A handy reference source for stereo imaging and mic setups.
The SRA is not the angle between the microphone axes, but an invisible angle, that gives you information about your stereo image. It tells you how “wide” the recording will sound. Every acoustic sources that are outside of the SRA will be located full at “L” or “R”. So a smaller SRA will give you a wider stereo image. Everything inside of the SRA will find a place between the left and the right speaker.
A stereo image is always due to time-of-arrival and / or level differences between the left and the right channel.