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TOPIC: Umik-1 Absolute SPL Error

Umik-1 Absolute SPL Error 4 years 5 months ago #19362

  • Carneoleon
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Hi all,

I have been using my umik-1 to measure both frequency response and sensitivity, using REW with the calibration file loaded.
Unfortunately my speakers measured a lot less sensitive than promised or simulated.
After some discussions on the DIYaudio forum we couldn't really find a problem in the method used for the measurements.
So I asked a colleague (i work at the audiologic center of the ENT department) to compare the umik-1 to their SPL meter. A RION NA-28, class 1 SPL meter, using the same settings on the REW spl meter.

scantekinc.com/products/sound-level-mete...8-real-time-analyzer

And with several types of noise we measured about 4dB less. (but this kept changing)
With something he called a 1kHz warble (continuously sweeping from 900Hz to 1100Hz and back) we got exactly 4,3dB less with the UMIK-1.
Slightly moving either spl meter didn't make a difference.
attached is a picture of how we set-up the spl meters and the speaker. The room is soundproofed.

My questions are:
- can i conclude that it is off-spec based on these measurements and observations
- if not, how should i do further tests
- is this covered in warranty?
- is this method used acurate enough to be able to add 4,3dB to the data or change the calibration file and subtract 4,3dB.

Thanks in advance :)
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Last Edit: 4 years 5 months ago by Carneoleon.
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Umik-1 Absolute SPL Error 4 years 3 months ago #20232

  • Carneoleon
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No takers?

Last week we dit another test, this time with my subwoofer. We used the same SPL meter as previous measurement, on a large open parking lot, on the ground, at 1,2M.
At both 60Hz and 50Hz. We got 3,6 and 3,7 dB difference, respectively. At a level of about 95dB(Z).

Once again, same settings on both devices.

Any input or thoughts would be very welcome!
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Umik-1 Absolute SPL Error 4 years 3 months ago #20249

  • devteam
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@ Carneoleon,

Sorry for missing your earlier post! It happens knowing we do get a lot of forum posts daily.. Do remember to use our tech support ticket system (Support - > Contact us) if you have immediate questions. Few comments for reference.
- The setup for calibration file is being done with a 94dBSPL @ 1kHz. The lower frequency is I guess a bit harder.
- Which setup are you using on the SPL meter? (i.e. compared to your REW setup) Peak vs RMS
- Using the calibration file, you can indeed easily edit the SENS factor (i.e.substract), it's a simple tweak from a text editor. .

DevTeam
MiniDSP, building a DIY DSP community one board at a time.
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Umik-1 Absolute SPL Error 2 years 6 months ago #31361

  • Carneoleon
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Thread revival!!

So, I've been using the umik-1 for some time now, adding 3,7dB to every measurement. And I got the SPL's I was expecting from every design I tested so far :)

However, a month ago I bought myself a new laptop(windows 10), installed the latest version of REW, and to my supprise I got way too high results! So with everything the same, I measured about 6dB difference between my old and my new laptop!!! I played with the settings a bit, nothing changed. I checked the calibration files, no difference. I'm not sure what's going on here :(
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Umik-1 Absolute SPL Error 2 years 6 months ago #31367

  • DorinD
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Hi,
did you use exactly the same levels for recording mic in

both laptops? Please check in Control_Panel>Sounds...
Regards,
Dorin

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