Cross-Spectrum Microphone Calibration Service - USA - Page 8 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #71 of 368 Old 07-12-09, 09:17 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

A couple of things:

1. If you ask me a question here and I don't respond within 24-hours, shoot me an email directly and I'll respond here. For some reason I don't always get the thread update emails.

2. Here's a head's up - I offered to do freq-response curves at additional angles for my calibrated mics for free. However, it's become a bit of a hassle to keep track of the various special orders. As a result, I'm going to change things a bit - as of August, I'm going to offer 4 mic models: a) "Basic" with 0-deg freq response for $85, b) "Basic-Plus" with 0/45/90 deg for $90, c) "Extra" with 0-deg freq response, polar, noise floor, and sensitivity for $100 and d) "Extra-Plus" with the "Extra" package + 0/45/90 deg for $110. On the plus side, I'm going to do freq-response down to 5 Hz by default.

This is going to be a price increase but on the plus side, I'll try to stock up on these models so there won't be a wait for people who want the 45/90-deg measurements.

However, I will still do the extra measurements for free for orders placed before Aug 1, so if you want to save some money, place your order before then.

Now on to questions:

Quote:
If we were going to do so, would it not make sense to calibrate the mic/preamp as a system, since there may be more phase effect in the combination than just in the mic?
For my measurements, it doesn't matter since I don't measure phase .

Quote:
I see you also calibrate the Galaxy CM-140, but along with selling pre-calibrated ECM8000, do you also sell pre-calibrated CM-140's?
I don't sell pre-calibrated meters and I don't imagine I ever will because there are potential liability issues on my end if people purchase it from me for the purpose of using it in a legal setting. However, if you buy a meter, you can have it shipped directly to me, and I'll calibrate it and send it on to you which should at least save a couple of bucks in shipping costs as well as a couple of days of time.
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post #72 of 368 Old 07-13-09, 06:27 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

Quote:
Anechoic wrote: View Post
as of August, I'm going to offer 4 mic models: a) "Basic" with 0-deg freq response for $85, b) "Basic-Plus" with 0/45/90 deg for $90, c) "Extra" with 0-deg freq response, polar, noise floor, and sensitivity for $100 and d) "Extra-Plus" with the "Extra" package + 0/45/90 deg for $110. On the plus side, I'm going to do freq-response down to 5 Hz by default.
Do the Basic and Basic-Plus not include 1K sensitivity? Seems like everyone would need that.
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post #73 of 368 Old 07-13-09, 07:41 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

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Do the Basic and Basic-Plus not include 1K sensitivity? Seems like everyone would need that.
Correct, the Basic and Basic-plus do not include 1 kHz sensitivity. I thought more people would want sensitivity but it turns out that very few people care about - in fact more people want the polar response than the sensitivity.
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post #74 of 368 Old 07-14-09, 08:46 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

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Correct, the Basic and Basic-plus do not include 1 kHz sensitivity. I thought more people would want sensitivity but it turns out that very few people care about - in fact more people want the polar response than the sensitivity.
That's amazing. How are they measuring SPL? An RS meter that may or may not be within 3dB?

On another subject, can you calibrate above 24K for an extra charge? Many people are using 96K sound cards with a nominal 48K capability so it would be nice to have a general idea what the mic is doing up there, even if the calibration isn't perfect.
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post #75 of 368 Old 07-14-09, 08:51 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

Are people using the ECM8000 to measure SPL? I assumed most people were just using them for freq response curves.

The problem with >24kHz measurements is that I don't have calibration curves for my reference mics that go that high. The next time I send in my ref mic for calibration I'll ask them to push the curve out to 40+kHz and then maybe I'll offer the service for an extra charge.
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post #76 of 368 Old 07-14-09, 09:52 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

ARTA (along with some other programs, don't know about REW) has a setup routine where you calibrate your mic preamp and sound card with tones and a voltmeter so you can do your measurements in dB SPL if you can plug in the mic's sensitivity.
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post #77 of 368 Old 07-14-09, 10:09 PM Thread Starter
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Re: Cross-Spectrum Microphone Calibration Service - USA

Quote:
Dennis H wrote: View Post
That's amazing. How are they measuring SPL? An RS meter that may or may not be within 3dB?
Quote:
Anechoic wrote: View Post
Are people using the ECM8000 to measure SPL?
Some will use the RS meter, some the Galaxy CM-140 and others the ECM8000. SPL is not that terribly important. For level matching, most receivers and processors have Audyssey or equivalent for setting up the system anyway.

If you wanna just see how loud it will get, for whatever that may be worth, getting within 3db should be plenty sufficient, unless someone really has an OCB about being the SPL king, like the kids in the car stereo crank off contests.
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post #78 of 368 Old 07-14-09, 10:52 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

I know that you can do SPL measurements with the ECM8000 (I am an ARTA user & FWIW a Type 1 mic + ARTA gets you the same results as a Type 1 meter) I was just curious if anyone is actually doing it.

Quote:
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Some will use the RS meter, some the Galaxy CM-140 and others the ECM8000. SPL is not that terribly important. For level matching, most receivers and processors have Audyssey or equivalent for setting up the system anyway.
which sounds about right.

The reason I do sensitivity measurements is so people can do measurements but no one (outside of pros) really seemed to care. Interesting...
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post #79 of 368 Old 07-15-09, 07:51 AM
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Re: Cross-Spectrum Microphone Calibration Service - USA

Interesting...
I use a calibrated meter for SPL (well, use to, but just let Audyssey do that adjustment now - sometimes comfirm with the meter, but really not necessary). For SPL, it is MUCH easier to just use a calibrated meter then a calibrated mic with computer/software (no setup time) IMO. As Sonnie mentioned, there are 'some' that want to know max spl (I prefer to keep my hearing). I have use my meter just out of curiosity to see where my dynamic peaks are hitting with normal dialog at 85db (meter showed 109db on peaks), but only because I wanted confirmation that peak levels do not sustain long enough for hearing damage.

Ray

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Happy Listening!!! Listen with an open mind and heart!!!

Last edited by cavchameleon; 07-15-09 at 06:09 PM. Reason: correction
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post #80 of 368 Old 07-15-09, 01:21 PM
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Re: Cross-Spectrum Microphone Calibration Service - USA

The crowd where I usually hang out is into designing speakers so having the levels calibrated is useful when you're mixing and matching drivers that may have been measured at different times and under different conditions. The most common way is to normalize everything to 2.83V/1m when you save the files.
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