Speaker Sensitivity Measurement at Set Power

V

Veleric

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If I want to measure my speaker's sensitivity at standard conditions (say 1 watt power) how do correctly set the power level? I know you can set the voltage level in the Level window on the measurement screen. But adjusting the volume control knob on my receiver/amp also changes the level independently. So I'm not understanding how I know I'm getting the intended voltage/power. Is there a calibration step that handles that?
Thanks,
Eric
 
Tim Hector

Tim Hector

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There are 2 standard ways to measure sensitivity. The first is to input correct voltage to produce 1 watt of power. Then measure the volume at 1 meter distance. Most companies have moved away from this process for a couple of reasons. Most on here probably knows that it requires 2.83 volts to produce 1 watt of power into 8 ohms or 2 volts to produce 1 watt into 4 ohms. To do this measurement as closely as possible you would need to impedance compensate most drivers to get a consistent impedance load. Then what if you end up with a 7.1 ohm or a 3.4 ohm load?
The more current standard today is to measure all speakers at 2.83 volts. Measuring this way gives you a reliable volume measurement across any speaker that any amplifier can reproduce.
 
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Veleric

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Tim,
Thanks, but I guess I didn't state my question clearly. That part I don't understand is how to ensure that when I make a measurment, I'm actually inputting 2.83 volts. I know that I can set the voltage level to 2.83 volts on the Measurement Level screen. But where I am confused is that at any REW level I choose, I can also change the volume knob setting on my AV Receiver. So I can set the level in the REW level field at 2.83 V, but with that setting fixed at 2.83 V I can change the output of my speaker from inaudible to blasting by turning the volume knob on the AV unit down or up. So it seems clear that setting the level in the REW level window alone doesn't fix the actual drive voltage at 2.83 V. How do I know what level my AV unit should be set at so that the level I set in the measuement field is the actual level getting to the speaker?
Thanks
Eric
 
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sm52

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Veleric said:
how to ensure that when I make a measurment, I'm actually inputting 2.83 volts
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Connect a voltmeter in AC voltage mode to the terminals of the device to which you are applying voltage. But not all voltmeters accurately indicate AC voltage at all frequencies. Therefore, it is better to apply the frequency of the alternating voltage that your voltmeter correctly shows. Next, adjust the level at the 2.83 V terminals using any regulators. Do not touch these regulators again. Further, during measurements, change the level only in REW.
 
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