Mic as Sound Level Meter?

Queue

Queue

Active member
So, my Rat Shack meter only goes down to ~50dBA. If I'm working on reducing the noise my PC makes, I'd like to be able to measure my progress.

Can I somehow calibrate my recording levels and use a microphone as a sound level meter?

Recording Rig:
Aardvark DP 24/96 preamp & A/D/A

Mics available:
SM57
ECM8000
SP C1

I'm not looking for EXACT measurements, just a way to measure my progress.

Queue
 
hey Queue, if you want to measure your progress then you can do a relative measurement.

I'll use the ECM 8000, as they are flat and omni. I'll connect one to directly to the card (does it have phantom power), and then I'll dial a gain and write it down, to use it on the subsequent measures. Then I'll record different situations and I'll look directly at the bits in your waveform editor, as this is the ultimate number that matters. In Protools, for example, there's a gain plugin that can search for peaks. If your measuring noise then you'll have everything else pretty quiet. That way, a peak could tell you some good info since the dynamics of constant noise shouldn't be so much. Also, when I ran my cursor thru the wave, it tells me the numerical value of the amplitude.

All this won't tell you absolute values, but it will surely tell you if you're improving and how much in bit terms, which is a pretty precise way of viewing it.

This is the end of my method, I'm sorry if it is too primitive but it's my best guess. I also wish that somebody has a clear idea and post on how to calibrate your DAW to a known measurement scale.

As you said you have a Radio Shack meter, you could trust it and calibrate your measurement plugin to it at 50dba. But I don't know if that's easy. Why don't you do it and watch them react to see if they follow one another?

Cheers, Andrés
 
Hey Andres,
Yes, I do have phantom power, and I figured the ECM8000 was the best choice for this task.

I have a tone generator program that I can probably use to aid in calibration.

Hopefully one of our more knowledgeable members will chime in and let me know if this is an exercise in futility or not.

I can't justify spending a couple hundred (or up to 1000) dollars on a meter.

Queue
 
yes Queue, that'll be great. Anybody knows how to convert your DAW into a metering machine? Harvey?
 
There is a great PC RTA software package that you can download and use called SpectraRTA from Sound Technology. Just make sure that the PC's record levels are always the same. A simple level meter is not as releaving as a good RTA. Face it, not all frequencies are objectionable to the same degree. The RTA can help you identify where the obnoxious noise are in the spectrum.

You may be able to quiet the noise considerably without actually lowering the C Weighted RMS SPL values by only tweaking out the offensive sound of the PC.
 
It is expensive I know that. Allen and Heath have a free one that is also very good. It is just called RTA and the version I downloaded was RTA122.
 
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