Why dual miking is great for your guitar sound.

This has to be the most talked about techniques for recording techniques, but why is it used in all the studios?  What is the big deal?

In our music room, at home, we have tried recording our amps, getting the best sound for our loved song. It is difficult to assess how many of us managed to dual mic the amp for recording when demoing.

Chances are, not many. Maybe because of gear reasons (not having 2 different microphones of great quality), because of insufficient inputs on the soundcard, because of lack of time in setting up, but all of us know that in the legendary studios they dual mic the guitar amp.They have these incredible microphones at hand, rooms with acoustic so wonderful that the take sets itself straight away in the mix, they have time to tweak the amp’s placement in the room, to change the type of guitars, etc. and amidst all that they dual mic.

What you want to achieve when you record a track are width and depth. As the name is quite self-explanatory, width can be understood as the space the track will take in the final mix in terms of panning.
For depth, it is about looking at as a layer: is it just going to be as thin as paint or as thick as a wall?

When recording with a single mic, what we always get is precision. The sound appears very precisely at one spot in the mix. If you pan at 9 o’clock, there is no mistaking where the track is. But there is no width to the sound. This is where dual miking steps in. With two mics you can spread your guitar track more in your mix. You will lose in terms of the precision of where exactly the guitar is but it will wrap the listener depending on how much you spread it.
This is the easiest way to use dual miking.

Also by spreading your two tracks apart, you avoid phase issues. When the two tracks are very close in the panning field of your mix, you will notice the sound of your guitar changing drastically. And it might even become a bad sound. Thanks to the phase relation of one microphone to the other. Each microphone does not hear the amp the same way, they are not placed at the same location and the sum of both can end up being useless when you mix the tracks (no presence, too much bass or no bass, no definition,etc. )

The other use of dual miking is equing your guitar sound. For instance, SM57 has a nice grit, great mids, but they do not have great bottom end nor sparkling highs. A second mic can bring you all the missing parts and replenish your guitar sound to a sound that is closer to what your amp is producing.
Having two microphones does not mean you have to set them at the same level. When using a second mic to support the main mic, the level of the former will be quite far off from the latter. Muting it will show you what you lose and thus helps you in dialing it in.

It is also interesting to experiment with using very different mics in terms of technology and characteristics: dynamic and condenser mic, ribbon and condenser mic, etc. With its broader response, the condenser mic will complement perfectly for low and high ends where ribbon and dynamic mics will yield the mids you are looking for.