Instruō dapf　

Introducing dåpf, the first dedicated effects processor in the Instruō product line. The Instruō dåpf is a set of two analogue all-pass filters.

You might be asking yourself, “What is the point of a filter that passes everything?” All-pass filters don’t actually attenuate frequency amplitudes directly but rather alter the phase relationship of frequencies across the spectrum. All-pass filter stages appear in the vast majority of voltage-controlled filter topologies as well as serving as a core building block within DSP.

The normalled I/O of dåpf allows for cascaded or independent use of the two all-pass filter circuits, offering everything from classic phase-shifting to psychoacoustic stereo enhancement and synthetic Doppler effect.

dåpf | (acronym) Dual All-pass Filter