Home Theater Forum and Systems banner
1 - 3 of 3 Posts

·
Premium Member
Joined
·
1,400 Posts
I looked at your file ( and the following advice seems quite appropriate ) ;

Unplug your loop-back cable ( connected output to input // the one used to create the soundcard calibration ) & replace it with a microphone cable, plus a test mic ( both are then plugged into your soundcards mic pre-amp / see the pic below ) .

If the above seems like gobbley-**** to you, then you need to start back at the beginning ( by reading all the stickies / as well as available pdf help-files , such as the Help-File ) .

:sn:

 

·
Premium Member
Joined
·
1,562 Posts
I calibrate the sound card using a 1 ft cable. I then take a measurement using the same cable and I end up with a bad SPL graph.
What am I doing wrong?
Thanks for helping me out.
Your loopback measurement looks fine - only a couple minor points...

The reason the SPL is not flat is that the mic cal file is loaded. In the measurement panel use "Change cal.." to delete the mic cal only. The SPL will then be flat.

The phase looks wrong only because the polarity is inverted. Select the Invert box under "preferences/Soundcard". Any future measurements will be with the correct polarity.

Below is what it looks like after removing the mic cal for this measurement and Inverting the impulse and using "Estimate IR delay" in the Impulse panel. The IR was also just a little offset from 0 ms causing the high freq phase to curl up a little

Text Blue Line Font Design



You are ready to plug the mic in and take measurements.
 
1 - 3 of 3 Posts
Top