SPL meter odd behavior

Here's the type of adapter that I recommend you use right at the output of the ( Extech ) SLM .



From this adapter to the next set of adapters ( going into the computer ) you use a regular single male RCA to male RCA ( as an extension cable between computer & SLM ).



Going into the computer ( & assuming you are using the typical soundcard of a laptop ) you'll need something like this ;



Get the above adapters ( or something representing this very concept ) .

:sn:

ps ;
> You can not use a single cable like the following ( & get away with it ) to patch the SLM directly into the computer .
> All you'll do is short out the signal in the front end of the computers' soundcard and then you'll get goofy symptoms such as you are describing .

I found a set of RCA cables and adapters in my shelf and tried connecting the SLM the proper way but the input volume is much lower.



I'm not sure these cables were originally meant to deliver audio signal but that's what I could find.

Tried experimenting with lots of different adapters and cables but still haven't got anywhere.
It seems that the SLM 3.5mm mic out outputs signal using left channel and computer can pick up that signal only if SLM is connected to the left soundcard input (not right. weird?). the problem is that input volume is maxed out in silence and REW's SPL meter displays "over". Where is the problem? Is it in the SPM itself?

Click to expand...

> Your meter outputs a mono signal, on a mono type receptacle ( called a "jack" ) .

> So quit plugging into that jack a stereo plug with the ( erroneous ) assumption that you'll get the full available voltage outputting from the SLM ( we have no way of knowing if your approach will work apart from contacting the maker of the meter or actually making some comparitive AC voltage measurements ).

> In my second post ( first pic ) I displayed a link for the necessary adapter that you need to get to plug into your SLM ( it's a mono adapter ).
> An adapter like this will guarantee that you get full voltage outputting from meter to computer .

:foottap:

Anyways :

> This is all a really pointless excercise ( in signal routing ) since there's no generic soundcard calibration file available for your Extech meter / meaning ; without a meter calibration file you can't believe much of what you see on the computer screen,( assuming you figure out the signal routing for your Extech ) .

> I recommend that you buy a Radio Shack type SPL meter ( with mono RCA out ) that you can easily interface to a laptop using the other 2 adapters displayed within my second post .

:sn: