AB400 dual channel professional stage amplifier board circuit design is mature and stable, the use of double differential input and increase the input signal processing, the push stage with a pair of 1930/5171 and 5200/1943 to do compound push, and then 16 tubes to do the power output stage, the output power up to 400W+400W. Great power, strong low frequency, rich details, the circuit adopts DC feedback design, good analytical power, good bass deep elasticity, stable work under high power, retracting and retracting freely. The board design has a perfect protection circuit, including switch delay protection, to prevent impact sound. Midpoint voltage protection, overcurrent protection, high temperature protection, and cooling fan interface. Selected TTA1943/TTC5200 audio tube, carefully matched after assembly. Model:AB400 Output channel: 2.0 channel Magnification: 25x Power amplifier tube: TTA1943 x 8, TTC5200 x 8 Frequency response range:20-20KHz Main voltage: DC dual 50V-110V, you need to add a rectifier board yourself Output power: 400W+400W/4Ω, 200W+200W/8Ω Total harmonic distortion: 0.01% Protection mechanism: overheating protection, overcurrent protection, midpoint voltage protection, power-on delay protection Size: 220 x 84 x 100mm Material: plastic+metal Color as shown Package Contents: 2 x Amplifier board