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Problems calibrating external sound card

1433 Views 9 Replies 2 Participants Last post by  brucek

I am just getting into REW & bought a BFD recently. My problem is when trying to calibrate my new external USB Sound Blaster x-fi sound card, I get an error saying volume level too low. I have it connected with the right RCA ouput into my receiver, one input to the mic and the other left input into th left output for the feedback loop. I can match the left ch ouput to the input that show on the graph. EAch reads around -3 but the right channel always read much lower, like -60 or so? So when I try and create the calibration file, there are no values in it and it wont save.

What am I doing wrong?

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What am I doing wrong?
Uncheck the 'Left Channel as Calibration Reference' checkbox. Remove all your cables.

Connect a loopback cable from the right channel line-out to the right channel line-in and run the soundcard calibration routine. Save the soundcard calibration file that is generated.

Remove the right channel loopback cable and use the right channel for your regular measurements. You will not use the left channel at all.

Does it look ok guys?
The soundcard cal file looks fine.

Now, for regular measurement graphs, use the following standard:

For subwoofers,
always use the standard Vertical graph axis of (45dB - 105dB) and the Horizontal graph axis of (15Hz - 200Hz) using the Graph Limits button in the top right corner of REW.

For full range,
use the standard Vertical graph axis of (45dB - 105dB) and the Horizontal graph axis of (15Hz - upper limits you desire, i.e. 1KHz -20KHz - certainly no higher than your soundcard can extend).
For full range only, enable smoothing to eliminate the comb filtering. Use a 1/3 octave smoothing.

Use a measurement start frequency of 0Hz and an end frequency of 200Hz.

Be sure to set your graphs to LOG and not LIN using the FreqAxis button in the top right corner of REW.

Always set a measurement target of 75dBSPL.

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I had the SPL RS meter calibrated at 75db when I did the sweep as well as the target level you mentioned.
Yes, but then the next step is to set the input level on the REW VU meter and then run the Calibrate SPL routine. This routine allows you to match the 75dBSPL actual level on your Radio Shack meter to the REW internal SPL meter that has no clue what 75dB is until you tell it...

Are you able to get proper levels when you install the loopback on the right channel and then run the soundcard calibration routine?

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