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Microphone Recording Techniques 101Aug 22, 2001 Write an essay on this topic.
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The Bottom Line You got to understand the basic's, and the more you know about microphones & how to properly use them makes all the difference.
How to reduce reverberation First let me describe what reverberation is. It is sometimes call “room acoustics” or “ambience.” Ambience is simply the sound you hear just after you shout in a gymnasium or a bathroom or even in your basement. Every building, home, bedroom etc. has it’s own “room acoustics” or “ambience.” Sometime this is good (read my articles on recording with ambience) while at other times it can seem like an awful plague from the devil! Too much reverberation or “ambience” in a recording can make the recorded instrument or voice sound distant or muddy. Here are some basic 101-type pointers that can help clean up your recording & eliminate un-wanted ambience & background noise. *Place the microphone closer to the sound source. For example: if you play guitar and want it as dry as possibly with out any room/ambience leakage at all, place the mic right on the front grill of the amplifier, aiming directly at the speaker. If you are singing and want to achieve the same thing, sing as close to the mic as possible, maybe even with lips slightly touching the windscreen/grill. *Use directional microphones. Here are the different types and there relative rejection levels in dB in relative to a “Omni pattern” at 1 foot from the sound source @ 1khz. Note Hypercardiod and Supercardioid patterns reject more “ambiance” than a Cardioid. Cardioid & Bidirectional patterns reject “ambiance” equally well. 1)Omni -0.0dB (not usually a good choice) 2)Cardioid –4.8 dB 3)Bidirectional –4.8 dB 4)Supercardioid –5.7 dB 5)Hypercardioid –6.0 db 6)Differoid -8.0 dB and @ 100hz it’s over –20db!(This is a patented mic from Crown International and works extremely well!) *Try using direct boxes or plugging instruments in “directly” with cables. (Sometimes this doesn’t sound the best with guitars) * Use a studio or room with dead acoustics. The walls, floor, & ceiling should be covered with a sound absorbing material. How to reduce background noise * Stop any background noise at its origin. Turn off appliances such as air conditioning, dehumidifiers, fans etc. * Try to use a dead/quite room. As Above *If possible try to seal doors & windows. *Wait for vehicles to pass. *If possible try to turn the sources volume up louder than any background noise. This is technically referred to a “signal to noise ratio.” * If possible try using baffles or recording booths or cabinets with doors. *Always aim the null of the polar pattern at the offending noise source. The null is the off-axis angle of the back of the microphone, which is the least sensitive. Different polar patterns have nulls at different angles. Here are the nulls in degrees. 1)Omni 0.0 deg. 2)Cardioid 180 deg. 3)Bidirectional 90 deg. 4)Supercardioid 125 deg. 5)Hypercardioid 110 deg. 6)Differoid 150 deg. How to reduce leakage First let’s define leakage. Leakage has also been called “bleed” or “spill,” and is the overlap of sound from one instrument into another instruments microphone. For example, if you’re miking drums and guitar in the same room with each having their own microphones and the guitar is picked up in the background with the drums mic’s this would be “leakage.” * Mic as close as possible with directional microphones. * If recording with multi-track recorders, if possible record each instrument one at a time. This is called “overdubbing.” * Try using direct boxes or plugging instruments in “directly” with cables. (Bass & electric keyboards work well this way) * Use a studio or room with dead acoustics. * Always aim the null of the polar pattern at the offending noise source. For example, if recording a snare drum aim the null of the mic at the high-hat to reduce high-hat leakage into the snare mic. *If possible try using baffles or recording booths or cabinets with doors (closets make great recording booths). Or lets say put the guitar amp in a totally different room as the other interments. Well this is about all I have for the basic’s part of this article. If you try to apply these basic techniques you will definitely will cut down a lot of un-wanted reverb/ambiance & leakage and produce better sounding recordings. But don’t forget that sometimes ambiance & natural reverberation can be useful. Read my other articles on that to find out why. Happy recording & good luck! Mark Darnell |
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