OT: actual RS sound level meter accuracy data

R0cky wrote on 5/17/2005, 11:17 AM
Just tested my RS digital SPL meter with an Extech sound level calibrator.

The calibrator specs: 1 KHz +/- 5% 94 dB SPL +/- 0.8 dB

The results are all the same on A and C weighting, slow and fast response:

89 dB i.e. 5 dB too low out of the box. Could be worse by 0.8 dB given the calibrator tolerance.

The calibration adjustment had only enough range to bring it up to 91 dB.

Comments

PipelineAudio wrote on 5/17/2005, 4:04 PM
if you are feeding it sine waves, the weighting and response speed may not matter.
R0cky wrote on 5/18/2005, 7:35 AM
I just wanted to see if it was repeatable - for a 1 kHz sine wave it should give the same response for all combinations of weighting and response time.

New data on the quality of Radio Shack assembly (as if there was any doubt):

I took it apart to see if there was an internal cal adjust so I could get more range and actually adjust it to the cal value. There was not, but when I put it back together it started reading the cal value of 94 dB SPL (vs. 91 dB and no more adj. range prior to disassembly) and was able to be adjusted around that value. Perhaps I got the screen over the mic in the right place or something......

FYI: Extech (maker of the calibrator) has a SPL meter for $79 (digital) and an analog one for $59 at http://www.testequipmentdepot.com/extech/soundmeters/ - these are still quite cheap and I have to believe much better quality than RS.

We have one of their more expensive models at work that we use for noise level measurements. It consistently reads within a couple of tenths of a dB of the calibrator value. Accuracy spec'd at +/- 1.5 dB. The cheap ones above are spec'd at +/- 2.0 dB.