Creating a correction profile in REW from a known good mic for a second mic

[natty]

Maybe this is so simple, no one has described the steps before. In searching the forum I found references to the procedure but not description of the procedure. I'm hoping I missed it and someone can point me at it.

I've got a UMIK1 with a correction file form cross spectrum labs. I'll consider it my reference.

I've got a simple USB mic from a Paradigm room EQ system (Anthem Room Correction) that doesn't have a correction file. I want to create a correction file for it.

Once I've got a graph for each mic in REW, how do I generate that "difference" file, and how do I save it in a format that will let me import it into REW as a correction file for using the "new" mic later?

 

[natty]

Went through the documentation again. Can't seem to find the steps to do this. I'm guessing that means this is not a supported feature of REW yet. Would be great to see it added, since I have a UMIK with calibration files from Cross Spectrum, but also have two uncalibrated USB measurement mics from ANTHEM for use with their ARC implementation, and would love to profile things to create a correction file for them.

 

[Wayne A. Pflughaupt]

The only way I’m aware of is to take an in-room measurement with both mics, and make a calibration file for the mic in question based on the deviations from the reference mic.

Regards,
Wayne

 

[natty]

The only way I’m aware of is to take an in-room measurement with both mics, and make a calibration file for the mic in question based on the deviations from the reference mic.

Regards,
Wayne

That makes sense and seems straight forward.

Its the step after having the two measurements I am less clear on: How do I generate that "difference" curve and save that as a correction file?

 

[Wayne A. Pflughaupt]

Here’s an old post from Home Theater Shack that should be helpful.

EQSetup

I want to use the EQ wizard to check my room frequencies and I do this with just my radioshack meter and a condenser neuman microphone

www.hometheatershack.com

Regards,
Wayne

 

[natty]

Thanks for the link. Looks like the process is to manually note the deviations and create a text file. I hadn't even thought of that. I sort of assumed there must be a way to export the response delta graph and convert that to a correction file. I'll have to explore this further.

 

[forumuser]

I recently wanted to check my new Behringer ECM8000 against UMIK-1 as ECM8000 didn't come with a cal file. My objective was to see the difference, not to create a cal file. In a nutshell

- I duck taped two mics to the same mic stand. 0 degree (horizontal), the distance between mic tips was around 1cm
- Took a measurement in REW at MLP for each mic (total two measurements)
- Exported each measurement separately as a text file
- Imported text files into Numbers (Mac). Excel fine too. Three columns for each mic (Fr, dB, Phase)
- Subtract dB from each mic data for the same Freq (so, you don't need to do it manually). I did not use phase data to check.

If you want to get a more reliable data you can take several measurements for each mic and get an average dB in Excel (or similar) before doing the subtraction.

Hope this helps

 

[natty]

I recently wanted to check my new Behringer ECM8000 against UMIK-1 as ECM8000 didn't come with a cal file. My objective was to see the difference, not to create a cal file. In a nutshell

- I duck taped two mics to the same mic stand. 0 degree (horizontal), the distance between mic tips was around 1cm
- Took a measurement in REW at MLP for each mic (total two measurements)
- Exported each measurement separately as a text file
- Imported text files into Numbers (Mac). Excel fine too. Three columns for each mic (Fr, dB, Phase)
- Subtract dB from each mic data for the same Freq (so, you don't need to do it manually). I did not use phase data to check.

If you want to get a more reliable data you can take several measurements for each mic and get an average dB in Excel (or similar) before doing the subtraction.

Hope this helps

Thanks for this. Yes!

That is the same way I have been approaching the measurement part. I assume that as long at the mics are co located, the goal is the delta file in what they are measuring.

Then, creating the correction file form the delta.

Glad I am on the right track

-----

I'm still trying to learn the format of the text versus frd file, which one to use, and how to translate my delta data into the right format....because they are not quite as straightforward as I thought at first.

For example, I have them both from cross spectrum labs. Here is the text file for my mic (beginning below 11hz):

"Sens Factor =-0.908dB, SERNO: 7004060"
"Auto-generated 90-degree calibration file for use with nanoAVR DL"
10.054 -8.6543
10.179 -8.4640
10.306 -8.2768
10.434 -8.0930
10.564 -7.9122
10.696 -7.7345
10.829 -7.5600
10.964 -7.3885

Here is the FRD version, narrow band 90, (again just be beginning below 11 hz):

4.33 -10.16 0
5.79 -7.24 0
7.24 -4.78 0
8.69 -3.27 0
10.14 -2.3 0

These two formats are easy enough to understand and create from my delta file.......at first glance. But then, I look at the details, and I am missing something key. How could the text file version be correcting things about 10 hz at about 8db, but the FRD file is correcting things about 10hz about 2 db?