Acoustic Recording Techniques: Acoustic Guitar, Dual Microphone Techniques
If you haven't gotten a chance to check out the basics of recording acoustic guitar, go ahead and check out the first blog in the series HERE.
In this post you will learn 3 ways to get a solid stereo recording of your acoustic guitar using two microphones. Let's get started!
Spaced pair is a great choice of microphone setup if you want a super wide image of your acoustic guitar. This technique is best suited for condenser microphones. Here we have two small diaphragm condensers (MXL 551).
The microphones are placed behind the bridge and at the 12th fret of the guitar. The microphones should be about 12 inches away from the guitar. The microphone at the bridge should be angled slightly inward toward the bridge and microphone to the right angled in toward the end of the fingerboard.
Another good way to utilize this technique is to swap out the small diaphragm on the bridge side of the guitar with a large diaphragm condenser, much like a setup that you would find in the MXL 550/551R Recording Ensemble. This well help draw out more of the lower end guitar tone and would bring more body into your recording.
The tricky part about a spaced pair setup is dealing with phase issues in post while you are mixing. Just be sure to double check your signal phase when you are ready to mix your acoustic guitar recording! The next technique can really help alleviate this problem.
In the X/Y configuration you can still get a nice stereo recording of your acoustic guitar with the added benefit of your microphones always being in phase. This is because this technique places the microphone capsules as close as they possibly can be to each other.
For setting up this configuration, you want to place the center point of the microphones near the 12th fret about 8-12 inches away rom the guitar. You can place the microphones at a 90 degree all the way to a 120 degree angle depending on how wide you want the end image to be. Just be careful not to go too wide or else you will quickly lose the mid level frequencies from the body of the guitar that gives a great acoustic guitar recording its character.
This technique gives tighter control over your stereo image, but the next technique will give you even more control in the mixing phase.
The Mid-Side technique is the most complex when it comes to stereo recording your acoustic guitar, but has a great deal of end value when it comes to mixing. There are some steps that are very important to follow to achieve a great acoustic guitar sound with the Mid-Side recording technique.
For this technique you need two different types of microphones. The "Mid" comes from a single directional microphone like the MXL 551 small diaphragm condenser pictured here. The "Side" microphone is seen directly underneath the condenser. In order for this setup to work the "Side" microphone must be a ribbon mic or another microphone with a Figure 8 polar pattern. This ensures that both sides of the microphone are receiving a level signal from the acoustic guitar.
The two microphones should be placed as close to the center of the guitar that you can get them. A good bet is to place the microphones in front of the sound hole and 12 inches away from the guitar. Some people like to make sure the front (+ side) of the figure 8 "Side" microphone is facing to the left while the back (- side) is facing to the right, but this is just a personal preference. The most important part is that the null side (where it doesn't pick up signal) of the ribbon or figure 8 is directly facing the sound hole/same direction of the "Mid" microphone capsule.
To eliminate any phase issues between the two microphones make sure to place the directional "Mid" mic as close to your "Side" mic as possible without leaning them against each other.
Recording with this setup is just as straight forward as any other. Just make sure if you are using a combination of a condenser and ribbon microphone that there isn't any phantom power running to your ribbon microphone or else it could badly damage or destroy the ribbon as they tend to be very delicate.
When you import both files of your microphone's recordings into your DAW it should look like a normal 2 channel recording.
After properly labeling the regions your next step is to take that side recording and duplicate it on to another track. You can label them however you prefer, but make sure to pan one of the "Side" tracks all the way to the left, and the other track all the way to the right to accurately present what your ribbon or other figure 8 microphone recorded.
This next step is probably the most important. Because the polarity is opposite on the backside of your ribbon or other figure 8 microphone, you must match that polarity in your second "Side" track. If you don't the entire recording will just sound in mono. This allows the phase to correctly sound just as it was recorded.
The last step is just to achieve a clean workspace and workflow. Once you have phase inverted one side of your "Mid" microphone tracks, group them together into a summing bus or channel so that you can adjust the levels evenly between them. Experiment by bring the level of the "Side" microphones all the way down to zero. You should at this point hear just a mono guitar sound from your "Mid" microphone. As you bring the level up on your "Side" microphones you should hear a huge difference in stereo image. The more you mix in the "Side" microphones, the larger your stereo image will be. It's an amazing thing!
The great thing about the Mid/Side technique, is that when you only hear the mid microphone track, that is exactly what the mix will sound like if summed into mono. There isn't as much guesswork as if you recorded as a spaced pair or even X/Y configuration. You will know EXACTLY what the sound will be if played through a portable mono speaker or phone.
There are many many ways to record your acoustic guitar, but these basics are sure to help you get started in the right direction. Stop by again some time for more tips and tricks!
Stay well and create often,