Recording Tips: Acoustic Guitar Microphone Tecniques

Right behind voice, acoustic guitar is one of my favorite sounds to record. The sound can be extremely complex and is governed by so many factors that it is actually very easy to experiment with. In sticking with the basics, this installment will focus on micing up an acoustic guitar. I will share with you my favorite techniques and give you some general “rules of thumb”.

Before we get into micing up the guitar, I want to share and stress a lesson that I have learned many times over. The overused saying, “fix it in the mix” should be thrown out the window and replaced with another often-used saying, “garbage in, garbage out”. The goal should always be to capture whatever sound you are recording in the best possible way. When looking at recording acoustic guitar, consider the variables that can be optimized prior to setting any levels. To many of you, this will seem like common sense, but I cannot tell you the number of times that I have had to “gently suggest” this to musicians. First, replace the old strings on the guitar with new ones. New strings will drastically change the tonality of the sound. Next, please make sure the instrument is tuned. Finally, have extra strings, picks and anything else that is unique for the instrument handy. Nothing kills the energy of a session faster than having to run up the road to the store to buy a new set of strings because one broke on the perfect take.

Now that you’re ready to play, let’s mic the guitar. Condenser mics are usually the best choice for acoustic guitars due to their ability to capture the higher frequencies. I usually favor a large diaphragm condenser if I’m only going to use one (which I almost never do). If I were to do what most people new to recording would do, which is to place a single microphone facing directly at the sound hole, I would find out that the sound would be very resonant and bass heavy. This sound is probably not the sound that you are going for. This sound is often more desirable, however if you are using multiple microphones to capture the entire sound of the guitar. So in a single microphone set-up, you will want to place the microphone between the sound hole and the 12^th fret facing the guitar. Sometimes, when using only one microphone, I will place the microphone approximately at the 10^th fret facing back toward the sound hole. This gives a good mix of body from the sound hole and brightness from the neck.

More typically, I’ll use three mics for acoustic guitars for the reason that the instrument will sound very different depending on where the mics are positioned. I still begin with a large diaphragm condenser microphone, but this time I place it directly in front of the sound hole approximately 10 inches away from the guitar. This microphone will serve as the device to capture all of the body and resonance of the guitar. Next, I will set up a small diaphragm condenser at roughly the 10^th fret to capture the brightness and higher frequencies that the instrument is producing. Finally, I will put a third condenser microphone over the player’s right shoulder (if they are right handed, left if they are a lefty), to capture the sound that they are hearing. This microphone to me is the most important because you are hearing the performance the same way the guitarist is and it captures a much more “true-to-life” guitar sound. I will interchange large and small diaphragm mics depending on the performance style. By using three separate microphones to capture the performance, you will then be able to blend them together to get a very clear and accurate sound when mixing.

One word of caution regarding the multiple microphone technique; you will encounter phase cancellation if your microphones are not placed very close to the same position and there is a delay time between the microphones. As long as you are using 3 separate tracks, you can adjust to this while mixing, but as a best practice, try to keep the mics to a very similar proximity to the guitar.

The final mic technique for acoustic guitars that I will share with you is XY pattern micing. I use two small diaphragm condenser microphones with the capsules one on top of the others and one pointing toward the sound hold and the other toward the neck of the guitar. I generally place these microphones 6-10 inches from the guitar with the mics positioned right between the neck and sound hole. I pan them hard left and hard right and record. This creates a very nice and ear pleasing stereo effect blending the dark sound from the hole and the bright sound from the neck.

There are, of course, numerous ways to mic acoustic guitars, these are just a few. The best thing to do is move the mics around until you like what you hear. Try adjusting the height and angle of the mics as well as moving them up and down the guitar. Remember, recording is very subjective, find what sounds best to your ears and record it!