Bias Hysteresis

A saturation/headroom gauge rendered as an analog tape deck's own AC-bias hysteresis loop instead of a bar or dial: a bright marker rides a closed H/B loop that is narrow and sharp at low drive and widens with rounded corners toward saturation at high drive, its own envelope breathing on a slower independent cycle so the loop's shape visibly changes across a five-second sample, not just the marker's position on a fixed track.