Db level comparison

[Truett]

Still confused about proper level to set my audio system, (and microphone, I guess), when making measurements. I have attempted checking levels, and spl calibration, but it seems that it tells me not to worry about it since I am using HDMI and USB mic. I do have the calibration file for the mic loaded. Just not 100% sure I'm using the correct level, though. My Trinnov preamp is at -12 db.

So when I turn the volume up, I can make the frequency response graph move up. Turn it up again, and I can make the graph move up even a bit more. So when we look at frequency response graphs from speaker manufacturers, for instance, how do we make the levels comparable?

 

[John Mulcahy]

Unless you are measuring at very low levels, where noise becomes a factor, or very high levels, where compression comes into play, the shape of the response will stay the same as the level changes. Manufacturer data may be measured at some particular stated average SPL at 1 m. Passive speakers may be measured at an amplifier output of 2.83 Vrms (which produces 1 W into 8 ohms), the level will then depend on the speaker's sensitivity.