The Zapco ST-1B is a high-power mono block amplifier designed to drive subwoofers with precision and strength. Built on a Class AB architecture and powered by a high-current MOSFET supply, it delivers 200 W into 4 ohms and increases to 300 W when connected to a 2-ohm load. This power is balanced by a signal-to-noise ratio exceeding 90dB and a frequency response ranging from 15Hz to 30KHz, ensuring that low-end frequencies remain clear and controlled with total harmonic distortion kept below 0.2%. To help you fine-tune the sound to your vehicle's acoustics, the amplifier includes several adjustable controls, such as variable input gain and a low-pass electronic crossover. You can further shape the bass response using the variable bass boost and a subsonic filter, while the 0–180° phase control allows you to align the subwoofer's output with your other speakers. The unit connects via RCA inputs and features a linear output for system expansion. Housed in a black heat sink chassis measuring 182×52×310 mm, the design focuses on thermal efficiency to maintain stability during extended use. This setup is well-suited for car audio enthusiasts who want a reliable, high-current source to bring out the full depth of their bass system.