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    Microphone Basics

    Q: How does a microphone work?

    A: The microphone is the first link in transforming mechanical energy (sound) into an electrical audio signal. Without getting too technical, a microphone uses a thin diaphragm that is free to move back and forth in response to the pressure of the sound reaching it. Whereas, the microphone is the first step in the process, the loudspeaker is the last step, transforming an electrical audio signal back into mechanical energy, or sound.

    Q: What is the difference between Dynamic and Condenser microphones?

    A: Dynamic microphones are also known as “Moving Coil” microphones, and generate their signals by moving an electrical coil through a set of permanent magnets. As the name implies, the moving coil adds the burden of additional mass to the moving components of the microphone, making a dynamic microphone less able to respond to sharp changes in dynamics, or transients, and less sensitive overall.

    Condenser microphones, on the other hand, behave much like a large capacitor and require an active power source—either from phantom power, an external power supply, or a battery. There are also hybrid condenser microphones that employ a permanently charged backing plate, known as an electret condenser. In both case, the components in a condenser microphone combine to behave as a large condenser (or capacitor), converting the movements of the diaphragm into an electrical signal.

    Q: What type of cable will I need for my microphone?

    A: Generally, most microphones are considered Low Impedance (< 600 Ω) and are connected using a three-pin XLR microphone cable. These cables have a distinct Male and Female end. This type of cable can simultaneously provide phantom power to the microphone. High Impedance (>10,000 Ω) microphones often feature an attached cable ending in a 1/4" plug, similar to an electric guitar cable. The important takeaway here is that a Lo-Z microphone signal can travel a much greater distance with minimal sacrifice in audio quality or fidelity. With a Hi-Z signal, the signal quality will degrade (increased noise and the loss of higher frequencies) at about 20 feet. Lo-Z signals can travel much further, making them ideal for stage and studio use. Inline level matching transformers can be used to create the correct impedance level. Certain High-end studio microphones with a dedicated power supply often include their own specialized multi-conductor cable.

    Q: How does the size of the diaphragm affect the sound?

    A: Size matters, but bigger is not always better. Due to its increased size and mass, a large diaphragm (≥ 1") microphone will have warmer sound favoring lower frequencies and will generate a stronger signal output, thereby providing an improved signal-to-noise ratio and lowering the noise level for a cleaner sound. Large Diaphragm mics are therefore an excellent choice for recording spacious, warm, and natural vocals. However, a smaller diaphragm (≤ 1") microphone is more responsive to both dynamic transients and the faster vibrations of higher frequencies while minimizing low frequency interference. In addition, the smaller diaphragm is less prone to unwanted coloration of off axis-sounds. This makes a small diaphragm mic ideal for cymbals, acoustic guitar, brass instruments and the like.

    Q: How do uni-directional, omni directional, cardiod, and other pick-up patterns compare?

    A: The ability of a microphone to capture or reject sounds that occur in front of, to the side of, and behind the microphone is referred to as the pick-up pattern. Obviously, picking up sound in front of the microphone is always desirable. However, minimizing the amount of sound a microphone captures to the side and back can be important for eliminating feedback on stage, or for increasing isolation in the studio. But making a microphone too directional can require the artist to maintain a constant position, possibly limiting the performer’s motion and expression The most common pattern is Omnidirectional, capturing sound equally in a full circle around the microphone. Cardioid (literally “heart-shaped”), Hyper-Cardioid, and Super-Cardioid offer increasing degrees of back and side rejection to create a more uni-directional pattern. Shotgun and Figure-Eight are pickup patterns for special uses. Many advanced studio microphones offer switchable pickup patterns for maximum versatility.

    Q: Aside from the microphone and cable, what else might I need?

    A: That’s really up to you. If you plan to use the microphone in a variety of applications, having a fully-articulating and adjustable stand (such as a boom stand) provides the most versatility. To minimize vibrations and handling noise, you might want to invest in a shock-mount mic holder. Using a pop-filter and/or windscreen will minimize explosive “P” sounds and preserve the microphone by keeping exhaled moisture off of the diaphragm. Depending on the system you are connecting your new microphone to, you may want to add an electronic mic-preamp; a compressor-limiter to deliver improved dynamics; or an external signal processor to provide reverb, warmth, or other effects.

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