I have a Radio Shack SPL Meter, circa 1985. I had it mounted on a microphone stand with velcro.  I went upstairs this evening and found it lying in the corner of the space. The RS SPL had come undone from the attachment.
I am religious when it comes to listening volume.  Eighty percent of the time I listen@75 db or below.  Seven % of the time I listen@88 db and below.  Three percent of the time I listen@90 db.
The SPL Meter will not zero out.  The VU meter wavers at -6 db.  Should I trust my meter anymore?  Do you recommend I find a replacement? 
I need this thing to be accurate in a bad way.
 
the blind horse

Have an iPhone or an Android device?
Try an app called Decibel 10th by SkyPaw

I wonder how accurate those smartphone apps really are. They look cool, and you'll always have it with you. But I won't be convinced of their accuracy until I've tested one alongside a proper calibrated meter. The microphones in smartphones are dreadful, and I'm sure no measures are taken to assure consistency from unit to unit during manufacture, much less any kind of calibration.
 
blindhorse, I have an old ratshack meter hanging on the wall here, too. One of the best buys I've ever made. But I rarely use it. That's because once I know the relationship between the volume knob on my interface and the SPL levels out of the speakers, there's no need to re-measure. 
 
Because it's possible the microphone was damaged, it's unlikely you'll be able to repair it. I'd suggest replacing it if you can still find one. If not, maybe you can borrow one, take your measurements and mark the 75, 88, and 90 dB positions on your interface or Big Knob or the back of the speaker or however you adjust volume.

Thanks for the replies fellas,
 
gustabo, I don't have a phone that would download that app.  I'm still using an old Motorola with a 1" screen.  It does everything I need it to do though, I can even send texts. 
 
Bit, thanks for the advice.  I will try to find one on the cheap, and then try to learn knob positions.  I think I was getting close to knowing the levels coming from the monitors, and it was partly because I was judicious about constantly checking.
 
Thanks again, you guys are great.
the blind horse
 
 

blindhorse
I'm still using an old Motorola with a 1" screen.  It does everything I need it to do though,

Like....  acting as an SPL meter?    

Came across this link:
 
http://www.safetyawakenings.com/safety-app-of-the-week-42/
 
The article presents test results for a number of iPad/iPhone dB meter apps.  One was rated quite high for accuracy - although bitflipper is right to be skeptical about the consistency of microphones in multiple devices.  It could be that the iPad they used for these tests just happened to be right on the money.
 
Most of the apps were rejected as total junk.  One clear winner emerged: SPLnFFT Noise Meter.  Went ahead and bought it - couldn't resist at just four bucks.

 

karyn, you da man! 
 
dmbaer, as you relate, bit is right to express skepticism.  With that in mind, there are certainly technologies that transfer well.
 
We all do what we can. Varied information is a good thing; the wide muddy it may very well be.
 
We take hearing for granted, and often listen only when it matters little.
 
the blind horse

dmbaer
Came across this link:
 
http://www.safetyawakenings.com/safety-app-of-the-week-42/
 
The article presents test results for a number of iPad/iPhone dB meter apps.  One was rated quite high for accuracy - although bitflipper is right to be skeptical about the consistency of microphones in multiple devices.  It could be that the iPad they used for these tests just happened to be right on the money.
 
Most of the apps were rejected as total junk.  One clear winner emerged: SPLnFFT Noise Meter.  Went ahead and bought it - couldn't resist at just four bucks.

Thanks for the link, just bought SPLnFFT Noise Meter

Thanks for the tip, I just picked it up for four bucks as well.

I was going to do a test myself, comparing my Android phone and tablet to the Radio Shack meter. I went to the Play store and was going to download the free version of the highest-rated one. Right there in the vendor's description was a lengthy caveat about the limitations of such devices. 
 
He noted that the circuitry is optimized for speech frequencies and conversational levels, so don't expect any low-frequency response below 300Hz. You can see the obvious problem already: frequencies below 300 Hz represent 99% of the sound energy. Note that in the tests dmbaer linked to above, the test frequencies are 1 KHz and 8 KHz.
 
He also gives maximum SPLs for some different devices, ranging from as low as 80 dB (Samsung Galaxy S3, which happens to be my phone) to 100 dB (for the Moto Droid). My tablet maxes out at 91 dB. Makes sense; there is going to be a built-in limiter in there. That means the accuracy likely falls off the louder you get.
 
I think these apps would suffice for their intended purpose, which is not studio calibration duties but rather environmental testing. If you think you've got grounds for an OSHA complaint at your workplace, one of these apps would probably give you ammunition. Just don't expect OSHA to show up with an iPhone.