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Earthworks M30 microphone


Craig Leerman:

The M30 is one in a newer series of high-definition measurement microphones from Earthworks. It's specifically designed for field measurement of audio systems, with a near–perfect omnidirectional polar pattern, extended frequency response and fast impulse response, coupled with a rugged housing. The unit meets or exceeds American National Standards Institute (ANSI) Type 1 and applicable IEC 61094 requirements that deal with performance and accuracy tolerances of sound level measurement equipment.

Each M30 is provided with its own specific calibration chart showing the sensitivity and frequency response curve. A digital file containing the frequency response data is available from Earthworks for those who need to import it into measurement software. The mic ships in a foam-lined storage box that also holds a mic clip and calibrator adapter.

Let’s take a look at the specs. Frequency response is 5 Hz to 30 kHz (+/-3 dB), sensitivity is listed as 30mV/Pa (typical) and maximum SPL is 142 dB. The M30 is 9 inches long and measures .86 of an inch at the body/XLR end (.27 of an inch) at the capsule end, with weight at half of a pound. It needs phantom power to operate, and the user’s manual states that plugging in the mic “hot” (phantom power already present at the input) will not damage it -- and is actually preferred for faster settling.

Taking it of the storage box, the first thing I noticed was that the mic is quite solid and durable in feel. I plugged it into a test rig on the bench and listened over a loudspeaker to verify it was working. It sounded great as a live mic, so I decided to use it to check out the recording features on the Yamaha QL5 digital console also in for Road Test. While designed for measurement, it turns out that the M30 makes a pretty great recording mic, with very low self-noise and minimal handling noise.
Variety Of Tests
Satisfied the mic was working correctly, I connected it to my measurement rig that consists of a laptop with a Focusrite Scarlett 8i6 I/O unit. As I stared at the screen wondering why I had no audio, scratching my head, I decided the best course of action was to turn on the phantom power on the 8i6. One small button push later the rig came to life and I had audio to look at.

I used the M30 in a lot of applications. The first was testing out new loudspeakers at the shop, making sure they were all performing up to factory specs. I set up the loudspeakers in an arc and at equal distance from the mic, which was mounted on a short stand and pointed toward the ceiling. I could then mute and unmute the loudspeakers and compare the results. They all checked out, and so did the M30.

I also wanted to compare the new loudspeakers to another system already in the inventory so I set up stacks of both outside the shop. Placing the M30 at varying distances directly in front of each loudspeaker allowed me to see what they were doing, individually. Because the mic can handle up to 142 dB, I had no worries about damaging it with high-volume testing.

Next, a colleague who has finished building a small studio here in Las Vegas wanted to see what the room looked like on his measurement software. Seeking a second opinion on the M30, I lent him the mic for a week. To say he liked it would be an understatement -- he didn't want to give it back!

Built To Take It
I don’t always have the luxury of tuning a system with an empty room, with house staff, catering and other vendors setting up at the same time. At these gigs, I'm constantly worried that someone will carelessly knock over and step on the measurement mic while I'm at the laptop. But the M30 seems so rugged I firmly believe it could handle this type of abuse.

However, for obvious and understandable reasons, I didn't want to actually test this premise. Suffice to say that the M30 is the most durably built measurement mic I've run across in 30-plus years of doing sound.

Earthworks offers other mics in the series that I'm confident will work equally well, including the M23 (9 Hz – 23 kHz), the M50 (3 Hz-50 kHz), and the M30BX that offers a frequency response of 9 Hz to 30 kHz and has its own battery, thus no phantom power is required.

So if you're in the market for a field-ready measurement mic with a low noise floor, extended frequency response, and fast impulse response, the Earthworks M30 should be at the top of your list.

U.S. MSRP: M30 -- $999 (U.S. MAP: $679)

Lee Buckalew:

--- Quote from: Craig Leerman on January 18, 2015, 10:18:21 PM ---

The M30 is one in a newer series of high-definition measurement microphones from Earthworks.

--- End quote ---

Nicely written up review.  The M30 is a great measurement mic as are it's siblings in the line.

I would like to point out so that no one thinks this is a new product that the M30 Has been around for quite some time.  I am not sure how long ago it was introduced but I purchased my first one to go along with SpectraFoo when I was a beta tester during the development of the OSX version of Foo.  That should have been around 2001.



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