REW Beta Release Clarification of response calibration

[Antonio Di Motta]

Hello John
I wanted to bring to your attention a possible problem about compensation for frequency and phase response.
On my test system consisting of a raspberry Pi4 with Audioinjector zero soundcard with REW 5.20 beta 27 version, by performing the calibration of the response a strange phenomenon occurs on the signal phase. In particular, the response is correctly compensated, while the phase is correctly compensated only at low frequencies, at high frequencies it is worse in compensated mode than without compensation.
I am attaching the image files and also the mdat and cal file to be able to do the checks.
Thanks so much

 

[John Mulcahy]

No cal file attached, but the rising HF phase will be due to differences in the t=0 position for the measurement versus the calibration. The calibration removes measurement delays, the measurement probably has t=0 at the peak.

 

[Antonio Di Motta]

Sorry John, but I had a lot to do and I didn't send you the cal file. I have re-done all the measurements and I send you all the files, only the calibration file I change the extension in .txt because otherwise you can't load.
Thanks so much

 

[John Mulcahy]

The explanation remains as I posted above, if you run Estimate IR delay on the measurement with the cal file you will get flat phase after removing the delay.

 

[Antonio Di Motta]

Sorry John, but I don't understand you, how can I estimate the delay in estimating the calibration file? I tried to load the calibration file and REW from this error:

REW V5.20 Beta 27 running JRE 1.8.0_231 32-bit on linux 4.19.86-v7l+, it, UTF-8


Message:
java.lang.ClassCastException: javax.swing.plaf.basic.BasicFileChooserUI$AcceptAllFileFilter cannot be cast to roomeqwizard.oC
Stack Trace:
javax.swing.plaf.basic.BasicFileChooserUI$AcceptAllFileFilter cannot be cast to roomeqwizard.oC
roomeqwizard.gB.A(y:73)
roomeqwizard.gB.F(y:3104)
roomeqwizard.gB.a(y:5044)
roomeqwizard.gB.O(y:480)
roomeqwizard.gB$20.actionPerformed(y:208)
javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
javax.swing.AbstractButton.doClick(AbstractButton.java:376)
javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:842)
javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:886)
java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
java.awt.Component.processMouseEvent(Component.java:6539)
javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
java.awt.Component.processEvent(Component.java:6304)
java.awt.Container.processEvent(Container.java:2239)
java.awt.Component.dispatchEventImpl(Component.java:4889)
java.awt.Container.dispatchEventImpl(Container.java:2297)
java.awt.Component.dispatchEvent(Component.java:4711)
java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
java.awt.LightweightDispatcher.processMouseEvent(Container.java:4535)
java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
java.awt.Container.dispatchEventImpl(Container.java:2283)
java.awt.Window.dispatchEventImpl(Window.java:2746)
java.awt.Component.dispatchEvent(Component.java:4711)
java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
java.awt.EventQueue.access$500(EventQueue.java:97)
java.awt.EventQueue$3.run(EventQueue.java:709)
java.awt.EventQueue$3.run(EventQueue.java:703)
java.security.AccessController.doPrivileged(Native Method)
java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
java.awt.EventQueue$4.run(EventQueue.java:733)
java.awt.EventQueue$4.run(EventQueue.java:731)
java.security.AccessController.doPrivileged(Native Method)
java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

The .cal calibration file cannot be loaded by REW, how can I evaluate the delay and remove it from the measurement? Could you give an example of the correct procedure?
Thanks John, with your explanations I learn a lot !!!

 

[Antonio Di Motta]

I attach the debug file

 

[John Mulcahy]

If you don't set the file dialog to "All files" you shouldn't see the bug, I have fixed it for the next build.

When REW makes a soundcard calibration it performs the Estimate IR delay process on the measurement and removes any delay it finds, otherwise the cal file would contain the phase shifts from any delays in the measurement path, which could vary. The check measurement you made was with no timing reference, so t=0 was at the IR peak. The IR peak is not the true t=0 position for the measurement, if you run Estimate IR delay on it you will see REW say that there is an estimated delay of -0.003 ms. If you go ahead and let REW remove that delay, you will see that the phase response with your cal file loaded is now perfectly flat.

If you want to make a cal file that includes some known delay that you are sure will be constant, you can make a measurement and save that measurement as a cal file. Before you do that you should adjust the SPL offset of the measurement so the measurement is zero at 1 kHz.

 

[Antonio Di Motta]

Thank you very much John, I do tests to make sure I understand the things you told me correctly.
Greetings, Antonio