One of the earliest ways of producing a stereo effect using just two microphones was invented by the brilliant electronic engineer, Alan Blumlein, in the early 1930's.
It involves the positioning of two microphones or two microphone capsules one directly over the other, pointed at right angles to each other and facing the sound source.
A ribbon mic can pick up sound equally from front
Several single-unit stereo mics have been produced using this arrangement. Here are two available from Royer Labs:
The SF24, with built-in preamplifier,
and the SF12, without preamplifier. I have one of these, and have successfully recorded small and large ensembles using this excellent pair of matched ribbon mics.
A high quality, high gain mic preamplifier is most important, as the output level of ribbon mics is quite low.
Enjoy this sample of a Blumlein technique recording of a concert band, recorded some years ago at a public concert (mic placement was not exactly ideal, as you might imagine!)