Use of recording microphone and microphone placement method
It can be said that after knowing these basic operations, we can record. However, let’s put the software first, and then learn some basic knowledge. Because as a recording engineer, what you need to master is not just operating software, but also many other work in the studio. For example, we don’t know how to place the microphone, so we can’t talk about how to deal with the sound after it is recorded into the computer. Because we know that the microphone is the first step in the transformation of sound into electricity. The diaphragm in the microphone vibrates, turning the sound into an electrical signal. If there is a problem with the microphone itself, or the placement of the microphone, then there is also a problem with the sound you recorded, and it will be repaired by post-processing. So the first thing a sound engineer has to do is make sure that what goes into your computer is the perfect, correct sound. To do this, we first need to understand the most important piece of equipment for a sound engineer—the microphone.
The microphone is what we often call the microphone, transliterated as “microphone”, also known as the microphone. It is a basic device that picks up sound signals in recordings and converts them into electrical signals. It is arguably the most important recording device. Because no matter how advanced your sound card and computer are, if the microphone is not good, then everything will be in vain, just like the lens of a camera, no matter how high the pixel of the camera is, no matter how powerful the digital processing in the later stage is, if the lens is not good, the thing that comes in is itself. It’s blurry, so it’s no use. Ha ha. That’s it.
There are many types of microphones. The most rough division can be divided into three types: recording (broadcasting) and performance microphones, communication microphones and professional measurement microphones. Of course what we’re talking about here is the first.
According to the conversion method, microphones can be divided into electric type (including moving coil type and belt type), capacitive type (including electret type), electromagnetic type, piezoelectric type, etc. Of course, there are other ways of division, such as division according to the force of the diaphragm, direction, wired and wireless, etc. Actually none of this matters. The microphones we use for recording are generally dynamic and condenser.
Dynamic microphones are the most common type of microphones. It’s what’s in the karaoke room. Ha ha. Its structure is very simple. There is a magnet in the microphone and a coil under the diaphragm. When the diaphragm vibrates, the coil moves in the magnetic field. Due to electromagnetic induction, an electrical signal is generated. It can be said that dynamic microphones are the most widely used microphones, mostly handheld, so they are mostly used in performances. Of course, it is also often used in recording.
Generally speaking, the price of dynamic microphones is relatively cheap. As a beginner, if your wallet is not very strong, you can first buy a dynamic microphone with good performance to practice. Moreover, the advantage of dynamic microphones is that the requirements for the recording environment are relatively low. Even if you do not have a dedicated recording studio, dynamic microphones can still record. But try to buy better quality ones, don’t think about them if they are too bad. Hehe, I think when I just graduated, I bought a computer and used the karaoke microphone that comes with the BBK VCD to plug it into the Live sound card to record. The effect is horrible…
If you have a little more money, I suggest you Or use a condenser mic for recording. At present, it can be said that almost all personal studios use condenser microphones for recording. The structure of the condenser microphone is different from that of the moving coil. It is made of a thin metal sheet as the diaphragm, and there is also a metal rear plate. When the power is applied, the two form a capacitor. When the diaphragm vibrates, the distance And the plate is constantly changing, and its capacitance also changes, which produces a changing electrical signal. Therefore, condenser microphones require power to be used. Condenser microphones are characterized by high sensitivity, wide frequency response and good sound quality. It is the most commonly used microphone in professional recording.
The price of condenser microphones is generally higher, ranging from a few hundred yuan to tens of thousands of yuan. Obviously, the more expensive this thing, the better the sound quality. Which grade to choose can only depend on your pockets, huh, huh.
Picture: condenser microphone
There is a kind of microphone that we often deal with. It also belongs to a kind of condenser microphone, which is the electret microphone. The so-called electret is a kind of dielectric made after being polarized in a strong electric field, which plays the role of capacitance. If you don’t understand this, then let’s put it bluntly, haha, it’s the kind of thing used for voice chat.
Picture: Electret Microphone
This thing is extremely cheap, and of course the sound quality goes without saying: one word, rotten. If it’s a little bit professional, it’s better not to use it for recording. Of course, it doesn’t matter if you have fun.
In fact, in professional recording studios, there are often a variety of microphones, not one or two. The recording engineer will choose different microphones to use according to different needs.
Picture: Various microphones in the recording studio
There are generally some signs and switches on the microphone, which are used to set the direction of the microphone. In fact, these signs also represent the pickup direction of the microphone. Let’s talk about it below:
The circle-shaped symbol is omnidirectional. When this position is reached, the microphone can pick up sounds from all directions.
The sign of the figure 8 is bidirectional. In this position, the microphone only picks up the sound from the front and back of the microphone, and the side does not pick up.
