Home Theater Forum and Systems banner

1 - 3 of 3 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Good day,

I can't find an answer to the question how to deconvolve the exported impulse response using the sound card calibration in REW. From my experiments, it looks like by default REW doesn't do it. Here is what I tried:

1) Calibrated the sound card
2) Made a loopback measurement -- the FR is flat
3) Exported IR from this measurement (32-bit, normalize, no IR window, no min phase)
4) Loaded the IR wav file into Audacity, and used "Plot Spectrum..." with Rectangular window, 65536 FFT

The resulting FR plot shown by Audacity is not flat, and has the same shape as the sound card calibration curve. From this, I conclude that REW exported the IR of the original measurement, and didn't deconvolve it by the calibration IR.

I would like to see, whether it's possible to export IR in a way that compensates for soundcard non-linearity, so the FR of the exported IR would look flat in Audacity.
 

Attachments

·
Premium Member
Joined
·
6,711 Posts
REW doesn't apply the cal files to the IR, mainly to avoid boosting HF and LF noise due to response roll-offs. You can generate cal-corrected results by using the trace arithmetic A/B feature on the All SPL graph, though.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
Thank you very much John! I didn't know that trace arithmetic function even exists in REW, shame on me.

Indeed, after dividing in the frequency domain, REW generates a deconvolved IR. And as you have correctly pointed out, there are some ripples in the LF area, although they can be smoothed out a bit by windowing.

Here is, as an example, the spectrum of the deconvolved loopback measurement response, using "Welch" window in Audacity.
 

Attachments

1 - 3 of 3 Posts
Top