smoothing on rough graph? Dayton Audio imm-6 on REW with downloaded CAL file

[RemedyMusic]

Hi there! I'm Edz a musician and simple, humble, and small time reviewer from Philippines! I just came from ASR and they pointed me here for more REW related topics as I was told this is an official forum for REW.

Straight to the point, ASR guided me to download the cal file of my measurement rig the Dayton Audio imm-6. I use this rig for measuring IEMs for objectivity for my reviews. I was able to incorporate the cal .txt file but something changed the way my graph looks. The apparent change is a rough line compare to my earlier measurements which are rather smooth.

Blue was a previously taken measurement. Red is the new measurement taken just now, with a more rough line. Any thoughts how to make them smoother?

Advance gratitude and my apologies if I have not dived deeper and went straight to posting a thread.

RemedyMusic

 

[John Mulcahy]

I suspect the cal file may be the problem.

Your measurement without a cal file has Inverse C correction applied, that is only to be used when measuring with a C-weighted SPL meter as the microphone. You should turn it off.

 

[RemedyMusic]

I suspect the cal file may be the problem.

Your measurement without a cal file has Inverse C correction applied, that is only to be used when measuring with a C-weighted SPL meter as the microphone. You should turn it off.

Hi sir John!

oh i see... would you mind showing me how to turn off the inverse C correction?

And I would like to share here also my main concern.

It has been consistent that my graphs lack gain compared to iec711. I know that each rig is different but this dilemma is constant. Blue line is iec711 green is imm6. As you can see, starting at 1khz, my gains begin to be less. Is there something on your mind that maybe can fix this lack in gains sir?

best regards
RemedyMusic

 

[John Mulcahy]

You can find the inverse C setting in the Cal files preferences. For existing measurements you can change it using the Change cal... button on the measurement panel.

You could make you own cal file from those two responses using the trace arithmetic A/B function, though it would be best to use the |A|/|B| function of the 5.20.14 early access build to make sure you are doing a magnitude-only calculation. Export the result as text and then load that as a cal file. The difficulty will be that the details of the response above 1 kHz or so become very dependent on the fixture so you may be best either applying some smoothing to the result before export or even making some manual edits to the exported data to smooth out the high frequency behaviour.

 

[sam_adams]

@John Mulcahy, since the IMM-6 .cal file begins with the line below:

*1000Hz -38.0 20.00 -0.7 20.55 -0.5 21.11 -0.2 21.69 0.1 22.29 0.3

How would REW handle the import of the file given the below from the help?:

• Only lines which begin with a number are loaded, others are ignored

Additionally, the line below from the cal file help has us waiting in anticipation:

• Spaces before values are

 

[John Mulcahy]

The first line looks like a form of sensitivity indication, though can't be interpreted without additional information on the test level and volume control settings. It will be skipped on import anyway, don't see any issue there.