Cleaning Microphones

Your school has finally invested in high quality vocal microphones for the studio and the student news anchors have never sounded better. Unfortunately, your lead anchor develops a cold and decides he wants to use your mic during his lead-in story.

You cringe as he practically yells into the microphone. You can barely watch as he reads his lead story with all the enthusiasm of Walter Cronkite. Afterwards he returns your mic, still operational but considerably wetter and unhygienic.

Microphones are subject to an inordinate amount of abuse, especially in live music. Grilles and foam windscreens can become saturated with saliva, clogged with lipstick, and will absorb the smell of cigarette smoke that can be picked up in off premise shooting. Regular cleaning of your microphone will not only improve its performance, but is also good hygiene. This article provides several simple yet effective techniques for cleaning microphones.

Dynamic Microphones
The best way to clean a microphone is to remove the grille. Most vocal microphone grilles simply unscrew. If the grille doesn't slide off easily, gently rock it back and forth while pulling it away from the cartridge. Do not pull sharply or with excessive force, since that could damage the cartridge or separate it from the microphone housing. Once the grille is removed, it can be thoroughly cleaned without damaging the mic. Since most of the offensive material on the grille comes from the human body, plain water should be a sufficient cleanser. Adding a mild detergent (dishwashing liquid) to the water will act as a mild disinfectant and remove odors absorbed by the foam windscreen. To remove lipstick and other material stuck in the grille, use a toothbrush with soft bristles. In some models, the foam windscreen can be removed from the grille, but this is usually not necessary since water will not damage the grille. For example, most Shure microphone grilles have a nickel finish that makes them resistant to rust, and replacing the foam windscreen can also be difficult and time-consuming.

The most important thing to remember is: let the grille dry completely before reattaching it to the microphone! Microphones don't like water, and although dynamic mics can withstand small amounts of moisture, a soggy foam windscreen will introduce more than is acceptable. Air drying is the best way to dry the grille, but a hair drier on a low-heat setting can be used. Care must be taken not to get too close to the grille as excessive heat can melt some windscreen material.

Cleaning must be done more carefully for microphones that do not have removable grilles. Using a damp toothbrush, hold the microphone upside down and very gently scrub the grille. Holding the mic upside down will prevent excess moisture from leaking into the microphone cartridge. This technique is also useful for cleaning the foam that covers the diaphragm inside some mics. Again, keep the mic upside down, and be very gentle.

In live situations with multiple acts, it may be desirable to clean the microphones between acts. Use a diluted solution of mouthwash (Listermint, Scope) with water. Using a toothbrush and holding the microphones upside down, scrub the grille of the microphone. At the very least, this technique will make the microphones smell more pleasant to the performer. Also make certain the sound system is turned off before the cleaning begins!

Condenser Microphones
Due to the more delicate nature of condenser microphones, never use water or any other liquid for cleaning purposes. Even a small amount of moisture may damage a condenser element. For microphones with removable grilles the grille and foam windscreen may be washed as described above. Again, the grille and windscreen must be completely dry before reattaching it to the microphone. To clean a microphone with a permanently attached grille, use a dry, soft bristle toothbrush and gently scrub the grille. Keep the microphone upside down so that loosened particles fall away from it. Take care not to let stray bristles get caught in the grille. This technique also works well for lavaliers and miniature gooseneck mics.

For condenser microphones that will be subject to harsh conditions, such as vocals and theater applications, it is advisable to use a removable external foam windscreen. This will protect the microphone from saliva and make-up, and can be removed and cleaned with soap and water after the performance. Remember, never get water near a condenser element!

For more information contact the manufacturer of your mics.  This information provided by Shure, a leading manufacturer of audio equipment. 

Reprinted with permission from Shure, Inc. All Rights Reserved