Cross-Spectrum Microphone Calibration Service - USA - Page 26 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #251 of 368 Old 02-19-13, 03:29 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

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Jargon wrote: View Post

What about their reliability and accuracy? Does anyone know about those three and how accurate they are?
With respect to reputation I would probably rank them 1) Cirrus; 2) Galaxy, and 3) iSEM, but I suspect any of the three will be adequate.
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post #252 of 368 Old 02-19-13, 04:39 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

I thought so. The iSEM is officially being carried by on the online store of the SMAART developers making me think they have at least tested it as well as their microphones that they also sell.

The thing with the Galaxy is reports from other users of the Earthworks M30 not fitting 100% (loose) but that was a post back from 2008. My M30 came with a 1/2" adapter so maybe it is perfectly fine.

In the end I will flip coins I think! Lol. Nonetheless, for what I want it as long as the iSEM is not totally out of specs and instead of +-0.5db variance it has +-3db then it seems to be the best deal out of the three price wise.
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post #253 of 368 Old 02-22-13, 08:11 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

Herb does the UMM-6 USB mic have the sensitivity factor available?
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post #254 of 368 Old 02-22-13, 09:43 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

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Herb does the UMM-6 USB mic have the sensitivity factor available?
No, the factory Dayton file doesn't give a sensitivity value and I don't trust measuring it simply because I don't know what settings constitute zero gain.
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post #255 of 368 Old 02-24-13, 03:12 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

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No, the factory Dayton file doesn't give a sensitivity value
I think it is in the first line of the Dayton cal files, e.g.

"Sens Factor =-23.555dB, SERNO: 1280303"

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and I don't trust measuring it simply because I don't know what settings constitute zero gain.
For these USB mics it is typically the rms value of the data from the mic in dB FS when driven by a 94 dB SPL calibrator with the Windows volume control set to 1.0, but there can be some ambiguity as to whether the rms level of a full scale sine wave is treated as -3 dB FS or 0 dB FS, and the effect of a 1.0 volume setting can be different between Windows XP (which I think the factory uses) and Windows 8. One option could be to simply copy the Dayton line across as supplied so that the files retain the same info.
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post #256 of 368 Old 02-25-13, 12:31 AM
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Re: Cross-Spectrum Microphone Calibration Service - USA

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I think it is in the first line of the Dayton cal files, e.g.

"Sens Factor =-23.555dB, SERNO: 1280303"
You are correct, I forgot that I deleted that line from the test files I downloaded because it screwed up my import script.

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For these USB mics it is typically the rms value of the data from the mic in dB FS when driven by a 94 dB SPL calibrator with the Windows volume control set to 1.0, but there can be some ambiguity as to whether the rms level of a full scale sine wave is treated as -3 dB FS or 0 dB FS, and the effect of a 1.0 volume setting can be different between Windows XP (which I think the factory uses) and Windows 8.
That ambiguity is exactly what prevents me from offering sensitivity measurements for USB mics. There are ways to confirm it, say by sticking the USB mic in the same field as one of my reference mics + meters and seeing if plugging in the factory (or other) sensitivity numbers into ARTA/etc give the same SPL results, but that's enough of a pain to not be worth the effort for me.

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One option could be to simply copy the Dayton line across as supplied so that the files retain the same info.
Yeah, but the implication would be that I endorse those factory sensitivity number, which I don't. Not to say they're wrong (all indications are that they're at least pretty close), but if my name is on it, I want to be able to measure it directly.
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post #257 of 368 Old 05-01-13, 09:10 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

For Cross - Spectrum Calibrated Dayton EMM-6 and Behringer ECM8000 microphones with:

0 degrees calibration files
45 degrees calibration files
90 degrees calibration files

Can you describe the senarios (when they should be used) for each of these calibration files?

Which mic orientation should/ideal be used for each senario/file?

Thanks in advance
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post #258 of 368 Old 05-01-13, 09:32 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

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For Cross - Spectrum Calibrated Dayton EMM-6 and Behringer ECM8000 microphones with:

0 degrees calibration files
Loudspeaker measurements, microphone pointed directly at speaker.

Quote:
90 degrees calibration files
Room acoustics/calibration measurements, microphone pointed straight up at ceiling or tilted slightly toward front speakers.

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45 degrees calibration files
For experimentation purposes.
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post #259 of 368 Old 05-02-13, 06:26 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

Quote:
Phillips wrote: View Post
For Cross - Spectrum Calibrated Dayton EMM-6 and Behringer ECM8000 microphones with:

0 degrees calibration files
45 degrees calibration files
90 degrees calibration files

Can you describe the senarios (when they should be used) for each of these calibration files?

Which mic orientation should/ideal be used for each senario/file?

Thanks in advance
My suggestion: For room measurements, pick one and use it for all measurements. Otherwise it becomes difficult to compare measurements taken at different times, under different conditions. For close speaker measurements, always use 0 degrees.
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post #260 of 368 Old 05-06-13, 10:58 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

Effectively immediately, we're no longer selling calibrated ECM8000 mics. We will continue to offer Dayton EMM-6/UMM-6 mics and Galaxy CM-140 sound meters (and very soon, UMIK-1 mics).

To make a long story short: ECM8000 quality has declined to a point where they are utter and I'm sick of messing with them.
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