You may have seen guitar amps recorded with more then one mic at a time. This usually involves two different types of mics, like a dynamic and a condenser. The reason for doing this, is each microphone works in a different way and emphasizes different frequencies and other sonic characteristics.
If you’ve just started experimenting with using multiple mics to record your guitar amp, you may have run into a perplexing problem. When you combine the recordings from each mic, it sounds thin and anemic. Not the bigger, more complex tone you were hoping to get.
I ran into this problem years ago when I first started editing video. Often, a person on camera is recorded with two mics, a lapel mic pinned onto their shirt, and a boom mic, held just out of view of the camera. I wasn’t aware of this at first and thought the audio was just a stereo track. But it sounded terrible, very thin and quiet. I was ready to blame the sound guy, but looking at the waveforms, the volume seemed like it should be much louder. So I muted one of the tracks and it got louder and fuller. That made no sense!
So I asked one of the more seasoned editors if he’d seen anything like this. That’s when I learned about audio being out of phase. It can happen when two microphones recording the same source are at slightly different distances, or pointed in opposite directions. It’s a bit hard to explain what’s going on, but makes a lot of sense when you see it in action. Below is a video about exactly this problem and the simple way to fix it, put together by Graham Cochrane, from The Recording Revolution. It’s a great site if you want to learn to mix and record, and I highly recommend you check it out.
