Volume Control Labeling and Audio Metering Labeling
Most car stereos, home stereos, and televisions control volume on a scale of like 0-10 or 0-100. However on professional audio gear all volume controls are labeled starting in the negatives at -∞ up to 0 then into the positives. This is because volume controls are labeled on how they are effecting the signal. For example is a volume control is at “-10db,” that means that control is taking away 10db from the signal. Volume control settings are relative to the signal they are controlling. Negative infinity is at the bottom to represent that the control is taking away an infinite amount of signal, so nothing is heard. Although the channel is not technically muted, it might as well be.
Audio Metering is similar. Audio metering is based around “unity gain” and is therefore relative to that. While initially it might make sense that audio meters would start at 0bd, then go up to some max like 120db or something. The problem with this is its not actually volume until it’s represented by something. So we have determined a universal “volume” that all audio devices recognize, this is “unity gain”. Volume meters are based around that. Negative db on a volume meter means that the signal is that amount of DB less than unity gain. Signal at 0 means that the volume is at unity gain, which is desirable, as all audio gear is designed to perform best in the unity gain area.