glossary
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Balanced
and Unbalanced:
Unbalanced cables are aerials. They'll pick up noise from any moving metal object, taxi, airport or commercial radio transmission within range. Unbalanced is two wires. signal+ and Ground. In order to remove noise, the balanced cabling system was devised. Like all clever ideas, it's really quite simple. Three wires. Ground, Signal+ and Signal-- (opposites) Any noise picked up along the length of the signal+ wire will also be picked up on the signal-- (since they're right beside each other) When you get to the end of the cable, discard whatever's the same on both wires (the noise) and keep what's different (the signal). a Direct Injection box is a device which converts an unbalanced line-level signal from a guitar or keyboard, to a balanced microphone level signal. There are two types of DI box, active and passive. Active DIs are more expensive and require a battery or phantom power, but passive DIs can pick up signals going through a hearing aid loop system. Feedback is the ringing or squealing that occurs when microphones are turned up too loud, or pointed in the wrong direction. It's not complicated. the sound coming from the speakers is being picked up by the microphone, amplified and sent back out through the speakers, where it's being picked up by the microphone, amplified and sent back out through the speakers... To stop feedback, move microphone or speakers so that what's coming through the speakers isn't being picked up by the microphone. Or turn the microphone down. directional mics reduce the possibility of feedback. Condenser microphones and active DI boxes need to be powered in order to operate. Phantom power is a DC signal (usually 48V) sent down the signal+ and signal-- wires of the balanced cable (relative to the ground or screen). The voltage doesn't affect the audio signal because it is the same on both + and -- wires, so it gets discarded by the mixer
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