Help with calibration

[wheatenterrier]

I'm trying to calibrate the sound card on my sony vaio pc. The calibration went fine(I thought it looked normal. Then when I went to check by leaving the loop and taking a measurement this is what I got. Any ideas what's going on?

[wackii]

Try to extend your graph from 0hz to 20k hz.

Al,

[brucek]

Your plot is probably off scale. Be sure to run the Calibrate routine (button on the signal generator) and set the value to 75dB. Then your loopback measure will be shown at 75dB on the graph.

[wheatenterrier]

Thanks.
Here is another one. with your suggestions. Does this look ok? Which line should I be concerned about. The purple line is "corrected" the green line is the "target".
Again I am just taking a measurement with the loop back still pluged in. Checking to see if my soundcard calibration was appropriate.

[brucek]

Yep, it all looks good. The soundcard calibration file (dotted) has compensated for the soundcards inadequacies and returned a flat response for a cable (purple), as it should, since we know a cable to have a flat response.

The target line shown is for a subwoofer at a specific crossover that you have set in the left REW target panel. It is used to show how well your sub (when measured alone) tracks an ideal response. It is also used when creating filters for an equalizer.

Now you can remove the loopback cable and use that channel for your connections and measurements. Be sure to now load the SPL meter calibration file specific to your meter.

brucek

[wheatenterrier]

Great thanks. As I check the levels though I'm having to change soundcard settings from the way they were when I calibrated the sound card to get the levels right. Is that ok, or do I need to keep everything the same as when I calibrated the sound card?

[brucek]

Is that ok

It's required. You can't expect the signal through a cable loop to be the same as through a receiver and speakers and back through an SPL meter..

brucek

[wheatenterrier]

Sweet, you're a champ for helping me out.