WHAT does a measurment mic do????

[bfoundation81]

i have heard of these and seen them but im kinda confused about them. What can they be used for or what the hell do they do exactly?????

 

[Dot]

Measurement microphones are used to measure decible levels of anything that makes noise, and are used in industrial and environmental applications such as car manufacturers, construction, demolition, factories, jet engine testing...

The industry leader in measurement microphones is a Danish company called Brüel & Kjær. You can find out a lot more info about these types of mics arnd their applications at http://www.bkhome.com/

 

[sdelsolray]

They're also used as a reference for testing other mics. That frequency graph you see for mic "X" is a comparison between that mic and a ruler-flat measurement mic.

 

[Darsu]

I've been wondering about this as well. If the frequency graph of these things is basically ruler-flat, then what's the functional difference between a Behringer and a Brüel & Kjær?

 

[baekgaard]

I've been wondering about this as well. If the frequency graph of these things is basically ruler-flat, then what's the functional difference between a Behringer and a Brüel & Kjær?

Good question. Some answers below:

The B&K mic is ruler-flat to a higher degree of flatness than the Behringers. The Behringers are probably having a +/-1dB tolerance in real life, and may change over time. Thus, two Behringer mics may have slightly different characteristics, and could potentially be off by maybe 2 dB when compared. (Note that 1dB is still quite good, but not for very critical use).

The Behringer mics are also much more noisy, and will not work in as wide a dynamic range as the B&K mics, that can (for some models) probably handle the sound pressure levels coming from a jet engine on 1m distance without distortion.

The B&K mics keep their sensitivity over a wide range of temperature, air pressure and humidity. The diaphragm does not deterioate in harsh environments. Once calibrated, they stay like that for a long time, and needs less frequent calibration. The Behringers need much more frequent calibration. The B&K mics can thus better be used for absolute measurements (i.e. determine the real Sound Pressure level).

The B&K mics also tend to distort very little, and does not add anything to the signal at all. The Behringers will distort much more (intermodulation). If you want to measure a loudspeaker frequency and impulse response, this is critical -- if the mic has a higher THD or IM, how can you say anything about the loudspeaker you're measuring?

The B&K mics will also have a very uniform circular polar pick-up pattern. The Behringer mics probably have a less uniform pattern.

The B&K mics are supported by a wide range of accessories, such as calibrators, that can help you keep them in top shape.

They are also manufactured with better material (e.g. nickel membranes versus electret material -- making a large difference in stability) and much smaller tolerances. And they are individually tested, verified and calibrated.

So, for critical and professional use, you need the B&K mics.

If you just want to find out how your room sounds and check the room modals, a Behringer mic is fine. Or if you want to do a rough setup of an 31-band EQ for live setup, they are also fine. Or if you want to check the response of a loudspeaker at home, where other factors are having a much larger influence than the measurement mic. Or if you simply don't want to risk that someone spoils your mic in a live setup.

I used to work with B&K, and had a short time also with the group that did the studio mics (now known as DPA).

I may be biased... but I actually have a pair of Behringers that are OK for my private use at home: Either as a "generic" omni SDC or as a "reference" for checking my monitors and room modals. But I would never consider using the Behringers for professional use. If you have millions invested in a really sound-dead room, you don't really want to save a few bucks on the most critical component in your measurement system, would you

Hope this helps?


-- Per.

 

[sdelsolray]

Mircotech Gefell also has a measurement mic set of products. Both B&K/DPA and Gefell have used some of their respective measurement mic technology in some of their respective studio mic products.

 

[boingoman]

Isn't it the equipment, rather than the mic, that is calibrated? I have a Klark Teknik analyzer, and it is calibrated for the mic it came with.

 

[baekgaard]

Isn't it the equipment, rather than the mic, that is calibrated? I have a Klark Teknik analyzer, and it is calibrated for the mic it came with.

Sorry about the confusion. If I read you correctly, you ask whether an adjustment is made to the microphone or to the analyzer when they together are calibrated.

In most, if not all, cases, the adjustement is made to the analyzer.

The confusion stems from the use of the word "calibrate".

To most people, it implies "to adjust" (definition 4 below). However, as a technical jargon, it often means "to determine deviation from a standard to find the correction factor" (definition 3 below). This deviation is then subsequently adjusted for manually or by entering a value into the analyzer/instrument -- which is then loosely said to be calibrated.

Some instruments can even do an auto calibration procedure, whereby a known stimulus is applied to the measurement probe (here: microphone), and a compensation is then applied until the correct reading is obtained.

Hence, when I said "calibrate the mic" I meant this later definition as a technical jargon -- as evidenced by Merriam-Websters definition 3:

From http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=calibrate&x=0&y=0:

Main Entry: cal·i·brate
Pronunciation: 'ka-l&-"brAt
Function: transitive verb

...

3 : to standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors

4 : to adjust precisely for a particular function

So, yes, in a sense you are right -- the mic is usually not adjusted; the instrument using the mic is adjusted. But the mic is sometimes said to be calibrated when its sensitivity has been determined and correction factors are known and can be applied in the instrument.

As mentioned previously here, I'm not native english, so I apologize if my use of english terms are somewhat unorthodox.

Hope this clears the confusion?


-- Per.

 

[boingoman]

As mentioned previously here, I'm not native english, so I apologize if my use of english terms are somewhat unorthodox.

Hope this clears the confusion?


-- Per.

Your English is excellent, and always clear.

If I tried to post in Danish, I would probably start a war, or be arrested for crimes against language.

 

[baekgaard]

Thanks!

Your English is excellent, and always clear.

Thanks, guys, for the kind words and the rep points


-- Per.