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?

  • Hanzo S.

    I use Amplitube to record and although sometimes I experiment different cab settings for left and right rhythm guitars (both tracks recorded and not copied), most of the time I just use a different mic under the same setup.

    I would pan them around 80% L/R and set to mono, so far no issues for me.

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  • Because I mainly track drums, I always have at least 8 mics going at the same time. And I’m always experimenting with different things. One thing I’ve tried recently is to position my overheads behind me (instead of in front of the kit) in an XY pattern. This seemed to really bring the full kit to life.

  • Matt

    I’ve used both a single mic on acoustic as well as using two mics. If I have time and a patient guitarist, I will try to set up two mics. I usually put one near the 12th fret and one near where the arm comes over across the upper guitar body (to strum). That mic, I also put about 2 feet out in front of the guitar. Whereas the mic by the 12th fret is within a few inches of the guitar. While the guitar is being played, I punch in and out of mono to see if I have a phase issue. If I do, I usually move the mic that is on the guitar body (distant) until they are in phase. I also try to remember the 3 to 1 rule. If your close mic is 4 inches away from the sound source, a good starting point for your distant mic would be to be 12 inches away from the sound source. It works for me. I also have used one mic near the area of where the neck meets the body. I put it about a foot out in front of the guitar. It seems to sound pretty natural that way. Mostly, it depends on the player and the style being played. I do whatever I need to do to get the sound the player is looking for in that particular song.

  • Preshan

    I almost always use 2 or more mics on acoustic guitar. Matched pairs are great, but I find using very different mics adds more character and colour to the sound. Often I’ll use an LDC along with a pencil condenser like an NT5.

    Phase is something I always watch out for, especially when front and rear micing e.g. one pointing at the saddle and the other behind the guitar body pointing toward the soundhole, below the guitarist’s elbow.

    Often though, phasing can be used as an effect, especially on guitar cabinets – put 2 different mics in front of the cabinet, flip the phase of one and move them around. You’ll get all kinds of sounds that can give you lots of options.

  • The flashlight is a great analogy.

    I’ve used mismatched (cheap) mics in non-standard stereo arrangements with great results.
    If it’s not stereo it can be a pain to get things lined up. Hearing a loud guitar amp and trying to critically listen to your mic placement is tough. A phase rotating plug can really help. Muting one of those mics is sometimes the best option too.

  • Arjun Ramesh

    Great analogy about the mics being like flashlights, Joe. I never thought about it that way and it makes a lot of sense. I learned my lessons about stereo miking up close back in school. It sounded horrible, but I thought that it would give me a better sound by bringing me closer to the source. Boy, was I wrong! I really love miking acoustic guitars in stereo (XY) with a pair of pencil condenser mics. I have also tried miking them with large diaphragm condensers and sometimes they have a sound fit for the song, but I have a pair of mics that are my go-to mics for acoustic guitar and they really offer a natural sound, even for being kind of a no-name brand.

    By the way, Joe, do you find the Phase Scope plugin in Pro Tools useful? I instantiate it on stereo tracks just to see what it shows me. Do you use it often, or do you just listen to it?

  • Cush

    I recorded drums last night and I had the following set up –

    Inside Kick – ATM25
    Outside Kick – D112
    Top Snare – SM57
    Bot Snare – SM 57
    2 Rack Toms and Floor Tom – Beta 57 each
    Hi Hat, 2 Crashes, China, and Ride – C3000 Each
    Room Overhead – AKG C414

    This is definitely the most complicated Microphone set up I’ve done for a couple reasons. 1. This is the first session I’ve ran where I’ve had the resources to mic every part of the drumkit and 2. The drummer plays with a reeeaaalllly tight kit, so it took some creativity to get the mics to where they needed to be and still avoid excessive bleed. I also, obviously, had to worry about cymbals hitting mics and the drummer has to be able to play comfortably not not hit the mics.

    All in all, I spent around 2 hours setting everything up/patching/Setting levels/making sure everything sounded right. I’m really happy with how it turned out, and its amazing with the little bit of time I’ve spent mixing them how much more control I have over everything compared to other sessions I’ve done with limited resources.

  • Everett Meloy

    I did try using two microphones and somewhat happy with the result. It’s a lot like having a cupcake or having a cupcake with frosting. I need to work on it, thanks for the explanations; they provide helpful understandable information.

    • Just don’t put frosting on your microphones…

  • I use multiple microphones all the time. It might be a as a stereo-pair (I really like ORTF) or 2 mono microphones pointed at different points of the recorded source.

    While recording a guitar-amp, for example, I really like the sound of a ribbon (Nady RSM2 of GAP R1) mixed with that of a MD421/SM57. It takes some time to find the sweetspot with a condensor if you really are into finding it. But after that, it really adds nicely to the open and full sound of the ribbon.

    But, and this is really important, both mic’s need to have a great sound on their own. Because, while the combined signals sound great together when solo’ed, it might not be what the final mix needs! So, when you’ve put enough time on mic-positioning for both the mic’s, chances are on of them wil fit the final mix. The last thing you want is that your condensor sounds horrible on its own.

    • Condensor should be dynamic… Sorry for that!

  • Christopher w

    I used two mics on a snare drum on my last drum recording, one on the top and one on the bottom (flipped phase on one). it worked well especially with them panned very slightly apart.

  • Hector Gutierrez

    Ever since I became a member of the home studio corner website I started miking the acoustic guitar stereo mostly 9/10 times and for me it sounds so MUCH BETTER cause you really get to capture the whole dimension of the instrument. For me it sounds fuller and richer.. Also now Im starting to mic the electric guitar as stereo using one dynamic mic such as the 57s and then using a ribbon mic or a condenser mic to get that stereo image.. and I tend to do a bunch of overdubs to get that big fat sound…

  • Still saving up for a nice stereo pair of SDCs for acoustic!

    I still just use the one mic on my Acoustic (SE2200a) and it does sound nice, but has that narrow field that you’re talking about around the 12th fret area.

    I did, as an experiment, dual mic it once with the SE and my SM57 (the only other mic I have!) and it really did fill it out! At the moment I’m still recording demos/scratch tracks for songs I’m writing so it doesn’t bother me too much but when it comes to final tracking I definitely want to dual mic the acoustic!

  • Wayne Johnson

    I always use 2 microphones on almost all sources. I use two on acoustic and electric. If I record electrics I usually use the PZM in the room. Sometimes I use it in the mix and sometimes not. I like to record vocals with 2 mics @ 8-12 inches you just get a more natural sound. Just experiment to find what works for you and the sound your going for. Something I use in the room if you hear a sound you like place a mike in the approximate spot your ear hears it and move it around the area. It sometimes works but not always. Get the sound to start with,less work in the mix. Have fun and try crazy ideas the microphone. police will not show up at your door. Maybe your neighbors if it’s too loud though. LOL

  • Ben P

    I really love the idea of microphones as flashlights its a really good way if looking at it. I’ve found sometimes when I’m recording drums or acousitc guitars, that phase issues arent really a problem. Top and bottom snare is normally there but other than that, it normally sounds fuller leaving them as they are. Does this mean I’m doing I’ve been doingnit right all this time?

    • Possibly. I usually just set the mics up, try to get them roughly equidistant from a single point on the instrument. Then listen to them in mono (not panned). If everything sounds good, you’re good to go.

      It’s just important to be aware of phase issues, but that doesn’t mean you’ll always have them.