Preparing Calibration Files for minDSP UMIK-1

[rex.b...@dcineco.com]

If hand-editing the calibration files as downloaded from the miniDSP UMIK-1 web page is not to your taste, you may like this tool. It is an Excel spreadsheet that loads the published file and creates a standard format 1/3rd octave AudioTool calibration file. The tool shows plots of the mic response, the calibration curve and the theoretical corrected result. It also has the ability to use optional trim values where some particular corrected response is required.

To use it, download it to an appropriate folder and open it. You will need to allow macros. Click the Load UMIK-1 File button, navigate to where you saved the downloaded UMIK-1 file(s), select the required file and click OK. Wait a few seconds for the file to be loaded and the response to be displayed. Make trim adjustments if required (normally not). Click the Make CAL File button. The file UMIK-1.cal will be saved in the same folder as the tool. If you transfer the file to your tablet/phone, it can be loaded by selecting Load Cal on AudioTool's menu.

Whilst this will correct the frequency response for the UMIK-1 it does not calibrate the indicated SPL. This should be adjusted using AudioTool's Set Cal. Offset with reference to a mic calibration source. I found that my UMIK-1 needed an offset of +2dB to give the correct reading with a 94dB SPL1kHz source.

I have attached an example UMIK-1 calibration file and the resulting AudioTool cal file.  

[rex.b...@dcineco.com]

Although I had calibrated my UMIK-1 for response and SPL, I found that it read about 5 dB low when compared to other instruments. I rechecked the SPL calibration using a mic (sound pressure) calibrator and discovered a problem: The UMIK-1's head is only 12mm diameter so it doesn't seal properly in a 1/2" calibrator cavity. The quick fix is to replace the O-ring (mine was ID: 13mm, OD: 17mm, Thickness: 2mm) with a smaller one (ID: 12m, OD: 16mm, Thickness: 2mm). I also fitted a second O-ring to the mic head and pressed it against the outside of the cavity to ensure a good seal. The new reading showed that I needed a Cal. Offset of +7dB - exactly 5dB more than previously and accounting for the observed error.

So beware if you are calibrating a UMIK-1. It may not fit your normal mic calibrator properly!

If you don't have access to an SPL calibrator, there's a good chance that an AudioTool Cal. Offfset of +7dB would be close for most UMIK-1s on most phones.

 

[rex.b...@dcineco.com]

AudioTool Calibrate 2.0.0 can now load miniDSP UMIK-1 calibration files so this tool is now obsolete.

[Cristian P]

Thank you, used this today. 
AudioTool does NOT  load the miniDSP UMIK-1 file! 

[tsuki]

Did you end up getting AudioTool calibrated to the UMIK-1? Has anyone been successful calibrating AudioTool to the UMIK-1?

[Julian Bunn]

Can you send me the UMIK-1 file you are trying to load, and I will take a look?

[tsuki]

Nevermind, I found a conversation that answered the question I had.