About 5 years ago I purchased one of those cheap ($20) sound pressure level meters (SPLM) on ebay.
As usual the unit itself wasn't quite as schmick as it looked like online, with the plastic case being a bit wonky but it worked fine and was within 2dB (between 50 to 100 dB) of a high end unit I checked with at work. below 50 dB it read =>3dB too low and I didn't check it above 100 dB
The cheap meter came with a preinstalled Chinese battery (one of those where you pull the clear plastic tag to make the connections) and I used it on and off for a few months and then as happens with these things it sat in a drawer for a couple of years.
Then I needed to do some measurements it did not switch on - check battery - dead - replace battery and it still didn't work.
I was not that upset about it given it was the cheapest unit at the time so I tossed it back into the drawer.
This morning was clean up time and stumbling across the SPLM I thought - I'll give it 15 minutes worth of my time and if no luck it gets chucked. 4 screws had it open and I immediately spotted that the marked power polarity on the circuit board did not match the markings on the battery compartment. Flipped the battery over and it fires up and works fine.
It's all a bit redundant because I since purchased a Faber Acoustical SPL iPhone App which is also good to within 2 dB of the unit at work. There are of course plenty of free mobile SPL apps which even though they might not be absolutely accurate, are generally good enough for comparative measurements.
As usual the unit itself wasn't quite as schmick as it looked like online, with the plastic case being a bit wonky but it worked fine and was within 2dB (between 50 to 100 dB) of a high end unit I checked with at work. below 50 dB it read =>3dB too low and I didn't check it above 100 dB
The cheap meter came with a preinstalled Chinese battery (one of those where you pull the clear plastic tag to make the connections) and I used it on and off for a few months and then as happens with these things it sat in a drawer for a couple of years.
Then I needed to do some measurements it did not switch on - check battery - dead - replace battery and it still didn't work.
I was not that upset about it given it was the cheapest unit at the time so I tossed it back into the drawer.
This morning was clean up time and stumbling across the SPLM I thought - I'll give it 15 minutes worth of my time and if no luck it gets chucked. 4 screws had it open and I immediately spotted that the marked power polarity on the circuit board did not match the markings on the battery compartment. Flipped the battery over and it fires up and works fine.
It's all a bit redundant because I since purchased a Faber Acoustical SPL iPhone App which is also good to within 2 dB of the unit at work. There are of course plenty of free mobile SPL apps which even though they might not be absolutely accurate, are generally good enough for comparative measurements.
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