Measuring in-ears the budget way.

As you probably noticed on the end of my BGVP DMG review I shared some measurements of the frequency response of the nozzle filters.
As we speak I still have the doubt if I should share measurements done with amateur tools but then again because I’m an enthusiast I can’t really look the other way.
In the case of the DMG the nozzles are a good example of amateur measurements helping the hobby because I’m sure no professional outlet wouldn’t pick up a Chi-Fi model to measure it.

Right now I measure in-ears using a piece of transparent tube, a Dayton Audio iMM-6 calibrated microphone, a 1gen iPad mini given to me by my nephew and Andrew Smith FFT iOS app. The app is a must if you want to measure using the iMM-6.

Measuring Setup in-ears 2
Microphone setup for measuring in-ears.

Why an iPad? Well, as gear goes the iPad has a pretty solid A/D converter on the microphone line in.

Also, the app is probably one of the best ones around. I should know because I bought most of the ones you could buy for android.

Right now I measure in-ears at night after my kids go to sleep and the streets are silent, I also shut down any noise source like my desktop computer or house fans during the measurement session.

After setting up the iPad mini with the iMM-6, I check if the microphone calibration file is loaded and if it’s set to full range.
Then I connect the in-ear to the hose with a small “starline” tip that will be at around 3mm of the faceplate of the iMM-6.
I check if both hose and tip are sealed and calibrate the IEM sound output to +/- 95dB with pink noise (mono). If I fail to seal the tip the measure will lack bass, so I must measure twice to be sure everything is sealed correctly.
The FFT plot is set to 16384 points “hamming” with a 50% overlap and averaged for 30 seconds, it’s then 1/24 Octave smoothed so all the minor jagged edges are removed.
The FFT plot you see in the end is the raw data one.

Besides the fun of reading an FFT, it’s also a great tool to check for mismatched or defective gear. Any unbalance will be noticed when comparing plots.

I know that I should use white noise for the FFT but Andrew Smith recommends pink noise when doing measurements and he’s not the only one saying it.

My measurements are of no use for people outside my blog because they don’t adhere to a standard and are not peer-reviewed. I do wish some company would make a professional measuring tool that could be used by any enthusiast to compare in-ears in a repeatable way.

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