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Discussion Starter · #1 ·
I am using a MobilePre USB and ECM 8000 in the XP enviroment. I calibrated the soundcard (MobilePre) with a mic cord and checked the calibrated measurement which was flat as a pancake. I calibrated it to 75 db using my Radio Shack SPL meter, and I got a popup menu stating that I could measure to 122db (seems insanely loud, way louder than I could ever measure with my Audiocontrol 3055). In the measurement menu if I select "check levels" I get the error message "level is low -62.3db". With the AC if you got the levels outside the window on the high side it would compress the whole display, giving you a false flat response.

Am I okay, and if not, what did I do wrong and how do I fix it?

Also, does this display output look okay for a first measurement? This is just a test graph to see if I have REW operating correctly.

graph1.jpg
 

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The problem is the levels the MobilePre is giving REW are very low. That is why you got a popup saying the limit was 122dB, because with levels that corresponded to 75dB going in you still had nearly 50dB of headroom. Redo the SPL meter calibration step, but while REW is waiting for you to OK the measurement increase the MobilePre mic gain so that the level shown on the SPL meter bar is around -20dB (or bring up the level meters and adjust the mic gain in the same way). Measurement looks OK, but S/N will be poor.
 

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Discussion Starter · #3 ·
I reset the volume as directed to about -20, which would just barely flicker the clip light. Gave me a target SPL of 97 (sounds much more reasonable), but I still have a “level is low” error at -42.9 when I rechecked the levels in the measure screen.

Can I live with this? Thank you so much for your help. I can’t describe how much I appreciate it.
 

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The result of a levels check in the Measure window depends on the frequency span selected and the speaker type being measured. It is probably OK, keep an eye on the headroom figure when you make a measurement and if it ends up higher than needed (more than 10 or 15dB, say) set the sweep level higher to use a bit more of the available range or turn the mic gain up a little further (but repeat the SPL meter cal if you change the mic gain).
 
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