3000W Chinese Gensets Info.

Professor95 wrote:
Not quite (good pun!)

One db up is a 26% increase. If zero dB is equal to 1,000 microvolts, an increase to +1 dB is 1,260 microvolts. Another 1 dB increase is 26% of 1,260 is 328. Add that to 1,260 and we have 1,580 microvolts. Multiply that by 26% and we get 410. Add that to 1,580 and the sum is 1,990 (rounded to 2,000 microvolts). 2,000 microvolts is DOUBLE 1,000 microvolts. Thus, an increase of +3dB is in fact double.

There seems to be a lot of confusion about decibels. Let me say up front that I am not an expert on sound or how it is measured, but I DO know that doubling the distance is equivalent to a 6dB drop in the measured sound level. This is why I hate to see someone say "this generator is rated at xxx dB sound level" and don't make reference to the measurement distance.

However, I am somewhat of an expert regarding decibels when measuring electrical signal levels. (see my website) I work with a lot of instrumentation with units in dBm (decibels related to one milliwatt) and dBuv (decibels related to one microvolt). Some people have said that 3dB is double, others say that 10dB is double. In terms of electrical signals 3dB is double the power, 6dB is double the voltage. 10dB is 10x the power, 20dB is 10x the voltage. Why the difference between "power" and "voltage"? Power is voltage x current. If voltage goes up double, then the current goes up double as well (assuming a linear load) so power goes up as a squared function of either voltage or current.

FYI, 120 dBuV is equal to 1 volt. 140 dBuV is equal to 10 volts. 30 dBm = 1 watt, 40 dBm = 10 watts.

Electrical field strength also changes 6dB with a doubling of distance, so I think the sound level follows similarly the rules regarding electrical field strength. I suspect 3dB (in terms of sound level) will be double the sound "energy" while 6dB will be double the signal measured with a linear measurement device. How does this relate to the human ear?? I have no clue!!! :)

Not that any of this is important for selecting a generator!!! I just wanted to correct an error that I saw. I appreciate very much all of the great information provided by Professor95 and everyone else in this thread.