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Did you really choose the right Microphone for your show?

Did you really choose the right Microphone for your show?
Issue Time:2019-08-23

Why that there are so many kinds of microphone? What is the best microphone? We receive those questions frequently in message.

First, we need to know is that there is no microphone can work for every event or occasion. It may be the best answer to the question ‘why are so much type of microphone in the market?’


Our ears are a very sophisticated and very complex sensor that converts sound signals into electrical impulses that are transmitted to the brain and our brains can resolve them into "sounds."Our ears are capable of converting sound signals from 20Hz to 20kHz.
Unlike our ears, the microphone can only accurately convert (and reproduce) sound signals in a specific range, usually this range is smaller than 20-20kHz.

If the microphone can be within a certain range, no increase or decrease the volume of reproduced frequency, we call this variable frequency range is "flat." When measuring a microphone, this item is called "frequency response”.For an engineer, this is a feature that must be known when selecting a microphone for a particular usage scenario.

Another feature to be aware of when selecting a microphone is the signal-to-noise ratio (S/N), which represents the ratio of the useful audio volume (S) from the instrument and singer to the noise (N) of the microphone itself. 

However, when choosing a microphone, the most important consideration is the type of design. There are currently two basic microphone types: dynamic microphone and condenser microphone.

Although dynamic microphones have always been the first choice for live sound reinforcement engineers, condenser microphones are gradually appearing on the stage of live sound reinforcement. For this reason, we will explain later.

Let's open the shell first and look inside.


Dynamic magnetic mechanics

Dynamic microphones can be divided into two types:  typical dynamic microphone and ribbon 
microphone.

The working principle of all dynamic microphones are electromagnetic induction: when two magnetics of different poles are held at a distance that is attractive but inaccessible, a magnetic field is generated between the two. In this magnetic field, there are countless invisible "magnetic lines".
In a typical dynamic microphone, a diaphragm is attached to the coil. The vibration of the sound causes the diaphragm/coil to move and cut the magnetic lines in the magnetic field. And then the induced voltage is generated in the coil. The vibration frequency is the same as the sound frequency.

In the ribbon microphone, a thin metal strip is suspended in the middle of the magnet. When the strip vibrates with sound waves, the magnetic lines are cut to generate an electromagnetic induction voltage. The voltage is conducted through the aluminum strip and is directly affected by the vibration frequency of the acoustic wave.
Dynamic microphone for easy movement

On the contrary, the typical dynamic microphone is extremely rugged. This feature is an overwhelming advantage for the band or live sound reinforcement. Not to mention the cheaper price.

Most dynamic microphones are single-directional—they only pick up the sound in front. This is an advantage for avoiding the "howling" which produce when the sound from the monitor speaker enters the microphone again.

The gravitational strength of the magnet, the number of coils turns, and the size of the diaphragm is equally important. Large-diaphragm dynamic microphones are generally more sensitive than small-diaphragm dynamic microphones.

Large diaphragms are often used when recording drums, except for snare drums. because the snare drum will produce a higher sound pressure level and emits an extra sound in the high-frequency band., it will also cause some damage to the large diaphragm microphone and cause distortion,in which case it would be better to use a small diaphragm microphone such as the SM57.
Some large diaphragm microphones, such as the Beta 52, are ideal for use on the kick drum. Also included is a bracket that holds the rim, eliminating the need for a bulky microphone stand that will make the stage cleaner and simpler.
If you are used to using the front-end wedge speakers as the stage to listen to, dynamic microphones are a good choice, they can increase enough gain, and can effectively avoid the occurrence of acoustic feedback. And if you're using an in-ear listening system, try using a condenser microphone to pick up the vocals or instruments. Although it may increase some budgets, it will get corresponding and better sound quality.
Use a condenser microphone on the stage

Condenser microphones are now also more widely used on the stage of live sound reinforcement. The sensitivity of the condenser microphone is very high, with a very flat frequency response in the range of 20Hz-20kHz.
The condenser microphone uses the charging and the discharging principle of the capacitor. The vibration of the sound drives the movable plate of the capacitor (ultra-thin metal film). The vibration of this plate changes the distance between the two plates (the other is the fixed plate). the change in the distance between the plates will result in a change in capacitance, and then the current of the analog sound signal is generated by a small electronic circuit in the microphone.

Unlike dynamic microphones, condenser microphones are not permanently magnetized during production. Therefore, phantom power must be used to power their diaphragms each time they are used. This type of power is usually transmitted through a microphone cable. The phantom power supply is typically a 48V DC power supply that meets the needs of large diaphragm condenser microphones.

The refinement classification in condenser microphones is called an electret condenser microphone. This design can use a smaller DC battery or phantom power, the voltage is much lower than the 48V required for a typical condenser microphone.
About phantom power

Phantom power supplies not only provide the necessary voltage to the board, but also power the onboard impedance transformer. Without a phantom power supply, the condenser microphone simply doesn't work. So where does this phantom power come from? In general, the mixer will come with phantom power.
However, To save cost, some consoles don't provide phantom power. In this case , the electret condenser microphone is the better choice. Both of PG-81 and HC-01 are electret condenser microphone.PG-81 is with a built-in Battery compartment .The HC-01 need to connect external battery compartment.
Since the condenser microphone sound is crisp and clean, many people like to use a condenser microphone when recording vocals. There are also many models designed for recording vocals. But one thing to note is that condenser microphones are more fragile than regular dynamic microphones, so it's best to give them a solid shock-proof box when used in a tour.

It is also important to note that acoustic feedback is more likely to occur due to the very sensitive capacitors. When using a condenser microphone for sound reinforcement, you need to pay special attention to the volume of the management stage. In this case, it is very necessary to use in-ear monitoring. In addition, you need to tell the singer to help them take appropriate countermeasures.

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