Miking

Microphone Placement

Room acoustics and microphone placement are the two key factors in getting a good recording. Two problems related to microphone placement are proximity effect and phase problems.

Proximity Effect

When recording with cardioid type microphones, be aware of proximity effect. Proximity effect causes an increase in the bass response as the microphone gets closer to the sound source. This often results in a boomy recording and care should be taken to avoid this by not placing the microphone too close the sound source. Proximity effect usually occurs when the microphone is within one foot of the of the source. Onmi-directional microphones do not exhibit proximity effect.

Phase Problems

You may of have heard of people referring to signals being in phase or out of phase. Phase is the timing relationship between two similar signals.

One way to visualize this, is to think of what happens when you play a monaural recording on your stereo. If your speakers are in phase with each other, which they should be, both speakers will move in and out with each other. If you were to reverse the wires on one of the speakers, then one speaker would move out while the other is moving in. This is known as "out of phase".

	Here are two sine waves that are in phase with each other. Both signals are rising and falling at exactly the same time. What you would hear when listening to these two signals is the sum of both.
	Since they are in phase, they will be added together to create a sound twice as loud as just one of them by itself.
	Here are two sine waves that are out of phase with each other. Notice that one is rising while the other is falling.
	If you add these two signals together, they will cancel out. This is what is known as cancellation.
	Two signals also can be partially out of phase. Notice that they are not rising and falling at the same time.
	This will result in a partial cancellation. This causes a decrease in volume when the two are combined. How much the volume decreases depends on how much the two signals are out of phase.

What these sine waves don't show is what happens when there are many different frequencies. If one of the signals is delayed slightly, some frequencies will be out of phase more than others. This means some of the frequencies will be quieter than others.

Listen to this miked guitar where both microphones are in phase.

Listen to them slightly out of phase. Notice that the sound is becoming thinner.

Listen to the two microphones where some of the tones are completely out of phase. The sound is much thinner.

Three things can cause phase problems to occur.

One cause of phase problems comes from using two different models of microphones. If one microphone has an opposite polarity than the other microphone, they will be out of phase with each other. Many preamps have a phase switch which allows you to invert the signal. This is the easiest way to solve the phase problem. Whenever you are using two microphones to record the same source, invert the signal of one of the microphones and listen for which phase sounds better. If you don't have a phase switch, you can usually invert one of them after you have recorded it, assuming you have recorded each microphone to its own track. Compare the two tracks after they have been recorded. If they have opposite phase, simply use the invert function in your software to invert one of the tracks.

Another source of phase problems is using two microphones that are at different distances from the sound source. This can cause the two tracks to be partially out of phase and usually results in a loss of sound quality. I use a couple of methods to solve this problem. One is to shift one of the recorded tracks so that it is in phase with the other. If you examine two tracks recorded with microphones that were at different distances from the sound source, you will see that the signal on one track is slightly ahead of the other. The one that is first is from the microphone that was closer to the source. Shift the other track back so that it lines up with the first one.

Another way to solve this problem is to pan the two tracks to the extreme right and left from each other. This produces a nice effect, but it makes it much more difficult, or even impossible, to control the position of the instrument in the mix. The instrument will tend to sound dead center.

A less common source of phase problems is having a microphone in front of and another microphone behind a sound source. Sometimes, engineers place a microphone in front of and behind a guitar cabinet, for instance. This also happens when you have microphones placed on both sides of a drum. This is a technique often used on snares. If the two microphones have the same phase, the recordings will actually be out of phase with each other. This can solved be using the invert switch on your preamp. Invert only one of the microphones, not both.

Miking Tips

Vocals

When recording vocals it is best to have a dead room. This gives you better control for placement in the mix. Add reverb in the mix, not while you are recording. If you record the vocals with reverb, you will not be able to remove it later if you find that you have added too much.

Your choice of microphone is going to depend greatly on your budget. Professionals will tell you that you should use the microphone that best suites the singer's voice. My advice is to get the best large-diaphragm condensor you can afford. Large diaphragm condensor microphones usually allow you to select different patterns. Normally, your will use the cardioid pattern or the omni pattern.

Always have the singer warm up before recording. This will help the singer's endurance and he or she will sing better. Many singers tend to become fatigued quickly in the studio. If the singer is experiencing vocal fatigue, either continue the session another day, or take a break. Once a singer starts to feel fatigued, the chances of getting a good recording are slim.

If possible, I recommend having a vocal coach available during recording. A good vocal coach can detect problems in a singer's performance and quickly correct them. If a vocal coach is not available, try to have another person, such as a band member, listen for timing and pitch problems.

I like to use some compression while recording vocals. I usually set the compression ratio somewhere between 2:1 and 4:1. It depends on the singer. I adjust the threshold so that I get about a 3 db gain reduction.

Backup Vocals

The same procedeure applies to backup vocals, except I usually use a dynamic microphone such as the Shure SM57. I prefer to pan the backup vocals to the center to give more of a chorus effect. The more you pan the backup vocals away from center, the more distinct they will be.

