Spaced omnis (ab)
By separating two omni directional microphones by several feet, the comb filtering effects that would be common in a spaced XY production would be less pronounced (apart from low frequencies). This quite accurately replicates a stereo image of the live performance. This is a relatively inexpensive way of recording a small sized stage but positioning of the microphones is crucial. As they are omnidirectional they will pick anything up 360 degrees around the microphone which includes the audience. It is important to align the microphones so that they are still pointing at the sound source as their most accurate performance is on-axis. In some situations a third microphone may be required for the center of the stage as it could be too wide. However, this could add additional phasing issues so if all it takes is a little tweaking of the existing microphones, then it would be best to use those.
The distance between the musicians and the microphones must be carefully adjust so that the desired balance of direct and reverberant sound is being picked up. If the sound is too ambient, then they need to be brought further forward. Conversely, if the sound is too dry, then the microphones need to be set further back. The slightest change of the position will radically affect the outcome so be careful not to move them too far. It is mainly a case of trial and error from this point.