L12-2 Dual Channel Amplifier Board 150W+150W HiFi Stereo Audio Power DC12V-55V

Improvement compared to VER4 version in VER5 version:
1. Replace low-power transistors B649 and D669 with medium power transistors A1837 and C4793,
2. Increase the static current of the driving power transistor from 6MA to 18MA.
3. Add a radiator to the medium power tube.
4. Increase the static current adjustment function of the output power transistor, so that the static current of the left and right channel circuit boards can be the same.
5. Use electronic filters to replace the previous RC passive filters and reduce input stage interference.
6. Change the input stage mode to increase the input impedance.
    Low frequency performance improvement
 

L12-2 is primarily a low-distortion, high-gain, active listening amplifier.

The supply voltage is within +/- 55V.

Parameters:

Power = 120W / 8R +/- 50V Voltage

200W 4R +/- 50V Voltage

THD <0.0005% at 1 kHz with 10W output

SR = 35V/US


The damping coefficient is greater than 200, for an 8 ohm load.

Input sensitivity = 1.6V Output 120W 8Ω

Frequency Range = 15HZ - 50K HZ (-3DB)

20 Hz * 20 k Hz = -0.02 dB

Static Current = 30 mA

Voltage operating range = DC +/- double voltage range + -12V to +/- 55V

Voltage amplification factor = 31 times


The parts need to be soldered together, and after installation, it will look like this:

Static current regulation: Adjust the DC voltage between OUT+, TEST, and 2 points to DC3MV

Test diagram:
Input signal THD+N test
When the input voltage is 700MV, the output voltage is approximately 23VPP and the load is an 8-ohm resistor.
The following test uses an 8 ohm 1000W power resistor

THD+N :

frequency response:

THD+N   VS  FREQUENCY Test chart:

Installation connection diagram
Corresponding power supply with speaker protection amplifier board