Microphone techniques: Guitar and vocal

If you have ever tried recording a singer who plays acoustic guitar you have probably encountered this problem. Because the guitar is in such proximity to the vocal source, seeing as they are being performed by the same person, there is alot of bleed between the two channels. Getting a good separation between the different sources is often a headache in these situations, where one wishes to process the vocal and the guitar separately.

The technique I am about to write about is extremely useful in these situations, and takes advantage of microphones with a figure of eigh directional pattern (more on this in another post). Different microphones have different directional patterns, meaning they pick up sound differently from different directions. A cardioid pattern is by far the most common and means that the microphone picks up sounds coming streight on much better than sounds coming from the back. Another pattern is the figure of eight pattern. As the name impies, this means that the microphone picks up sounds from the front and back, but rejects sounds from the sides (90 degre axis). Only the figure of eight pattern has a complete nullpoint, meaning a direction where it rejects 100% of all sounds, and this can be used very efficiently for recording an acoustic guitar played by a vocalist.

We start by using two identical microphones (ideally, though it will work with different mics) and place the first one in front of the guitar, and the second one in front of the vocalists mouth. When these microphones are angled so that their 90 degree axis' point directly at the other source they will effectively "null" it out. Now, placement is very important, as the level of separation depends on how accurately you have set up the microphones.

There will allways be some bleed from the guitar or the vocal of course, because we sadly do not live in a theoretically perfect world. The guitar radiates sound over a slight area, and to a larger degree so does the vocal. So there will always be some vocal and some guitar on the respective tracks. The separation however is much easier to work with and better, clearer results can be gained.

The figure of eight pattern is also incredibly useful in other settings as well. Lets imagine a kick drum, if a microphone is placed angling up towards thetoms and cymbals, this will hlp reduce the blled on the microphone, og a hihat mic for example, angled to eliminate the snare or the cymbals.

The possibilities are endles, playa round with them, and have fun!