1. Power supply: dual DC power supply 58 --- 70V 2. The rated output power: 500W ( 65V power supply, 4 ohm load, distortion 10%) 3. Efficiency:more than the = 90% 4. : 90dB 5. The total harmonic distortion:380W ( 65 power 4 ohm speaker, distortion Less than 0.1%) 280W ( 65 power 8 ohm speaker, distortion Less than 0.1%) 6. Frequency range: 20Hz-20KHz 7. Speaker: 4-8 ohm 8. Voltage Magnification: 36 times 9. Input sensitivity 1.5V (RMS) 10. Output short circuit protection: Yes 11. That output DC bias protection speaker protection: Yes 12. Over-temperature protection: Yes, radiator FET temperature higher than 100 Celsius, turn off the output! Colour: Material:ABS Size:98 x 43 x 30mm Package Contents: 1 * Digital power amplifier board Use precautions: 1. Rated supply voltage is 65V, 58---70V range, do not over 70V! positive and negative do not pick wrong 2. Recommended power supply 65V 3. Recommended 4-8 / 10-18inch speaker 4. Carefully check before electricity, the wiring is correct.