AB400 Dual-Channel Amplifier Board 400W×2 TA1943/TTC5200 2.0 High Hifi Power for Passive Speaker

The AB400 is a dual-channel professional stage amplifier board built around TA1943/TTC5200 tubes that are carefully matched after assembly. The design includes a comprehensive protection suite — midpoint voltage protection, overcurrent protection, high-temperature protection and a cooling fan interface — plus switch-delay protection to prevent impact sound at power-up. Signal and power architecture: the circuit uses a stable double-differential input stage with enhanced input signal processing. The driver/push stage pairs 1930/5171 and 5200/1943 devices in a compound-push arrangement, followed by 16 tubes in the power output stage, delivering up to 400W+400W output. Audio characteristics and topology: the board employs DC feedback design for clear analytical power, strong, detailed low-frequency performance and good elasticity. It is engineered to run stably at high power while maintaining responsive dynamics.