SP 4.500 features Hertz ADC (Advanced D-Class) output stage, reaching up to 85% efficiency and delivering an impressive power rating of 90 x 4 (4Ω) W RMS or 300 W x 2 (4Ω) W RMS when bridged, with an ultra-compact size of 192.7 (7.58) x 130 (5.1) mm (in.) x 49 (1.9). Being ultra-compact with impressive power, SP 4.500 is the ideal choice for Motorcycle applications and for under-seat in sports cars and behind-seat installations in trucks. General Specs Channels: 4 - 3 - 2 Nominal power supply voltage: 11 ÷ 15 VDC Pulse Operating voltage: 6 ÷ 16 VDC Idling current: 0.9 A Idling current when off: 0.03 mA Consumption @ 14.4 VDC, MIN load impedance (Max Musical Power): 27 A Remote IN: 6 ÷ 15 VDC (9 mA) DC-REM - Remote Turn on by SPK DC from OUTPUT BTL speakers: 3.5 ÷ 7 VDC Distortion - THD @ 1 kHz, 4Ω, 70% Rated Power: 150 Bandwidth @ -3 dB: 10 Hz ÷ 35 kHz S/N ratio (A weighted @ 1 V Input): 100 dBA Pre-In sensitivity: 0.6 ÷ 6 VRMS Speaker-In sensitivity: 2.2 ÷ 22 VRMS Minimum load impedance: @ 4Ch: 2Ω @ 3Ch: 2Ω + 2Ω + 4Ω @ 2Ch: 4Ω IP Rating: IP55 Operating Temperature Range: 0°C (32°F) to 55°C (131°F) Max size (mm/inch): 192.7 x 130 x 49 / 7.58 x 4.18 x 1.9 Weight (kg/lbs): 2.15 / 4.74 Adjustable Crossovers: yes