Welcome to Day 17 of 31 Days to Better Recordings.

On Day 12 we talked about keeping it simple, and only using one microphone for each instrument. These limitations can force you to be more efficient and creative.

There are certainly situations, though, where it’s a good idea to use multiple microphones on a single source. I almost always use two microphones when I record acoustic guitar, for example.

Flashlight Mics

Some instruments are large (acoustic guitar, piano, drum kit); others are small (human voice, harmonica, kazoo). It can be helpful to imagine that your microphones are flashlights. Wherever the light shines, that’s where the microphone is picking up sound. For larger instruments, you may need more “light,” so multiple microphones might be necessary.

If you place a flashlight 2 inches from the 12th fret on an acoustic guitar, it will illuminate a tiny little area…it will hardly light up the entire guitar. When your microphone is that close, the recorded signal will sound a lot like that little section of the guitar rather than the entire instrument.

Most instruments are designed to be heard in their entirety. Imagine if your acoustic guitar didn’t have a wooden body, and only had a REALLY nice, 3-inch area of wood around the 12th fret. That would obviously sound horrible.

There’s a reason the guitar is created the way it is. If you shine your microphone on such a small area, you might be missing out on the overall tone of the instrument. (Not to mention you’ll have a heck of a time dealing with the proximity effect.)

The moral of the story? Most of the time, you want to record the instrument as accurately and naturally as possible, and sometimes this means using multiple microphones.

For more on this idea of stereo-miking acoustic guitar, read these two articles (FYI – “stereo miking” simply means to use two microphones on a source and pan them left and right to create a wide, natural sound, much like the way the human ears hear):

Mo’ Mics Mo’ Problems

As you might guess, if using one microphone makes things simple, using multiple microphones makes things more complicated.

You’ve got to worry about mic placement and preamp gain for EVERY mic that you use. That’s not a big deal, but with every mic you use, that’s one more thing you have to mentally keep track of.

It’s easy to set up a bunch of mics and just start recording. “We’ll figure it all out later,” you say to yourself. This can be a dangerous approach. Why? Because of phase issues.

Whenever you use multiple microphones, you need to make sure the microphones are in phase with each other. If the sound reaches one microphone a few milliseconds before the second microphone, when you play both tracks back, the recording begins to sound thin.

Why? Because this tiny delay between the two tracks causes phase cancellation. In other words, some frequencies are removed, so you don’t hear them.

Still confused? That’s okay. Have you ever heard a guitarist play through a phaser pedal? A phaser pedal intentionally takes the guitar signal, duplicates it, and puts the second signal out of phase with the original signal. It delays it by a few milliseconds, resulting in that classic, thin, “phasey” sound.

That thin sound can happen to your recordings when you use multiple mics.

My 2 pieces of advice?

  1. Listen, listen, listen. Spend a lot of time listening to the mics together before you commit anything to tape. Adjusting one microphone by just a half-inch can make a huge difference.
  2. Observe the 3:1 Rule. (I highly recommend reading that article.)

Day 17 Challenge

Your challenge for today is to try using two or more microphones on your next recording session. How did you like it. Do things sound better or worse?

If you have used multiple mics before, tell us what you think. Do you like it? Why or why not?