Sound card calibration

Steps to calibrate your sound device

  1. Be sure to have configured DRC123.
  2. Disable all other filter plug-ins, especially equalizers.
  3. If you are an expert you might also have a look at the extended calibration options page.

Method 1 - fast

  1. Connect line in of your sound card to line out.
  2. Select mode Stereo loopback (default).
  3. Press Run button.
  4. Adjust the volume to get a reasonable recording level. Note that volume changes discard the result.
  5. Wait until the results are reasonable smooth.
  6. Press Abort/Stop button.
  7. Enter a description to identify your sound device (optional).
  8. Enter a file name - without extension.
  9. Press Save button to save the result.

It is not required that the response is approximately at 0 dB as long as the result is smooth.

Method 2 - slower, more accurate

  1. Connect left line in of your sound card to left line out and right line in to ground.
  2. Select mode Left channel only.
  3. Press Run button.
  4. Adjust the volume to get a reasonable recording level. Note that volume changes discard the result.
  5. Wait until the results are reasonable smooth.
  6. Press Abort/Stop button.
  7. Connect right line in of your sound card to right line out and left line in to ground.
  8. Select mode Right channel only.
  9. Press Run button.
  10. Do not change the volume after step 4. otherwise the results will no longer match.
  11. Wait until the results are reasonable smooth.
  12. Press Abort/Stop button.
  13. Connect left and right line in of your sound card to left line out.
  14. Select mode Left to both channels.
  15. Press Run button.
  16. Wait until the results are reasonable smooth.
  17. Press Abort/Stop button.
  18. Enter a description to identify your sound device (optional).
  19. Enter a file name - without extension.
  20. Press Save button to save the result.

Troubleshooting

Input overdrive

If you do not get reasonable results in step 5, especially if the green and pink graph in the frequency response are noisy and graphs on the right show high and irregular values, then it is likely that you overdrive your line input.

Reduce the volume and repeat from step 5.

Equalizer enabled

If the frequency response is irregular but well reproducible (does not change with longer measurements) then most likely you have REALEQ or some other equalizer plug-in still enabled.

Disable all equalizers and other sound enhancement plug-ins except for DCR123 unless you want DRC123 to compensate for the effect of them. ;-)

Different Sound device

If the response decreases at higher frequencies with measurement time then you used another sound card for playback and recording. This causes the the frequencies of the test signal to be slightly shifted because of tolerances of the crystal oscillators of the sound devices.

DRC123 is not designed to work with frequency shifts because this would significantly decrease the accuracy of the results. DRC123 relies on several symmetries of the setup to get high precision results from cheap, uncalibrated hardware. The exact frequency is one of them. So it is essential to use the same device for recording and playback. This also implies that USB measurement microphones are unusable (i.e. Behringer ECM 8000) because they cannot support a synchronous playback channel.