—Microphones—

 

Quality starts at the source. Understanding how to track a sound is very important. We will begin by looking at microphones. While there are a few other types of microphones out there, we will focus on two commonly used types. The dynamic and the condenser. Both of these mics consist of a capsule with a diaphragm which is held taught and suspended in an aperture. The aperture is placed in a position where it can capture the sound and transform it into an electrically amplified signal. That signal is then sent to other devices which can alter or route the electrical signal where it needs to go until eventually, it gets converted back into an audio wave again by the speakers. The way the electrical signal responds to manipulation is virtually identical to the way audio waves interact and it is therefore an effective way to handle audio altogether.

The main difference between a dynamic mic and a condenser is the focus. A dynamic, the cheapest and most universally used, is capable of picking up sound quite well when the source of that sound is in close proximity to the capsule. The volume will, however, begin to fade as the source of the sound moves away from the microphone. There is a characteristic change in the sound’s frequency curve as the sound moves away and this is known as the proximity effect. The sound will typically lose some of its lower tones as the source gets further away. These dynamic microphones are useful for performing artists on stage because the sounds that are around the musician are not picked up as much as the vocalist, for instance, who is singing directly into the capsule. Having many of these microphones on stage DOES present an audio problem of having too many highs bleeding into the capsules from the surrounding area. Since the lower tones are not as prevalent because of the proximity effect we mentioned, it is usually a more challenging task to tame the highs of a PA system with an equalizer. In a stage environment, this is known as tuning the room. The act of tuning the room this way is a compromise between what the microphones are capable of doing and what the PA system sounds like in the room. Many factors come into play, such as:

the position of the microphones in relation to the speakers,

the position of the microphones in relation to nearby reflective surfaces, such as walls,

the quality of the microphones, and other sound equipment being used,

the number of objects or bodies that are in the room to absorb the sound,

and the kind of materials that make up the room. (For instance, cloth, wood, concrete, etc…)

Dynamic microphones are useful in recording studios as well and are used where the dynamic drop off and the proximity effect are either wanted or at the very least not going to be a problem. An example of this type of mic would be the Shure SM57, which shines on instruments, guitar amps and even certain drum pieces.

The condenser microphone is able to pick up sound at a much greater distance and is usually used solely in a recording environment where the ambient sound of the room can be controlled better. There have been major advances over the years with the technology of these microphones and they are now being used in both environments. The reason for this is the use of dual diaphragm capsules. Where the sound is being converted to an electrically amplified signal both, in front of the capsule, and also in the back side of the capsule. The use of creative signal routing within the microphone’s design, allows one signal to alter the other through the use of polarity switching. The result is the ability to focus the clarity and dynamic distance roll-off of the capsule by using polar pattern settings. These settings are varied more in the more expensive condenser microphones. The AKG c414 is one that has nine different polar patterns to choose from. Additionally, because condenser microphones are so sensitive, they are also equipped with bass roll-off switches so that nearby sounds will not cause too great an impact on the capsule at lower frequencies which by their very nature are felt more physically, and therefore, cause a greater amount of vibration. The measurement system used in categorizing microphones according to how much stress of this type they can handle, is called SPL, or sound pressure level.

NOTE: WHILE ALL MICROPHONES MUST HAVE THEIR OUTPUT AMPLIFIED IN ORDER TO REACH A USEABLE VOLUME, CONDENSER’S USUALLY REQUIRE AN EXTERNAL POWER SOURCE TO EVEN POWER UP. THIS IS KNOWN AS PHANTOM POWER.

 

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