I'm just starting to configure the M-Audio Mobile Pre USB with REW 4.0 for the first time, using the analog RS SPL meter as the mic.
I installed the M-Audio drivers to my laptop fine, but when I run the "Calibrate Soundcard" function in REW I get strange results. The response has a severe ringing from 30 to about 180 hz of +/- several db, with a deep notch between 100 and 130 hz. It looks a little like what REW warns about in the help file as having a "monitor" function on, though the amplitude changes (not fm-like noted in the help file), and it totally stops ringing at about 180-200 hz on up to to 20 khz, with a slight expected rise above 10 khz. Repeat trials are similar but not the same frequencies.
I used a one foot 1/4" mono plug to 1/4" mono plug patch cable into the front panel "ch1 inst/line" input looped to the back panel "1/L output". I also tried the "2/L output" to the rear "ch2 inst/line" input. At this point I didn't have the SPL meter or the output to the subs plugged in yet.
Each time I adjusted the REW Sweep Level and M-Audio input levels to about -12db so had no headroom or low level warnings. Everything ran just fine until I looked at the sweeps.
What am I missing? Do I have some cable or setting wrong somewhere?
Tom
