Um, I'm in about the same place you are, though I can't even find a mic that measures sensitivity with both of those units of measurement. I find things like:
Sensitivity (typical, at 1000 Hz; 1Pa = 94 dB SPL)
-37 dBV/Pa
Which is a bit more daunting as far as units and numbers go.
Now, knowing that these units aren't equivalent to the units on the mic you found, how do you compare the two? Are you ha ha ing too soon? Further, how do know that you're not cutting your own throat by purchasing a mic that's too sensitive for your application? (Not trying to be a smart ass, just looking to expand on this subject so I can learn a bit too)
Could someone out there convert these units to make them comparable, or are we on the wrong track here? I tried to look up a conversion but couldn't find an exact fit for all the units.
BTW, those figures are from a Shure KSM27, which judging by name and price alone
should be an awesome mic.
it's not really about conversion. and the ksm27 is decent, but not anything special. you can get more mic for less money. hang around for awhile and search the boards. you'll see.
mV/Pa simply tells you how strong a voltage signal is going to be sent out of the microphone at a 1 pascal sound pressure wave coming into the capsule.
pascals are simply units of pressure measurement. sound waves cause changes in air pressure--if you crank a woofer and put your hand in front of it, you can feel the air moving. so if you generate 1 pascal of pressure (which is, typically, a speaking voice @ 1" which will normally translate to -94 dB SPL, and -60 dBV--this " dB translation" issue is another animal entirely), that pressure is transduced from the capsule, through the mic electronics, into a voltage signal. this voltage is what travels through your cable, into your preamp, and is eventually digitally encoded back into sound.
a higher voltage ouput will require less gain from your preamp, because there's "more" audio signal being produced from the mic itself (higher amplitude). this is also called "sensitivity" although the term is somewhat misleading.
in general, condensers will always have a higher mV/Pa rating than dynamics, and ribbons will normally be the lowest of all. this doesn't necessarily mean that the SPL rating of a condenser will be lower than a dynamic (and ribbons can have quite low SPL ratings despite low mV/Pa ratings), so that's why you shouldn't put too much stock in this particular rating. if anything, a higher mV/pa rating is a good thing (as long as it's coupled with low self-noise) as long as the SPL rating is suited for your application.
so frequency response and SPL should determine whether the mic is suited for a particular application, speaking in dB. but remember that the SPL rating is always going to be at 1 kHz, so proximity effect can become a factor. usually if you're dealing with a mic that's rated for 140 dB SPL it can pretty much be used on anything, at any distance without overloading.
these ratings, as well as frequency response charts, are intended as a reference point, and really don't tell you much about the overall behavior of the mic. but it does give you a reference point. just don't make more of it than it is.
the best thing to do is to try to demo the mic in the application for which you intend it, but if this isn't possible, that's why this website exists. if you're looking for drum OHs, a vocal mic, etc, just use the search function to find the countless threads that are here to determine your best option. after that, if you have something that's more specific than the searches answer, ask that.
hopefully this has served to demystify better than it looks to me.
have fun out there!
