Originally Posted by Simonpink
how do you get these wattage measurements, Mike?
The wattage I mention is what would be applied into the nominal driver impedance.
I measure voltage applied to a known resistance, then it is just a math problem.
Watts = Voltage^2/Resistance
I have some 4-ohm load resistors that will handle ~150 watts each, so when I wire them into an 8-ohm load, I can directly measure drive voltage up to ~50 volts before the resistors get overloaded.
I've measured my test gear at 1, 10, and 100 watts, and found that adding 10 dB of drive in REW does result in the expected voltage increase. As a result - during a typical test sequence, I set the 1-watt level accurately, then just step up from there.
For an 8-ohm driver, I set the drive level to 2.83 volts measured with a 60 Hz sine wave into an 8-ohm resistance, with the REW signal generator at -30 dB. I swap the resistor for the speaker I'm testing, then set the mic at a meter and run my first sweep. This would be a 1-w 1-m sweep. Depending on what I'm testing, I either step by 3 dB, 5 dB or 10 dB increments in REW drive level, and run the next sweep. I have occasionally checked voltage at the 10 W and 100 W sweeps to be sure things are working right.