Measurements with Umik 1 & 2 always show (big) decline above 12khz

[satefan]

All;

I have been wondering about this for a while, but doing a measurement with my Umik-2 on someone else speakers brought this topic back to actuallity (is that a word?).

Since I have been using my Umik 1, and later the Unik 2, i have been seeing a decline in measurement response above 10K. Initially i figured this has to do with the tweeter I was measuring (SB acoustics), but when i upgraded to Bliesma tweeters later, i was still seeing the same. I was thinking that it could be that I am measuring with a Class D (Hypex) amp, which has a bit of decline as well I heard, but not sure about that.

Last Saturday I measured someone else's system (with my MIC, but on a different computer and a non class D amp), and witnessed the same. I did use the correct calibration file.

Below is a screenshot of the measurement (of the unfiltered SB Acoustics tweeter from a few years ago).

Is there something I am missing? Is this normal?

Thanks for all your help,

Satefan

 

[thothsong]

Are you measuring nearfield or at distance? 0 degree or 90 degree?

 

[satefan]

I am measuring from 1 meter distance on 0 degrees.

 

[thothsong]

Try a 0 degree nearfield measurement (at reduced volume).

 

[satefan]

Will do so. This will give me some insight if baffle-diffraction etc have something to do with this perhaps. The dropoff is at high frequency, so shorter wavelength. Let's see.

 

[DanDan]

Unless the Mic is precisely equidistant to both tweeters, HF cannot sum accurately. Measure L, R, and L+R

 

[Anatoliy Gavrilov]

I am measuring from 1 meter distance on 0 degrees.

Also check the high frequency in the settings of your sound card and computer.
When measuring the frequency response of 15 kHz, it passes through a level of -1 dB relative to a frequency of 10 kHz - this is quite normal for a tweeter with a fabric dome.

 

[satefan]

Unless the Mic is precisely equidistant to both tweeters, HF cannot sum accurately. Measure L, R, and L+R

Thanks for your comment. I am measuring one loudspeaker (the tweeter in this case) at a time. I use REW mostly for loudspeaker design.