Measuring RMS Voltage: Many Meters Will Do
By Pat Brown
Pat Brown measures RMS Voltage using 5 difference meters and shares the results.
The Vrmsmax loudspeaker power test requires real-time measurement of the Root-Mean-Square (RMS) voltage of the noise stimulus. RMS measurements have been the subject of controversy since some variables regarding meter integration time, bandwidth, etc. exist. I have see excellent correlation between true RMS meters for noise signals. All meters shown here were used to measure 8Vrms of IEC noise during a recent power test on a line array HF element. The differential in measured RMS level between all of the meters is less than 0.5dB – adequate accuracy for loudspeaker power testing.
If the RMS voltage is still in doubt, I suppose one could use a thermometer. pb