Description: Rated supply voltage is 65V, 58---70V range, do not over 70V! positive and negative do not pick wrong. Recommended power supply 65V. Recommended 4-8 / 10-18inch speaker Carefully check before electricity, ensure the wiring is correct. Output short circuit protection: Yes That output DC bias protection speaker protection: Yes Over-temperature protection: Yes, radiator FET temperature higher than 100 C, turn off the output! Specification: Power Supply: dual DC power supply 58 --- 70V Rated Output Power: 500W ( 65V power supply, 4 ohm load, distortion 10%) Efficiency:> = 90% SNR: 90dB The total harmonic distortion: -380W ( 65 power 4 ohm speaker, distortion<0.1%) -280W ( 65 power 8 ohm speaker, distortion<0.1%) Frequency range: 20Hz-20KHz Speaker: 4-8 Voltage Magnification: 36 times Input sensitivity 1.5V (RMS) Material: Plastic Size: Approx. 100x50x30mm / 3.94x1.97x1.18 inch Package Includes: 2 Pieces Digital Amplifier Module Note: Please allow a slight difference between the size from the above and the actual item due to manual measurement.