HA5K FET Pure Class A Headphone Amplifier DIY Kit/Finished Board Base On Audio Tec-hnica HA5000 Amp Circuit

This is a Full Separate Pure Class A headphone amp. the circuit is base on the famous HA5000. the sound is very Excellent!! Using Toshiba 2SK370 FET as a single differential input, sound is very delicate, K2955 J554 power FET as the output, low frequency is very full, very flexible. On the amp Board with a gain switch, you can set the magnification depending on headset. Works voltage: AC 15V--0--15V Load impedance 16-600 Ohm Sensitivity of 1.1 V / 50,000 ohms Maximum output power 2,400 mW + 2,400 mW (16 ohm load) 1,200 mW + 1,200 mW (32 ohm load) 600 mW + 600 mW (64 ohm load) 65 mW + 65 mW (600 ohm load) Input impedance: 47KOhm Frequency characteristics: 10Hz - 35kHz Signal ratio for noise: >90dB @ Gain 6dB Output impedance: line output 0.2 Ohms Frequency Response 5 ~ 200,000 Hz PCB Size: 130mm*112mm Debugging method: 1. Measure the TEST1A and TEST2A points, adjust the 2K blue adjustable resistor to adjust the voltage between DC 20mV and 80V. Please make sure to determine according to the temperature of your heat sink. 2. Measure the TEST1B and TEST2B points, adjust the 100R blue adjustable resistor to make the voltage close to DC 0mV. NOTE: We have DIY kit or Finished board (Optional) ◆ DIY kit ---- All parts need you to solder and test it. (Without a potentiometer) ◆ Finished board ---- All parts have been welded and tested OK.