Iped,
Here for your consideration, is a list of some of the most popular methods used for what seems to be an endless search: miking an acoustic guitar for live performance.
The first ones listed are the most acoustic sounding, and are more prone to feedback. At the end of the list, are those that are more “electric” sounding, and therefore, less likely to feedback in a live situation.
1) External mic on a stand, preferably a large diaphragm studio mic: Sounds the best, will feedback at low volume. Very expensive, not used hardly at all in a live situation.
2) Mounted mic, near the sound hole. Sounds almost as good as live mic, feedback a little less, but useless in a band situation.
3) Mounted mic inside sound hole. Little less acoustic sound, because it is indeed inside the guitar, and there are all kinds of weird sounds in there, but still good. Feedback is minimized by the fact that it is inside guitar, away from loudspeakers. Still useless in band situation. Works well in solo work, coffee house setting.
4) Bridge plate transducer (LR Baggs “I-Beam”, K & K, etc.) sounds warmer, little less acoustic, but still maintains an acoustic identity. Amplifies entire top to get acoustic sound, will still feedback (but less than microphone), but can be controlled by an onboard or outboard E.Q. with a midrange sweep control.
5) Under the saddle transducer (UST): Has less acoustic sound, is getting its sound source from a very small area of guitar: the bridge. Can be used in a band setting, can get loud volume with out feedback. Is probably the most popular method with strict strummers.
6) Magnetic pickup located across the sound hole. Less acoustic sound of all, less feedback prone of all. Makes your acoustic guitar sound like a cheap electric, unless you use a good E.Q. with it to “sweep” the mids out. This pickup will just about sound the same whether it is on a 1941 Martin 000-45, or a Takamine, for the guitar it is used on loses some of its identity. However, it is the best unit to use in a band situation.
The best way to go, is to do what most pros do: a combination of any two of the above.
Good combinations:
One, is a magnetic pickup with a UST, and a blend control.
Two, a magnetic pickup with a bridge plate transducer, either a LR Baggs I-Beam, or K & K pickup.
Three, The IMIX, from LR Baggs, combines the Element (USP) with the I-Beam.
Four, the Fishman Rare Earth Blend, which, as the name suggests, blends a magnetic pickup with a gooseneck mic, inside the guitar. I use it, but the gooseneck mic is almost useless in a live situation. And it doesn’t sound all that great. I use mostly the magnetic pickup, and then dial in just a bit of the mic to get a more “live” sound.
Five, relatively new system by LR Baggs, combines the M1A magnetic pickup with an I-Beam. This would be my choice, over all the above.
Hope this helps. Good luck!