Originally Posted by mogorf
Try the method described above Keith and compare it to "your way". Report back your findings please.
Sorry, Feri, it doesn't work the way you describe. The sound level displayed by the REW SPL meter when you press the red record button is dependent on having been calibrated to a known external sound level before it will display a proper value. Take this test, for example:
- I set the AVR master volume to a value of -14, which on my system produces an 80dB sound level at the MLP (I know this because I have been doing this a long time).
- I launch REW and make sure everything in Preferences is configured properly.
- I then launch the REW SPL, and start the calibration tone.
- The REW SPL meter is reading 63dB, so (according to your instructions) I enter 63dB into the SPL Reading Calibration box and click Finished.
- Now I run the calibration tone again, and this time the SPL reads 63dB. So, like your say, we have synchronized REW with itself.
- Now, since I know that the test tone is really playing at 80dB, I enter 80dB into the SPL Reading Calibration box, and click finished.
- Now I run the calibration tone a third time, and now the REW SPL shows 80dB.
So, how does the REW SPL show two completely different SPL readings, 63dB and 80dB, when the loudness of the test tone playing through the AVR has stayed the same? It's because the reading on the SPL is dependent on the mic being calibrated. Since I knew the tone was really 80dB, and calibrated REW properly, the SPL now reads 80dB, which is correct.
So, my friend, a very nice try, but your method involves circular logic (or circular calibration, as the case may be). An external SPL is still required for proper calibration. Thanks for sticking with me on this, Keith.