Optimized Cardioid Triangle, OCT

OCT is a surround sound microphone technique developed by Günther Theile and Helmut Wittek for the front microphone array. A cardioid microphone is applied for the center channel placed only 8 cm (3.1 in) in front of two directional supercardioids for left and right channels, pointing outwards. The spacing between the left and right microphones is the key to the desired recording angle. Distances between 40 cm (15.7 in) and 90 cm (35.4) are recommended by the designers, resulting in recording angles from 160° to 90°. One or more pressure (omnidirectional) microphones can be added to the system to compensate for the missing low frequency from the pressure gradient capsules of the cardioids. Example: The OCT2 variation suggests that the center microphone should be placed 40 cm (15.7 in) in front of the left/right microphone base line, giving longer time differences and spaciousness more like the Decca Tree.