Calibration Microphone

[alin_im]

Umik's have individual cal files for each mic. The 90 degree file is a calculated file based upon the size of the capsule and other factors. So that correction curve is the same for all of their microphones. They adjust the 0 degree file by combining those values with the 90 degree difference values. Since the Dayton looks nearly identical and uses a 6 mm capsule just like the Umik, the off axis change should be the same or nearly so.

I took the Umik 90 degree file (which I have for my Umik) subtracted 0 and 90 degree responses to obtain the difference. I then applied the same level of correction to the Dayton cal file. There is no correction until nearly 1500 hz and very little until 2500 hz and higher. I did some averaging, rounding etc to fit the Umik file to the Dayton file as the Umik has more data points. The Umik goes out to 3 decimal places while Dayton's is only one decimal place. So it should be about right, certainly in the right direction and approximate amount of correction.

Understood, sounds logical.

I will try what MAB said as well and maybe the guys at Spectrum Labs will send me some calibration files from other Mics, but at this moment I will just use what you produced.

So the idea is to measure 0 degrees for speakers etc and 90 degrees for room, correct?

 

[alin_im]

Hi all, coming back with some results from the calibration files of the Dayton Mic.

Using MAB methodology, I have tried the 90 degrees calibration file from Blumlein 88. I am not sure, but the formula to calculate the 90 calib file might have been a substraction instead of an addition. Please correct me if I am wrong, but I have reveresed the formula, and now the 90 degree response (with my 90 degree calib file) is the same as the 0 degrees response (with the original 0 degree calib file).

Attached you have all 3 calibration files and REW file.

Please let me know if the reversed formula is correct.

Red & Orange - 0 degree with 0 degree calibration file
Green & Yellow - 90 degree with 0 degree calibration file
Blue & Mint green - 90 degree with 90 degree calibration file from Blumlein 88
Purple & Light Blue - 90 degree with 90 degree calibration file from Blumlein 88 with reversed formula

 

[ACS_acoustics]

Just as a suggestion: (maybe for other future measurement situations)

This mic also has a rather lineair response. Not expensive: http://www.lineaudio.se/OM1.html
I can confirm that they are insanely matched / identical. In level and in frequency response. They not only measure but also sound great as omni.

If you already have an audio interface.... I would definitively go for a XLR mic. If you don't, then the benefit of USB is larger. If you choose for USB there is also a level calibration, that is nice. Level calibration is a 'thing' with just an XLR mic. Then you need extra stuff...

But if you have an audio interface... you could do measurements with multiple microphones. The program REW that most people use, now has the option for multiple mic's at the same time. Works really well. And with multiple input/outputs phase measurements are possible... that you just cannot do with just one usb mic. Meaning... you can go further... then 1x usb.

Another cheap microphone I found was the Mic W215, with some nice specs. I tried to purchase some, but there were some delivery issues... never got them. Now I don't need them any more.

I compared a few. I would personally stay away from the behringer mic.... The ones I saw... were too far of the other microphones.
If you've got the money... just go for earthworks. But that is a different price range