Adaptations and improvements to tubular metal powder filters include employing cross sectional geometries of any suitable shape, aligning the inner conductor off-axis, replacing the inner conductive wire with a conductive trace or a superconductive trace carried by a printed circuit board, combining multiple filters within a single common outer conductive housing, and employing meandering and other non-parallel signal paths. The various adaptations and improvements are designed to accommodate single-ended and differential signaling, as well as superconducting and non-superconducting applications.