Digital Amplifier Board Professional 500W HiFi Single Channel Class D Sound Amplifier Module for DIY Sound System Item Type: Digital Power Amplifier Board Material: PCB Power Amplifier Plate Size: Approx. 105x43x28mm / 4.13x1.69x1.10in Supply Voltage: Dual DC Power Supply ± 45 - ± 70V (Recommended +-65V Power Supply Can Be) Rated Output Power: 500W (±65V Power Supply 4 Ohm Load, Distortion 1%) Efficiency: >= 90% SNR: 90db Total Harmonic Distortion: 380W (±70 Powered 4 Ohm Speaker, Distortion <0.1%) 280W (±70 Powered 8 Ohm Speaker, Distortion <0.1%) Frequency Response Range: 20Hz-20KHz Horn: 4-8Ω Voltage Amplification: 50 Times Input Sensitivity 1V (RMS) Output DC Bias Protection I.E. Horn Protection: Yes