There is quite a bit of mangled info here, but mainly it is right info, but misunderstood.
A/B, ORTF, Blumlein, X/Y these are all distant microphone setups designed to create a realistic soundstage so I listener can close their eyes and point to the guitar, or piano, and perhaps have a good idea of who is closer or further away. Two mics close in are just two mics. They may be placed in a designated format, but that does not make them the title. All these designs incorporate changes in pressure at the diaphragm with or without differences in arrival time. Blumlein, for example would not be the term the BBC ever used when used to record 4 people with two mics. It was simply two fig-8 mics close together, NOT Blumlein stereo. The popular stereo techniques record the sound sources, AND the room. With close mics you are close in and the room sound is not really on the wanted list, as small rooms don’t sound nice, so close mics and artificial reverb sound better. Close mics also make panning more gentle, because voice right and instrument left, what you get with a stereo technique in close, is wrong and weird. It’s great you found mic placement that worked for you, just remember this is NOT a stereo technique but a solid studio one.
I’ve read loads of Alan Blumlein’s papers, and they are complex and full of maths. Even adding outriggers is damn hard to understand from the physics viewpoint. I’ve never seen the technique used successfully closer than the conductor.
