This month: the final segment on the K Tube, covering the compensator.
The K Tube compensator allowed the Listener to detect the bearing of a sound source. As noted in recent Archives Notes issues, the triangular K Tube frame had a microphone at each point of the triangle. Two of these could be selected at a time by the Listener. Telephone receivers in the device converted the signals from the selected pair of microphones to sound, and directed one source to one ear and the other source to the other ear.
A hand wheel could be turned to lengthen the channel from one signal and shorten the channel from the other, slightly retarding the one while advancing the other. In the photo, the hand wheel has been removed to show the channels used for this purpose.
The Listener could finely tune the sound until a clear signal was heard, then determine the bearing of the sound source based on how far the dial had been turned. By taking two sound readings using different pairs of microphones, the Listener could figure the bearing of the sound source relative to the orientation of the K Tube frame; and a reading from the third pair could be taken to further confirm it.
— Todd Woofenden, editor