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Calibrate SPL meter with measurement mic?
Old 13th November 2009
  #1
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scoring4films's Avatar
 

Calibrate SPL meter with measurement mic?

Is there a way to calibrate an SPL meter with measurement mic? I have a new uncalibrated SPL meter but no access to a calibrated meter. I do have a measurement mic though. Any ideas/suggestions greatly appreciated.

thanks
Old 13th November 2009
  #2
Mastering
 

Quote:
Originally Posted by scoring4films View Post
Is there a way to calibrate an SPL meter with measurement mic? I have a new uncalibrated SPL meter but no access to a calibrated meter. I do have a measurement mic though. Any ideas/suggestions greatly appreciated.

thanks
You can do it, but not with extreme accuracy, and you have to know the gain of your preamp, the exact sensitivity of your measurement mike (not the generic sensitivity, but that of your particular serial number), and regardless, there's still several obstacles. Pink noise should be less sensitive to room issues than sine waves, but either way, the positional difference between the SPL meter and the mike.

Does your meter have a calibration trimmer? If so, I have a calibration generator. It's recently been checked so it's as accurate as you can get; but it is sensitive to barometric pressure variations so you can send it to me if you're near sea level as I am. But if you're on a mountain then send it to someone who has a more sophisticated calibrated generator that's not sensitive to barometric pressure issues.
Old 13th November 2009
  #3
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scoring4films's Avatar
 

Thanks Bob, I'm about 1100 ft. above sea level here, but I will keep your offer in mind for the day I buy some ocean front property
I suspect you wouldn't want to be caught dead with the SPL meter I'm trying to calibrate anyway. It's one of the new iPhone/iPod apps, several of which are labelled by the developer as "for entertainment purposes only" (although there were no such warnings on the one I picked up -- SPL Meter | Andrew Smith). For what it's worth, this meter does have a calibration trimmer. I did go to the trouble of getting one of the better external iPod mics (had the flattest response in 3rd party tests) in hopes that the app would let me check mixes at 85, give or take a couple of dB. I thought there might be some way to play pink noise into my measurement mic at a fixed/known level (in dBFS?) and then cross-reference it with the SPL meter, but from what I've read it ain't that simple (which is often the case, it seems)

thanks again...
Old 13th November 2009
  #4
Mastering
 

Quote:
Originally Posted by scoring4films View Post
Thanks Bob, I'm about 1100 ft. above sea level here, but I will keep your offer in mind for the day I buy some ocean front property
I suspect you wouldn't want to be caught dead with the SPL meter I'm trying to calibrate anyway. It's one of the new iPhone/iPod apps, several of which are labelled by the developer as "for entertainment purposes only" (although there were no such warnings on the one I picked up -- SPL Meter | Andrew Smith). For what it's worth, this meter does have a calibration trimmer. I did go to the trouble of getting one of the better external iPod mics (had the flattest response in 3rd party tests) in hopes that the app would let me check mixes at 85, give or take a couple of dB. I thought there might be some way to play pink noise into my measurement mic at a fixed/known level (in dBFS?) and then cross-reference it with the SPL meter, but from what I've read it ain't that simple (which is often the case, it seems)

thanks again...
Aha. I've seen that Iphone app, it's very cute! Makes maximum use of the hardware. My calibration unit would not work with the Iphone anyway, it has to have a standard cylindrical mike of one of three standard sizes. When you're in the vicinity of someone with a "reasonably calibrated" SPL meter, then put the Iphone up next to it and see how close they come. If you're within a dB after your cal you should be "good enough for government work".
Old 7th January 2010
  #5
Gear Maniac
 
Proggm's Avatar
 

Slightly off topic, you should try this one:
SoundMeter
Old 7th January 2010
  #6
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Harvey Gerst's Avatar
 

Verified Member
We need a simplified acoustic calibration standard that is repeatable; something like dropping an Alesis 3630 compressor from a 12 foot height onto a concrete surface and measuring the SPL produced at 1 meter. That would be consistent, repeatable, and a public service to the rest of the audio industry.
Old 17th February 2013
  #7
Here for the gear
 

resurrecting a dead thread :D
I agree 100% with you Harvey, we really need repeatable standard procedure for a known SPL reading at given frequency weighting used.. that would be very useful.
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