a good guitar mic

There are many things on the market for micing a guitar amp. None used more often than the trusty sm57 shure microphone. It has been used practicaly ever since the electric guitar has been used. It has been on more guitar recordings than any other mic and has become the standard on which all other guitar mics are compared. It is made like a tank ,last forever and allows very large volumes such as a loud guitar cabinet to be used without harming the mic.
  I use one of these mics with my amp. Some people use these mics in combination with other mics. But i have found that it does a good enough job by itself.  Mic placemnet can make a big impact on what the mic picks up. In my mesa boogie rectoverb, it only has one 12 inch speaker so getting the mic placed correctly is important.  If you put the mic in the middle of the speaker you will get a very shrill high cold buzzy type sound -not recommended. If you put it at the edge of the speaker you will have warmth but will be too muddy. I recommend starting with it at the edge of the speaker but then angling it at a 90 degree angle to where it is pointing half way between the edgeand the middle of the speaker this will give you the best representation of what you hear with your ear.