重型机械启动

Heavy sci-fi machine spin-up, 400 ms. A 60 Hz sub-thump followed by a metallic turbine spooling from 200 Hz up to 700 Hz, with a short mechanical clank at the end. Sounds like a drill rig committing to a new depth. Dry, powerful, industrial. No reverb, no whoosh, no cinematic impact. Finish within the stated duration; do not repeat. Peak around -6 dBFS, no clipping.