Microphone choices for Acoustic Guitars

Carrying on with the theme of popular microphone choices that many pros use for various instruments, this article will focus on various microphones commonly used to record acoustic guitars.

The choice of microphones and placement for recording acoustic guitars can vary quite a bit depending on the style of the music and the role that the acoustic guitar is going to play in the particular piece you are recording.  The guitar itself and the player will also have a much bigger influence on the sound than the microphones used.  To a lesser extent, the room where you record will also affect the sound to some degree.  Again, as mentioned in previous articles, there is no right or wrong way to do anything in this business… just trust your ears and do what sounds right to you!  But, having said that, by pointing out some of the more common microphone choices and techniques, perhaps I can save you a little bit of time when you are trying to record.

Let’s first examine some microphone choices and techniques for a typical supporting rhythm acoustic guitar part for a typical pop/rock song.  In this situation, the guitars are meant to be supporting rhythm elements only, and are often blending in with electric guitars or piano or other rhythmic instruments playing similar rhythms.  If it’s a fairly dense rhythm mix, you are usually looking for a bright and detailed acoustic guitar tone where you hear a lot of the strumming string noise to give the acoustic guitar even more of a rhythmic feel and to help it cut through the other instruments a bit more.  You typically would not want a whole lot of low mid body sound for this application as it will start to muddy of the mix with all the other instruments filling up that frequency range.

The “studio standard” first choice for this situation is a small diaphragm condenser microphone.  Probably the most popular microphones used for this in the bigger studios are the AKG-451 and the Nuemann KM-84.  The KM-84 is no longer made, and may be hard to find used even (as most people don’t let them go).  However, you can go with the modern replacement, the KM-184.  If you don’t want to spend that much money, almost any decent small diaphragm condenser microphone will work.  In my personal studio, I’ve had great luck with the no longer available Audio Technica AT-4031.  When I got my drum room set up, I also picked up a pair of AT-4041microphones, which are a step up from the old AT-4031 microphone, but they do sound a bit different (not better or worse, just different).  The next step up from those in the Audio Technia line is the AT-4051 microphone.  What makes the AT-4051 nicer, and more expensive, is that it has an interchangeable capsule, so you can have it be cardioid or omni-direction, just by swapping capsules (similar to what you could do with the “studio standard” AKG C-451 microphones).

To get that bright “strummy” sound, you would typically place the small diaphragm condenser microphone up on the neck of the guitar, pointing at about the 12th fret, and anywhere from a few inches to a couple of feet away.  You can also try it up higher, above the head of the guitar player, but still a bit in front of the guitar and pointing down at about the 12th fret of the guitar.  It all depends on the guitar, the player, and the room.  Be sure the guitar player puts new strings on to get that bright strummy sound!  If the sound is too bright, you can move the microphone towards, or just angle it a bit towards, the sound hole.  If it’s not bright enough, move it a bit more up the neck, or move it closer to the strings.  Be sure to listen to the sound in context to the full mix, though!  What may sound too bright on its own may not be bright enough in a full and busy mix!

Then, if you want that rhythm part to sound big and wide, you simply have the guitar player play the same exact part two times, and then pan one take hard left and the other hard right.  This natural doubling will give you that big wide and full rhythm guitar sound you hear on countless records.  You can’t simply duplicate one track and use delay or other tricks to get the same type of sound.  Real, natural, doubling gives a sound like no other method simply because of all the subtle and random human, and guitar, variations in timing and pitch.

For solo guitar work, or a song where the acoustic guitar is the main instrument, you may want to go for a bigger and more natural sound, and capture a true stereo recording of the guitar.  There are several methods to do this, with many choices of microphones.  One way is to use a small diaphragm condenser, exactly as described above, to capture the higher frequency “strummy” part of the sound, and then to place another microphone on the body of the guitar, aimed somewhere around the bridge, to capture more of the deeper tone of the body.  For this, a nice large diaphragm condenser microphone usually works well, and there isn’t necessarily one “standard” choice here.  I’ve used everything from a Neumann U-87 or U-47 (tube or FET) in the big studio, to less expensive choices like the Neumann TLM-193 or TLM-103, or Soundeluxe U195, or AT-4033 or AT-4050, in my own studio or smaller Seattle area studios.  All with good results.  As long as it’s a decent microphone, the particular microphone choice is not necessarily as important as finding the right spot for it and checking the combination of the two microphones for phase issues and overall balance.  Then, you would pan one signal left and the other right for a fairly natural stereo sound.

You can also use more conventional stereo mic’ing techniques to get a nice natural stereo acoustic guitar sound.  When the guitar is featured in this way, though, the sound of the room is very important in the overall sound.  A nice acoustically treated room with a great natural ambience and hardwood floors will give you the best sound.  You can use the X-Y stereo technique with two stereo matched microphones placed a foot, or more, directly out in front of the guitar (move them around until you find the best location).  Depending on the sound you are going for, this pair of microphones could be small diaphragm or large diaphragm condenser microphones.  If you wanted warmer sound, you could even use a pair of ribbon micropones.

Other techniques would be to use a spaced stereo pair of matched microphones out in front of the guitar several feet for a more ambient and wider stereo sound.  You could also have closer microphones set up, in addition to the stereo pair of microphones further out in the room, and mix them together to get the right blend of close sound and room ambience.  Again, nothing beats a great sounding guitar in a great sounding room, with a great guitar player.  If that’s not an option for you, then go for a relatively “dead” space with the microphones up close, and add in some ambience later.

One thing you typically do NOT want to do is to use the built-in pickups on acoustic guitars (if yours has one).  Those may be great for live shows, but the majority of pickups just sound horrible for recording.  There are a few exceptions, with some very expensive custom pickups that actually sound good enough to record, but using real microphones in front of the guitar, in a good room, will almost always sound better if you are going for a natural acoustic guitar sound.  In some cases, though, you may want to record the direct signal on a separate track, alongside the microphones, and possibly blend some of that in during the mix if you want even more of the string sound.

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