The cardioid symbol is unidirectional. When this position is reached, the microphone only picks up the sound from the front.
The mushroom-shaped logo is also called supercardioid. It also only picks up the sound from the front, but the sound range picked up is very small, and only the sound from the direction facing the microphone is picked up. So it is also called super-direction.
Some microphones have only one or several directions, and many microphones have all the directions, which can be adjusted as needed.
Selecting a microphone, in a sense, there is no rule at all. It is impossible to say that this person is suitable for this microphone. There are many recording microphones on the market now, and the more expensive the better. However, this is not entirely the case, and in many cases, expensive microphones are not necessarily suitable. After the recording engineer is familiar with the sound characteristics of a microphone, he can use a certain microphone for a certain instrument or a certain person by his own feeling. In addition to looking at the electro-acoustic parameters marked on the microphone’s sound characteristics, the subjective sense of hearing is also very important.
Generally speaking, as a personal studio, you only have one or two microphones, and the recording is mainly based on recording vocals. Such a studio needs to choose one or two that can adapt to each Just use a microphone to record the sound. In a large recording studio, we need a variety of microphones to match. For example, when recording a symphony orchestra, facing a variety of instruments, we have to use different microphones according to different situations. At the same time, different instruments have different microphone placements.
Generally speaking, according to the placement of microphones, it can be divided into single microphone recording, dual microphone stereo recording, multi-microphone recording and so on. These are often encountered.
Single-mic recording, as the name suggests, uses only one microphone. Needless to say this. Stereo pickup requires two microphones to record. We have been emphasizing that one microphone is one channel, so the only way we want to record stereo is to use two microphones. Just like the two ears of a person.
There are many microphone placement methods for stereo recording, generally divided into AB system, XY system, MS system, head recording and OSS.
The so-called AB system is to place two microphones of the same model side by side, with a distance of tens of centimeters to about one meter, and then record.
The advantage of the AB placement method is that it has a good sense of presence, but the disadvantage is also obvious, that is, phase interference is prone to occur between the two microphones. We will talk about phase interference later. Therefore, this method has been rarely used.
The difference between the XY system and the AB system is that the two microphones are overlapped.
Generally, the angle of the XY microphone is 90 degrees. There is no time difference and phase difference in this arrangement, so the effect is better than AB. is a method that is often used.
Another commonly used stereo pickup method is the MS system. It is basically the same as the AB pendulum method, the difference is that it uses two types of microphones with different performances. One of the microphone spindles is facing the sound source, called M, and the other spindle is facing the left and right sides, called S. MS-based placement is almost completely free of phase interference, so it works best.
The M microphone above is unidirectional, pointing at the sound source, while the S microphone below is 8-point, picking up the sound on the left and right sides.
Picture: SM setup (front)
There is also a method called head recording, which is a very interesting recording method, which uses a human head The same size simulated human head, and two non-directional microphones were installed in the ears of the artificial head. The sound recorded in this way, if you enjoy it with headphones, will reproduce the sound field at that time very well. You can also hear everything that the dummy head “heard” at that time. The stereo effect created by this recording method is unparalleled. of. However, it can only be heard with headphones, not with speakers. Because only headphones can reproduce the position of the two microphones on the dummy’s head at that time.
Okay, let’s talk about some issues that need to be paid attention to when using the microphone. Some people may ask, what else do you need to say about the use of microphones? Connect the line, put the microphone there, let the singer sing to it, and it’s over? Ha ha… The use of microphones can be very particular! But generally speaking, the use of microphones is based on the experience and feeling of the recording engineer. Of course, there are some rules to follow in the use of microphones. Let’s talk about some knowledge about the use of microphones. These are also the most basic knowledge that a recording engineer should know.
1. When choosing a microphone, pay attention to the off-axis coloration and proximity effect of the microphone’s sound.
The so-called dyeing phenomenon refers to the excessive enhancement of a certain frequency band of the sound due to various reasons during recording, which has a lot to do with the recording environment, especially in small rooms without strong sound-absorbing treatment. Room prone to happening. In addition to the environment, there is also a certain relationship with the device itself. We know that microphones are directional, which is what we call axial. When using a microphone, the incidence angle of sound waves entering the microphone is different, and its sensitivity is also different. This is called “off-axis staining”. The axial frequency response curve of the microphone is of course the flatter the better, but in actual use, due to the different incident angles of the sound, the frequency will change accordingly, which will occur in any microphone.
Proximity effect refers to a low frequency boost phenomenon that occurs when the sound source is closer to the microphone. This phenomenon occurs with any microphone, but different microphones show this feature differently. You can try, recording farther away from the microphone, and recording very close to the microphone, the recorded sound is different.
