Does your acoustic guitar recordings sound like you put strings on a box? Or does it cut through your ears like fingers on a chalk board? Read on dear friend, you are not alone.
The first thing to remember when recording a guitar is the tone of the instrument itself. If it sounds like a box by itself, you will have to work hard to get it to sound decent in a mix. We’ll talk about how to do that in a bit.
Guitars have two resonating plates, the front and the back. Those will generate the sound together. Most often the top is thinner than the back, so more top end will project forward. The hole in the middle is essentially a ”bass port” extending the frequency spectrum downwards, helping the lower frequencies to move. Just like in a pair of ported studio monitors!
The strings will force the body to vibrate and the air flowing inside will generate sound. Good strings will make the body vibrate more and bad/old strings will have lost their tension, which will lessen the vibrations and the sound coming out of the guitar.
The first thing to do is make up your mind about how the guitar will fit in the mix. If it’s only a guitar playing it will go in the center, and filling the space between the speakers. But if it’s a small part in a groove with drums and bass it can’t take up that much space, but needs to be smaller and more focused sounding.
Standard microphone techniques:
X/Y: this is when two mics are placed at a 90 degree angle, with the membranes as close together, pointing at the guitar. This will give a clear center with no phase issues and still some sense of stereo.
Mono: One microphone. Gives a smaller sound that is perfect for a dense mix. No phase issues, and no trouble. Just aim and shoot.
A-B: This technique is using 2 microphones but placed further apart with the ratio of 3:1. For every 1 foot from the guitar, the mics should be 3 feet apart from each other. This will give you a huge stereo space but it will feel weaker in the center. Perfect for a wide accompaniement featuring a vocalist placed in the middle for example.
Where to place the mics?
Placement is very much dependant on the genre and the room you are recording in. If you want a natural sound, generally speaking you would want to back away from the guitar a bit and if you want a modern close up sound the mics need to be closer to the guitar, to pick up more detail and high frequency content.
Placing a mic further away will also pick up more of the room and depending on how well it sounds this is either good or bad. Try recording in as large of a room as you can as a general guide. Smaller rooms without treatment can sound boxy.
Placing a microphone closer to the neck will bring out more top end and string sounds. Great for strumming guitars and detailed melodies. Closer to the body will give a warmer mellower tone.
When using two microphones you can get the best of both, by placing the mics correctly. Then you have room for adjustments later on by balancing the microphones for either a brighter or a mellower tone.
There is thousands of different mics to choose from. But use what you have or what you can get your hands on. Learn one to understand the next. Educate yourself in what that mic can and can’t do well and then go look for one that fills your needs. Don’t listen to what everyone else things. They are speaking from experience with their genre and their recording environment, not yours!
My personal favourite is the SE Electronics se4400a. It’s not a cheap mic to start out with, but it is neutral sounding, and very versitile with different polar patters and a pad.
Dynamic mics: these have a slow moving magnetic coil that picks up vibrations (audio). It works less good the higher up the frequency spectrum you go. This is great for removing pick noises and room sounds but it takes away some detail and prescence to the sound. Dynamics are great for loud sources like a cab because it can handle anything without breaking.
Condenser mics: these uses a plate of thin metal or plastic that vibrates like a drum head. This membrane vibrate very easily and picks up a lot of detail. It is also very sensitive and picks up everything that makes a sound in the room. Jeans rubbing against the chair, air con, room reflections etc.
There are 3 main different polar patterns to know about. They control how the microphone is picking up the audio.
Cardioid is the most common one and it picks up sound in one direction – forward. It’s kind of like a sphere coming out from the front of the microphone. There are different width of this sphere and the closer it is the less sensitive to anything that goes on at the side of the mic it is. But then it also starts picking up from behind, eventually forming a figure of eight pattern. More of that further down. Cardioid mics comes with what is known as proximity effect. This means that the closer to the source the mic is, the more it captures the lower freqencies giving the recording a bassier, boomier sound. Great for warmth if not overdone.
Figure of eight. This pattern has a sphere coming out of both ends of the mic. Front and back. It records as much behind the mic as it does in front. Great for capturing the room with the instrument. It does a great job at NOT capturing what ever is on the sides however. Which is great when there is a bass player next to the guitarist. 🙂
Omni: this pattern records everything around it. It does not suffer from the proximity effect and is very good for capturing ensembles or rooms.
Recording a bad sounding guitar:
When using subpar instruments you need to be creative. There is always a way to subdue the least attractive features. Placing the mic facing the back of the guitar to avoid a shrill sound. Or hang a piece of cloth on the mic. Maybe place it far up the neck to get less boom, or simply backing it off for a distand feel. There are also lots of ways to cover a bad sounding instrument up. Reverb and slight distortion comes to mind. Or cool delay effects. But choosing what to play to best bring out the good qualities of the instrument is the best and most foolproof way. Accept that the instrument has limits and work your way from there!