Why do high-performance amplifiers start from negative numbers for the volume control?

Question

You often see volume ranges from -70 to + 50 db - what does that mean?

Answer 1

The numbers on a receiver’s volume knob are referring to the "gain" on the signal. In almost all audio devices, there is an input signal (from your DVD player for example) which then goes to your amplifier and then your speakers. What the negative numbers mean, is that the signal coming into your amplifier is being made quieter before it is sent to your amplifier. For example, if your receiver reads “volume: -30dB” it means that the volume of the signal coming into the receiver is being made 30dB quieter before being outputted to your speakers.



So, of course you can figure out that the reading of “+0.00 dB” means that the signal is being made neither quieter nor louder before going to your speakers. Normally, with home theater systems, this level is quite loud.



A positive number (such as +10dB) is what is called “headroom.” Headroom is the ability of the device to make the signal louder before outputting to the amplifier. It is very unlikely that any home theater receiver will be able to have more then +10 or +15 dB of headroom. Wherever you saw the +50 reading is probably not an accurate gauge. Often times, on less precise equipment, the numbers mean almost nothing. Usually low end manufactures will use the + - dB scale so that the device appears to be higher quality, even if the numbers do not actually correspond to the appropriate levels.



I hope this was helpful.

Answer 2

I know this post is old but damn, dont comment if you have no clue and mix stuff together and thats even false!

Answer 3

in decibles its the rate of frequency or something like that like -20 is human speech i think and a gun is somewhere around 50db. just a reverse scale for sound waves and power of the signal.