Originally Posted by metallicaband
I'm a bit confused about the whole calibrated mic stuff,
Mic calibration is not the most important thing if the mic has reasonably good frequency response.
IMO, Ethan did a real service to the audio community by posting this article comparing a lot of likely measurement microphones:
In that article he posts the following comparison of measruements of a real world system as performed using a number of likely mics:
He publishes other info, so you definitely need to read the article.
My summary of the above graph is that from 50 Hz to 10 KHz, which is the range where frequency response is most important, the mics gave results that are so close that as a practical matter, they are interchangeable. This is really pretty amazing for a bunch of more-or-less randomly chosen samples of mics that have such different prices and look so different on their spec sheets.
The background behind this is that about 30 years ago Panasonic started making 1/4" (6 mm) electret mic capsules that sold for $2 and had phenomenally flat frequency response. They have been cloned by many manufacturers, and the cheap measurement mics are basically $2 electret capsules with the makings of a pro mic wrapped around them. The trouble with electet mics is that they are internally charged with a static charge that tends to leak away, unless they are very very carefully made. Their output is proportional to this charge, so if it leaks away the mic becomes less sensitive but tends to keep its frequency response the same.
Even $2,000 lab measurement mics are electret mics under the skin, but they are made super-carefully using expensive materials and put together and checked very carefully by skilled technicans. The $2 ones are made out of cheap materials by a machine. However, cheap materials and machines can be pretty good.
Now you may know why I wince a bit when people start talking about expensive mics and calibrated mics.
On balance I know from practical experience that there are such things as defective mics and mics that become defective while sitting on the shelf. It has happened to me several times. The two most common failures that I have seen is that the mics either stop working entirely or become far less sensitive (IOW like a 10 dB loss) to sound. This will happen whether or not the mics start out being individually calibrated.
If you are a believer in calibration, then the logical approach is to recalibrate them before every use. I know people who do this and if you have the resources, its a good idea. BTW that's the big practical difference between a $50 measurement mic and a $500-1000 measurement mic. The more expensive mic is often far more durable and stable. However, all measurement mics under about $300 are very similar under the skin. If they last they are great but watch out for spontaneous shifts, particularly in sensitivity.
Mic calibrators cost about as much as 5-50 inexpensive microphones, so maybe there is some way to get around using one and still get reliable results.Mic calibrators generally just provide a stable sound source at a single frequency. They are somewhat based on the idea that sensitivity is a decent indicator of the health of a microphone.
To me the above situation makes a point being that if you have say $100-200 to invest, you might be better off getting two nominally identical mics than one calibrated mic, and compare them every time you use them. If are very similar and stay very similar, then they are probably both OK. If one becomes significantly different from the other, then either one or both have become defective. Buy a replacement and compare again and repeat until you again have two mics that are very much the same.
That is actually about what I paid for most of mine. But in these times that is indeed a competitive price.
I'll definitely just get a calibrated version though if that will save me a lot of headache.
It won't.Edited by arnyk - 11/9/12 at 5:39am