A Decca Tree setup uses three omnidirectional microphones arranged in a "T" pattern outlining a triangle, often equilateral; the center microphone is mixed with the two spaced microphones to fill the "hole in the middle" in their imaging; it points the sound source. The placement can be done with three separate microphone stands or using one or more bars. In contrast to the ORTF stereo technique, the Decca Tree size is not fixed and may vary considerably; distances between the two back microphones are seen between 0.6 and 1.2 m; the front microphone is set proportionally and can be mounted slightly lower than the outside pair. The recording engineer arbitrarily adjusts these dimensions accordingly to the size of the ensemble, the dimensions of the room and the type of music. Microphone manufacturer Schoeps advises to put the three microphones at least 1.5 m apart to reduce crosstalk and excessive correlation at low frequencies (for example, setting the microphone width to 2 m and the depth to 1.5 m).