Calibrating the Soundcard..with xenyx802 in loop?

**hasse_swe** · **02-13-08, 06:26 PM**

Hi! new here...

i bought my self an behringer 8000mic+xenyx802 mixer/mic amp
now from what i read in the roomeq manual when doing the measure after soundcard cal.+ still in loop mode...it states:
"it should be flat to better than 0.1dB"

my isn't flat to 0.1dB.. mine is something like +/-0.1 to - 0.6dB over freq range?

i'm running the loop like:
behringer uca202 usb soundcard->mixer->uca202

why isn't it perfectly flat?...shouldn't rew calibrate it flat?
regards/Hasse

**brucek** · **02-13-08, 06:53 PM**

Can you show us your graphs (with a scale that shows the errors)? I can't comment too much until we see the results.

Is the problem down at very low frequency? Do you see wiggles in the low end below 10Hz?

If so, then you likely have a card with a very good low frequency response. To correct this in the final soundcard cal file, you need to extend the Impulse Response window so that more of the response is included. Extend it until it's a bit smoother and then save the file.

To do this, run the soundcard cal routine and get to the spot where you are about to click Finish. Don't click Finish, instead click the IR Windows ICON in the upper right corner of the REW screen. A popup will arise and it will show the pre-window as 125msecs and the post window as 500msec. Extend the post window longer, and as you do, you'll see the Frequency Resolution result lowering. Change the window to something like 800msec and click Apply Windows while watching your squiggles. See how it's smoother now? Just don't go too far. Hit Finish on the soundcard cal routine and save the file. Your measurements will be more accurate down lower now.....

brucek