A goniometer helps you to judge the coherence of the stereo image and determine phase differences between the left and right channels. Phase problems are easily spotted as trace cancelations along the center line (M—mid/mono).
The idea of the goniometer was born with the advent of early two-channel oscilloscopes. To use such devices as goniometers, users would connect the left and the right stereo channels to the X and Y inputs, while rotating the display by 45° to produce a useful visualization of the signal stereo phase. The signal trace slowly fades to black, imitating the retro glow of the tubes found in older goniometers, while also enhancing the readability of the display.
Because the Surround MultiMeter Goniometer is dealing with multichannel signals, the display is divided into multiple segments, as shown in the image. Each segment indicates a speaker position. When the surround panner is moved in a channel strip, the indicator changes accordingly. This indicates not only left and right channel coherence, but also the front-to-rear coherence.
Surround MultiMeter Goniometer parameters
Goniometer button: Show the Goniometer results in the main display.
Auto Gain field: Set the amount of display compensation for low input levels. You can set Auto Gain levels in 10% increments, or you can turn it off.
Note: To avoid confusion with the Auto Gain parameter found in other Logic Pro effects and processors (such as the compressors), Auto Gain is only used as a display parameter in the meters. It increases display levels to enhance readability. It does not change audio levels.
Decay field: Set the time it takes for the Goniometer trace to fade to black.
L–R, Ls–Rs, and Both buttons: Determine the channel pairs shown in the main display. When you are using Surround MultiMeter in configurations with exactly two channel pairs (quad, 5.1, and 6.1 configurations), the Goniometer can display both pairs if you select Both. One pair (for L-R) appears in the upper half of the main display, and one (for Ls-Rs) appears in the lower half.