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Author Topic: Measurement Microphones  (Read 86727 times)

Iain_Macdonald

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Re: Measurement Microphones
« Reply #30 on: December 18, 2008, 04:48:21 pm »

Hi,

Just in case some of you might have missed it. Earthworks have a M23. This appears to have a much better price than the M30.

Iain.
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Tom Young

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Re: Measurement Microphones
« Reply #31 on: December 18, 2008, 05:22:55 pm »

I failed to mention Josephson as one of the leaders in high-quality measurement mic's. They make some very good mic's.

But I am not aware that they are considered to surpass Bruel and Kjaer, who have earned (as far as I'm concerned) their reputation, with many of their acoustic test equipment devices, as the leader.
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Tom Young
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HarryBrillJr.

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Re: Measurement Microphones
« Reply #32 on: December 18, 2008, 09:34:05 pm »

The M23 is similar to the Smaart M30 which was an OEM version for SIA.  Rational Acoustics carries something similar, perhaps it's the M23, I don't recall.
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Harry Brill Jr.
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Mac Kerr

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Re: Measurement Microphones
« Reply #33 on: December 22, 2008, 02:28:45 pm »

Mac Kerr wrote on Wed, 17 December 2008 11:55

I just took the opportunity to check my rather old, well traveled TC30k against a fairly new well cared for M30, and an Audix T40. This was done at about 8' from an L'Acoustics 108. Relative to the M30 my mic had a falling response starting at about 1k that put it down about 2dB at 20k. All the little system response dips tracked perfectly between the two mics. The Audix had a rising response relative to the M30 that put it about 4dB high at 20k, with a sharp rise above about 8k. When I can, I will send my mic in for service, but I am still fairly confident in its performance. I pack it in a plastic tube with foam ends, then in my tool bag, which goes in my suitcase, which goes in the belly of the plane many times a year. So far so good.

Mac

Here is a screen shot of the 3 traces. The magenta trace is the well cared for M30, the green trace is the Audix TR40, and the dark blue trace is my well traveled TC30k. Considering the time my mic has spent in airline baggage transport or in the trunk of my car, I am pleased with its performance. When I get a chance it will go back to Earthworks for a tuneup.

This is the untouched output of an L'Acoustics 108P. The delay shown in the screen shot is irrelevant it is not from the traces I saved.

Mac

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Jeff Babcock

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Re: Measurement Microphones
« Reply #34 on: December 22, 2008, 02:48:54 pm »

Yikes, the TR40 is around 6db hotter in the 5-7K range.  I'm surprised the difference is that significant.  Makes me really think twice about trusting a single mic, perhaps I should own a couple different ones and compare their results for more critical measurement applications.

Adam Robinson

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Re: Measurement Microphones
« Reply #35 on: December 22, 2008, 02:53:39 pm »

I own a TR40 and when I tested it against others, I did not have the same result.

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Art Welter

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Re: Measurement Microphones
« Reply #36 on: December 22, 2008, 03:08:31 pm »

Jeff,

Look again, the deviation is more like 2 or 3dB up high, the blue trace is down in level throughout the graph.

Not that 3 dB, a doubling of power is insignificant..

The problem is which mic is correct, the magenta and blue trace are more similar in the HF, so the green may be the one that is too “hot” on top.
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Art Welter

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Re: Measurement Microphones
« Reply #37 on: December 22, 2008, 03:11:21 pm »

Adam,

The different results you got are why individual tests are so important against a known benchmark.

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Mac Kerr

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Matching Microphones, or not...
« Reply #38 on: December 22, 2008, 03:19:09 pm »

Adam Robinson wrote on Mon, 22 December 2008 14:53

I own a TR40 and when I tested it against others, I did not have the same result.


Against what others? All mics will vary slightly, even 2 brand new mics of the same type. I did this test because I found that with 3 different speaker systems, dv-DOSC mains, VRX932 delays, and 108P front fills I was making very similar eq changes. I asked for the other mics to check to see if there was an issue with my measurement mic. While it is down in level it is not grossly different from the other Earthworks, so I remain fairly confident in its output. As I said, I will still get it checked at the factory, but I don't feel the differences in the 2 mics greatly effected the alignment of my system. Final tweaking was done by walking and listening to the transitions between zones and the overall coverage of the room.

Mac
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Jeff Babcock

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Re: Measurement Microphones
« Reply #39 on: December 22, 2008, 03:41:12 pm »

I realize the Audix is generally hotter in the traces which accounts for some of the difference - numbers aside there is enough difference in the Audix response vs the other mics that it would likely influence me, that's all I am saying.  Obviously ears should be the final judge but that might lead me astray.

ProSoundWeb Community

Re: Measurement Microphones
« Reply #39 on: December 22, 2008, 03:41:12 pm »


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