted to cabinets or shelves Optionally available rack-mounting accessories permit single or multiple FLAT-PAK module mounting APPLICATION: The FP-PA20B is the ideal choice in many applications where multiple 25 V speakers in a zone need to be powered from a single audio power amplifier The FP-PA20B features a balanced line level input that may be connected unbalanced Input: Line level (+4 dBu bal; -10 dBV unbal)Input Impedance: 20 kΩ balanced bridging; 10 kΩ unbalInput / Output Connector: Plug-in terminal blockGain Adjustment: Single turn audio taperMinimum Input Levels:Balanced: -26 dBu (to cross compressor threshold)Unbalanced:-28 dBV (to cross compressor threshold)Maximum Input Levels:Balanced:+23 dBuUnbalanced: +15 dBVFrequency Response:50 Hz to 18 kHz (+/- 3 dB)*THD+N: *measured at compressor threshold level equaling 4 W RMS output power. < 0.1% (@ 1 kHz)* < 0.5% (50 Hz to 20 kHz)*Noise:< -80 dB (below 20 W RMS)Compressor:Threshold 6 dB below rated output, automatic adjusting attack and releaseCMRR: 55 dB (50 Hz to 120 Hz)Output Power:20 W RMS @ 25 VAmbient Operating Environment:0?? C to 30?? C Max; 20?? C RecommendedIndicators (2):Red LED:PEAK LED indicates compressor activityGreen LED:Power ONPower Requirement:24 Vdc @ 2000 mA, Ground referenced(for continuous RMS power output) 24 to 33 Vdc @ 1000 mA, Ground referenced (for normal uncompressed audio)