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Discussion Starter #1
Hi, I bought the Mini DSP UMIK-1 microphone and when comparing the SPL meter in REW to the classic radio shack SPL meter, the REW measurement is 5db hotter. I have the correct calibration file loaded for the microphone, could it be something else?

Thanks,

Sean.
 

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Discussion Starter #4
When you say “ REW measurement is 5 dB hotter,” are you referring to the left-side markings on a frequency response measurement graph, or that REW’s SPL meter reads hotter?

Regards,
Wayne
Sorry about that, REW's SPL meter reads hotter than the radio shack SPL meter
 

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A few things to keep in mind:


* Assuming the calibration file has a sensitivity line, it should deliver accurate SPL readings from REW’s meter. The Radio Shack meters are lower-end Type 3 devices that typically have a +/- 2 dB variance, if not more.

* That said, I’d have more confidence in a calibration from Cross Spectrum Labs than one from miniDSP.

* Make sure you’re comparing apples to apples. The Radio Shack meters have only A or C weighted options. The C-weighting we normally use rolls out the lows below ~40 Hz. If you’re using REW’s Z weighting, it’s unweighted, which translates to flat response with no low end roll out. Thus with a low frequency signal that has significant energy below 40 Hz, it will read hotter than the C-weighted RS meter.

Regards,
Wayne
 

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Discussion Starter #6
A few things to keep in mind:


* Assuming the calibration file has a sensitivity line, it should deliver accurate SPL readings from REW’s meter. The Radio Shack meters are lower-end Type 3 devices that typically have a +/- 2 dB variance, if not more.

* That said, I’d have more confidence in a calibration from Cross Spectrum Labs than one from miniDSP.

* Make sure you’re comparing apples to apples. The Radio Shack meters have only A or C weighted options. The C-weighting we normally use rolls out the lows below ~40 Hz. If you’re using REW’s Z weighting, it’s unweighted, which translates to flat response with no low end roll out. Thus with a low frequency signal that has significant energy below 40 Hz, it will read hotter than the C-weighted RS meter.

Regards,
Wayne
Thanks for the information Wayne,

I assume a calibration from Cross Spectrum Labs would require purchasing the UMIK-1 from them?

Sean.
 
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