‘ORTF’ is a non-coincident recording system that uses two cardioids with their diaphragms placed 17cm apart at 110 degrees. It was developed for French Radio (originally Office de Radiodiffusion Télévision Française, hence the acronym) in the 1960s.

The ORTF recording technique is a common staple for recording nature and ambience sound effects, creating a slightly larger stereo spread than the XY technique. ORTF is more susceptible to phasing issues when mixed down to mono.

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