I’m reading thru amp measurements done here and there, and often the terms get conveyed as ‘db’ losses or gains of voltage, I suspect. When the DB comes up, I am lost.@blindjim Decibels are a logarithmic expression. They are handy because our ears are logarithmic as well. Voltages and audio equipment in general are linear expressions, so sometimes conversion is needed.
1 decibel is the least difference the ear can detect.
3 db is a minimum easiest change in volume that we hear. +3db requires twice as much power, -3db is half the power
6 db is a doubling of voltage, not power. This can be a bit confusing!
10 db is what we perceive as 'twice as loud' and requires 10X more power
20 db is 100x more power. 30db is 1000x more power.
In amplifiers there is something known as 'golden decibels', an expression that comes from the radio broadcast industry. 3 db represents a doubling of power, and to hear any significant increase in volume you need 3 db, so this gets increasingly expensive and in amps, the more power the less likely it will sound like music. This is why speaker efficiency is so important.
Voltage gain can be expressed as a ratio and can also be expressed in decibels. Here is a handy calculator if you need to make the conversion:
http://www.sengpielaudio.com/calculator-gainloss.htm