SPL meter with built-in calibrator?

[ulrik]

Hi,

The PeakTech P5055 SPL Meter has some kind of "internal calibration system (1 kHz sine wave generator)". Its manual contains the instruction: "Carefully adjust the sensitivity adjuster (8) with screw driver, until the display read within '94,0 +/- 0,2' dB". Normally microphones are inserted inside an external calibrator, but in this case the 1 kHz generator is somehow integrated into the SPL meter itself.

I wonder where the generator might be placed? Is a 13mm condenser mic omnidirectional enough at 1 kHz, to be calibrated with an internal sound generator located behind the capsule?

Or is it more likely that the sine wave generator bypass the microphone capsule and only calibrates the electronics?

Do you expect a SPL meter calibrated this way to be more or less accurate, compared with a SPL class 2 dBC meter only calibrated in factory by manufacturer? (e.g. UNI-T UT352)

 

[sonitus mirus]

I just grabbed my Reed R8060 (IEC Type 2) and calibrated it with an R8090. Both devices cost over $200 each when I purchased them. Using dB(A) (Fast), a $3.99 USD app in the Apple store running on my older iPhone 7 Plus was holding its own when held next to my relatively expensive, calibrated meter at various volume levels while measuring SPL at my listening position.

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It seems it does not take much to make a relatively accurate SPL meter.