Signal levels

TVCA Audio Class #1	2. Conducting the Sound
Signal Levels
Mic, Line, Speaker and Other Levels

Audio signals cover a very broad range of levels.
The proper levels must be connected to avoid damaging equipment.

The two main aspects of signal interconnection are the level and the impedance.
The level measures the amplitude of the signal in volts (and in deci-Bels or dB).
The imipedance measures how strong the voltage needs to be to get the signal across.
Lower impedance signals are more "self sufficient" and are affected less by external noise.

MICROPHONE LEVEL
- Professinal Mics
  -60 dB (0.001v), 150 ohms
- Consumer Mics
  -65 dB (0.0007v). 2K (2,000) ohms
LINE LEVEL
- Professional Line Level
  +4 dB 1.5v, 600 ohms
- Consumer Line Level
  -10 dB, (0.7v), 10K (10,000) ohms
SPEAKER LEVEL
- +10 dB (5v) and higher!, 4 ohms
OTHER LEVELS
- Phono Level
  0.001v, 47K ohms, SPECIAL EQ!
- Mix bus level
  -10 to -30 dB, varies with mixer, WATCH LOADING!
- Headphone level
  Similar to low power speaker levels, ATTENUATE!

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