Mic troubleshooting

How can I troubleshoot mic problems, such as "the mic is dead" or "the mic makes strange noises"?

If your mic makes NO SIGNAL when you play, make sure that the mixer controls are turned up and signals are correctly routed in your mixer. If your mic is a condenser type, turn on phantom power. If the mic is still silent, try another good mic in the same channel, with the same cables. If the other mic works, send your silent mic in for service. If the other mic doesn't work, repair or replace any connecting mic cables or stage-box cables/connectors. 

Direct boxes might be powered BY phantom power, but they don't supply phantom power TO a mic. Preamps with XLR mic input connectors usually can provide phantom power to a microphone.

HUM is a low-pitched steady tone that does not change when you move the mic. Connect the mic directly to your amp or mixer. If you hear hum after you plug in the mic, return the mic for service. If the amp or mixer still makes hum when the mic is not plugged in, fix the amp, mixer, or connecting cables.

DISTORTION is a raspy, gritty sound. It is worse when your instrument is played loudly. If you hear distortion, get a mic pad (microphone attenuator) and plug it into the mic's XLR connector. Or turn down the GAIN TRIM knob in your mixer's mic channel just until distortion stops and the clip light goes out.

If you hear CRACKLING when you move the cable that is part of the mic, the cable needs to be repaired. Send your mic in for service.

HISS is a noise like wind in trees or ocean surf. If you hear hiss, set up your mixer for correct gain staging: 
1. While playing loudly, turn up the GAIN TRIM in the mic channel until the clip (overload) light flashes, then back off the gain trim about 6 to 10 dB. 
2. Set the mic's fader about 3/4 up, and set the master fader about 3/4 up. Then if the sound is too loud or you hear feedback, turn down the power amplifier volume as needed. 
3. The mixer meters should peak near 0 dB, and the power amp should be turned up only enough to get the volume you want.

Also, switch out any pads that are built into some direct boxes. Substitute another good mic and see if the hiss stops. If it does, send your mic in for service. 

FEEDBACK is a squealing sound that happens when the mic is turned up too high, or when the mic is too close to your amp or speakers. Feedback changes pitch and volume when you move the mic. To prevent it, turn down the volume, turn down the bass or treble, place your amp or speakers closer to the audience and farther from the mic. Use a graphic equalizer or a feedback notch filter in a preamp to turn down frequencies that feed back.

If the sound is too BASSY, turn down 100 Hz in your mixer's EQ section, or turn down the bass in your amp, or place your amp farther from the floor and walls.

If the sound is too BRIGHT, crisp, sizzling, etc., turn down 10 kHz in your mixer's EQ section, or turn down the treble in your amp.