# Radio Shack SPL meter broken?



## hybris (Jan 25, 2009)

my radioshack spl meter (analog) has suddenly started acting weird. When nothing is connected to it it measures correctly, but when I attach the output to the mic on my laptop (I've tried two different laptops), the meter maxes out, seems like it's getting some kind of feed through the cable that makes the meter go bananas.. 

Anyone ever experienced this or has any idea what might I have happened? 

Thanks


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## brucek (Apr 11, 2006)

> the meter maxes out, seems like it's getting some kind of feed through the cable that makes the meter go bananas..


Since it's a laptop, I suspect you're using the mic-in port (which is not suitable for REW measurements), or a mic/line-in port.

Most computer mic-in ports supply a small DC voltage to operate the cheap computer mics that are available.

You usually require an external USB soundcard for REW when using a laptop.

brucek


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## hybris (Jan 25, 2009)

brucek said:


> Since it's a laptop, I suspect you're using the mic-in port (which is not suitable for REW measurements), or a mic/line-in port.
> 
> Most computer mic-in ports supply a small DC voltage to operate the cheap computer mics that are available.
> 
> ...


Haha - you're the best! That makes sense, the last time I used the meter I used an external USB soundcard. But I found a setting on my laptop where I could choose wether the mic input should act as a mic or line in. When I choose line in the problem goes away! 

Thanks a bunch!


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## wadesi (Jan 22, 2009)

hybris,
What model is your internal sound card? Other peopel that may have it or a similar model could look for the line in/Mic option...


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## laser188139 (Sep 19, 2009)

Not hybris but,
After using my wife's desktop system to take REW measures, I was pleasantly surprised to find that the soundcard on my laptop can be configured as LineIn as well as mic. It's a Dell XPS with a SigmaTel High Definition Audio chip. When I plug a stereo mini plug into the mic input, Windows Vista prompts with a dialog asking what kind of device is attached, offering a choice of mic, line in, or rear speakers. (The laptop has three audio jacks, two headphone/speaker jacks that can double as the front L/R and center/sub speakers, and a mic jack that doubles as the rear L/R speakers.)

The laptop soundcard is not quite as flat as the desktop system at the low end nor at the high end, but it using it for calibration I see similar results from both systems.


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## hybris (Jan 25, 2009)

I forgot to reply to this, sorry. 

The laptop that had the feature I described was a Dell XPS M1210 with a sigmatel sound card, probably the same soundcard that laser have in his. 

I also have a newer Dell Studio 15, this laptop do not have this option.


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