Actually, the phenomenon of sound coloration and proximity effect is not a bad thing, but it can be a good thing if you use it. The key is what kind of sound we want to get. We can often see that some sound engineers deliberately let the singer “gnaw” the microphone, very close to the microphone, and the sound recorded in this way is very rich and magnetic. It’s not the same as being one meter away from the microphone. Maybe you would say, the closer to the microphone the better? of course not! This is just a situation, different singers, different microphones, different environments are different. Therefore, the use of microphones is very flexible when actually recording. It is important that you understand the characteristics of each microphone you have, the characteristics of your recording environment, and the characteristics of the singer, so that you can use the characteristics of the microphone to create the most perfect sound.
2, watch out for microphone overload.
Overload, also known as “recording and splitting”. This is a very common phenomenon. Even the most famous recording masters can’t guarantee that they will never hack when recording. Ha ha. When the recording is recorded, it is the nonlinear distortion caused by the sound signal exceeding the maximum sound level allowed by the device. And there may be many places to “crack”. For example, it is chopped in the sound card, or it is chopped on the stage, on the microphone, etc., and what is often overlooked by newbies is that the microphone itself is chopped.
Often when we are recording, we hear that the sound is broken, and the waveform displayed on the computer is “flat head”, but the amplitude is very small, and it does not reach the head at all. Then look at the mixer, the overload light on the mic preamp is not on, the input display of the sound card and the input of the Nuendo itself are not red. Where did it get cut? At this time we have to consider the problem of the microphone. We know that all microphones have a certain sound level tolerance. Generally speaking, the higher the sensitivity of the microphone, the lower the sound tolerance and the greater the possibility of overloading. Therefore, when recording high-level sounds, it is often more appropriate to use a dynamic microphone with poor sensitivity than a condenser microphone.
This is true in practical applications. For example, when we record the gongs and drums of operas in the studio, if we use a U89 for the gongs and drums, it is very easy to record and split, and the effect is not good if the microphone is far away. Well, at this time, it is better to use two SHURE moving coils, and the effect will be better. Suona and so on.
Many microphones have attenuator switches. When recording vocals, if you encounter individual treble overload, you can turn on the attenuation switch of the microphone.
3, pay attention to the impedance matching between the microphone and other devices
The signal from the microphone generally enters the microphone amplifier (commonly known as the microphone preamp) or directly enters the tuning (The mixer comes with a microphone preamp). Some are even plugged directly into the sound card (the sound card itself has its own microphone preamp). But have you considered whether your mic matches your mic preamp, stand or sound card? Because generally in professional recording studios, microphone cables are relatively long. Therefore almost all professional recording microphones are low impedance. The advantage of low impedance is that noise interference such as humming generated by the cable can be minimized, and high frequency losses are also relatively small. In theory, the input impedance of the input device should be the same as the output impedance of the microphone. In fact, this is not the case. The impedance of input devices such as mic preamps should be much higher than the output impedance of the microphone to allow for tolerance. Generally speaking, the output impedance of professional microphones is around 200 ohms, while the input impedance of professional mic preamps should generally be above 1000 ohms.
4, pay attention to the phase of the microphone
Here we have to talk about the concept of “phase”. Many beginners are always easy to confuse the words “phase” and “sound image”. “Sound image” refers to the position of the articulation point, such as the left and right placement of different instruments on a stage. “Phase” is a completely different matter. We know that sound is produced by the vibration of objects. Vibration is the rapid movement of matter particles colliding with each other and transferring energy in the form of forward-moving pulses or waves. A sound wave is a periodic motion, and the precise position reached by the sound wave in the periodic motion is called the phase. It is usually calculated in degrees of a circle. The starting point of any wave is 360 degrees away from the starting point of its adjacent waves, which means that all the peaks or troughs are in the same phase, and the peaks and troughs are opposite to each other, and the phase difference is exactly 180°. Add the same phase, subtract the opposite phase.
Generally, in a personal studio, we only use one microphone for recording, but when recording with multiple microphones, we must consider the phase between the microphones. Because the opposite phase sound signal will produce cancellation. For example, we often use two microphones to record a small chorus. When recording, we will find that although two microphones are used, the sound we hear is smaller and the sound quality is also deteriorated. This means that phase cancellation occurs. So what should I do, huh, generally there are buttons for phase inversion on the mixer and mic preamps, of course, it can also be done in software, we will talk about it later.
So what is phase distortion? Above we talked about the phase problem when two microphones are used. When recording a band in a professional recording studio, many microphones are often used to record at the same time, and the sound collected by these microphones is often out of phase. question. In fact, it also involves the interference of sound. When recording a band, different groups of instruments use their own mics, but in reality, when recording, there will always be instruments from other groups that go into the mics. Let me give an example. For example, when we record folk music, when the suona is blown, because it is very loud, almost all the microphones of the instrument group can record the sound of the suona more or less, some of which are direct, some are After being reflected, these signals will interfere with each other, sometimes resulting in a phenomenon similar to “comb filtering”, which distorts the sound. At this time, you will find that each track is not split, and the total output is not split, but the sound is very harsh and unpleasant. If you don’t know the acoustic reasons, you can’t do anything about this phenomenon.
Therefore, when recording, the production of this kind of sound should be minimized as much as possible. For example, use a soundproof screen, or make appropriate adjustments to the sound source, microphone and recording environment to avoid recording reflected sound as much as possible. You can even record interference-prone instruments separately. When recording, use the cardioid microphone as much as possible, and place the non-picking side of the microphone in the direction of the reflected sound. It should be noted that the soundproof screen should not be abused. Sometimes the soundproof screen will clutter the sound field, cause diffraction, and cause more serious comb filtering.
There is also a case of phase problems caused by unequal distances between the various microphones and the sound source. Phase problems may also occur if the distance difference between the different microphones and the sound source is equal to or close to an integer multiple of half a wavelength.
Actually, in recording, it is impossible to completely eliminate the interference between the microphones. There is a most traditional method in the recording industry called “three to one”. When recording, the microphone placement follows this principle, which can minimize the phase cancellation problem between the microphones. The method is simple: if the distance between a mic and a sound source is D, then no other mics can be placed within 3×D of this mic. This is the basic common sense that recording engineers know.
In addition, in a natural reverberation studio, the phase issue can be ignored. We will talk about the recording studio in the next lecture.
5, pay attention to the microphone cable
Some people may say, what is the point of paying attention to the microphone cable? Just pick it up! Oh, the cable has a great influence on the recording! Absolutely not to be ignored! Maybe your microphone and sound card are very good, but the sound is all ruined by a bad cable, especially the microphone cable.
We know that the electrical signal output by the microphone itself is very weak, and such a weak current is easily disturbed and produces various noises. Therefore, good quality cables must be used for transmission. First of all, the shielding of the wire should be good. In addition, the conductivity of the wire itself should be selected as well as possible. Many people may be willing to spend money to buy a good microphone and a good sound card, but they neglect to buy a good microphone cable. In addition, the power cord such as the power supply box of the condenser microphone must also be selected, preferably the one with a magnetic ring, otherwise it is easy to produce current interference sound. The microphone cable must use a balanced connection. Maybe if you change to a good microphone cable, you will find that the sound quality of your recordings will improve!
Recording microphones are different from performance microphones. They are generally more delicate, especially condenser microphones that are powered on. Vibration should be avoided during use. Vibration can overload the microphone and, in severe cases, damage components. Most microphones have shock mounts.
Before moving the microphone, it is best to turn off the power supply of the microphone and then move it, do not move it with power on. Because if the diaphragm vibrates strongly in a charged state, it may cause breakdown. If a condenser mic falls to the ground when powered on, it’s even easier to screw it up. Therefore, the microphone must be fixed well, and a microphone stand with better quality should be used. The microphone cable should be wound several times on the stand to leave a buffer before connecting to the microphone. The line on the ground must also be handled well, otherwise if you trip over someone, the microphone stand will fall, and the microphone will break, and you will cry…
7, try to use one microphone for recording
Multi-mic recording is unavoidable for recordings like bands. However, for the average personal recording studio, one microphone is enough. Moreover, now we only need to do a good job of sound absorption and sound insulation in the recording studio, as long as we ensure that the perfect dry sound is recorded into the computer, and everything else can be given by the computer.
Of course, the real master must use multiple microphones for recording, because dual-microphone and multi-microphone recording have many advantages over single-microphone recording. We know that the sound from the sound source is not unidirectional, and multiple microphones can pick up the sound in different directions, so as to obtain more perfect details. And a microphone can only pick up sound in one direction. I said before that 8 microphones record one erhu is the truth. Think about it, the sound of an erhu is sent out in all directions, and the eight microphones can pick up the sound details of all angles and directions. This kind of sound is undoubtedly more realistic than one microphone.
However, multi-microphone recording is also very difficult, which inevitably involves very precise microphone placement and post-processing issues. In addition, how to mix them into stereo after recording involves a lot of acoustic knowledge. , it can’t be used for granted, otherwise it will be self-defeating, and the recording will be more ugly! Ha ha. So, if your level is not high enough, it is recommended not to use dual microphones or even multiple microphones for recording, honestly and practically use one microphone to record first…
We will talk about so much in this lesson! Hope to be helpful to you all. In fact, there is too much knowledge about recording, and too much knowledge is needed. In addition to the basic knowledge of acoustics, it is more experience. So it is very important to learn as much as possible from the previous experience.