Electric Guitar

I prefer to record electric guitars by placing a single microphone in front of the guitar amp. The microphone is usually placed right up against the grill cloth. The Shure SM57 works very well for this. There are many good microphones for guitars, but for the price, the SM57 is tough to beat.

Placement of the microphone is very important. Generally, the closer the microphone is to the center of the speaker cone, the brighter the sound you will get. Moving the microphone to the outer edge of the speaker will give a mellower tone. You should experiment and find the best position for your recording. Getting a good distortion sound is often a real challenge. The tendacy is to crank the distortion way up during recording, but this often fails to work. If you are having trouble getting a good distorted guitar sound, try backing off on the distortion. What works for live performance does not always work in the studio. Another trick for getting a real full guitar sound is to double track. This means you record the guitar part twice onto separate tracks and pan them away from each other. Of course, the guitarist must be able to play the part repeatly exactly the same way each time.

I never use a compressor when recording electric guitars if it's played with distortion. Distorted guitars are usually already compressed enough. Clean guitars on the other hand may demand some compression especially if a rhythm guitar track is being recorded.

Acoustic Guitars

Acoutic Guitar Micing

My favorite type of microphone for recording acoustic guitar is a good small-diaphragm condenser microphone. I generally use one microphone placed about 18 inches away pointing to the area where the neck joins the body. If you get the microphone much closer, you will start to experience proximity effect and the guitar will sound boomy. I like to place the microphone a little low so that it is pointing upwards at the guitar. This gives a nice bright tone. Experiment with different microphone positions to see how it changes the sound. You can even add a second microphone and aim it at the bridge for a stereo effect. In this case, pan each microphone to the far right and left.

Ambient noise is a real problem when recording acoustic guitar. Acoustic guitars are not very loud, so you usually have to turn the gain up pretty high on the microphone. This means that you are more likely to pick up sounds other than the guitar. Try to find a very isolated room for recording acoustic guitar. I prefer to use a very dead room for acoustic guitars.

I only compress an acoustic guitar if it's being used for rhythm in a band. If the musician is playing solo guitar, I don't usually apply compression during recording.

Electric Bass Guitar

Bass guitars can be successfully recorded by either mike the amp or running the bass straight into a DI box. Many preamps function as a DI box. If you prefer to mike the amp, the same rules apply to bass guitars as for electric guitars.

If you are recording using a DI box, I would recommend using a compressor too. If you are mike the amp, don't use compression.

Drums

	Drums are one of the hardest instruments to record. I have a small room to record my drums. I try to make the room as dead as possible by hanging moving blankets from the ceiling around the drum kit.
	I use one or two condenser microphones overhead. If I am using two microphones, I place them right together and point them at 90 degree angler from each other. One is pointing to the right and the other is pointing to the left. This is know as the X-Y configuration. Put them as close as possible to each other to avoid phase problems. Some people position the microphones away from each other. The problem with this is that the sound from the drums arrives at the microphones at different times. This will cause some phase cancellation. You could use just one overhead microphone. This is the cheapest approach and will produce decent results. It just won't have any stereo imaging.
	I place the microphones in the center of the kit just high enough to be out of the drummer's way.
	I also use a large diaphragm dynamic microphone for the kick drum. The one I use is the AKG D112. Most people put the microphone inside the kick drum close to the rear head. This usually calls for some dampening using a towel or some other heavy cloth inside the drum. I prefer to place the microphone in front of the rear head close to the beater. This produces a sound with a lot of attack. Placing the microphone in front of the front head produces mostly a boom sound with little attack.
	In addition to this basic setup, I use close mikes on the snare and toms. For the snare, I use the SM57. This is a very popular microphone for recording snares. If this is the route you want to take, I recommend getting a drum microphone kit plus a pair of condenser microphones for the overhead.
	When close miking the snare and toms, try to keep the microphones a few inches from the drum head and point the microphone towards the center of the head. If you get the microphones too close you will experience proximity effect which will cause the drums to sound boomy.

I generally compress the overhead while recording. At least a 4 to 1 ratio works well, and I set the threshold for a gain reduction of about 6 db. I don't compress the other drums during recording; I usually do that in the mix.

Woodwinds (Flute)

Recording woodwinds is very similar to recording vocals. I usually try to avoid having the musicians breath aimed at the microphone. For flutes, I have found that having a music stand between the musician's mouth and the microphone very helpful. The rest of the flute should be in clear view of the microphone. I normally place the microphone about two feet from the flute, and I use a very dead room.

Stereo Recording

The main thing you need to look out for in stereo miking is phase differences. Make sure that the subject being recorded is the same distance from both microphones. If you are recording a group of some kind, use the X-Y configuration. If you are recording just one thing, then you can place the microphones apart from each other and point them at the subject. Just make sure they are both the same distance from the musician.

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