Seriously by changing the pickup pattern on a Large Diaphragm Condenser microphone to a Figure 8 and then placing that mic sideways near the 12th fret of an acoustic so the area of rejection is facing up and down you can record Vocals & an Acoustic guitar at the same time with minimal guitar spill into the vocal microphone! Plus because of the figure 8 Pattern you get some subtle room tone despite the mic being super close to the guitar! Then if you use a vocal mic with brilliant off axis rejection like say a Shure SM7B you will get minimal guitar spill into your vocal Mic! All allowing you to EQ the vocals & guitar separately!! It’s just pure brilliance, all of it!!

That is what I learned on my birthday!!