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Old 26th August 2003, 01:01 AM   #11
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Quote:
So, what's the deal with "calibrated" microphones?

Is a calibrated microphone an ordinary microphone that's been calibrated somehow? And if so, how? Does one adjust the microphone itself... or what?
Hi Dave,

"Calibrated microphone" usually means that it`s sensivity versus frequency is measured against a known reference microphone (hence no, the mic itself is not adjusted).

Sometimes, in case of PC-based measurement systems the deviations in performance of the two mics can be recorded, stored on disk and fed into the software for automatic compensation. In regard to frequency response, the measurement system now shows results as it would work together with the reference mic.

Reference microphones are highly costly (up to a couple of k$) and very precise devices and their linearity of frequency response and sensivity (among other things) have to meet strict calibration standards . Search the web for Brüel&Kjaer, ACO Pacific, Larson Davis to name a few.

There are other ways to investigate the calibration of a mic. element (also usually not over the entire frequency response but at one or several discret frequencies). One is a so called "Sound-Level-Calibrator", the other is a "Pistonphone" (actually there are even more methods). Somewhat simplified both are some sort of speakers basically which are adapted to the microphone and which put out a precise "calibrated" sound level.
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Old 26th August 2003, 01:02 AM   #12
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If you're using TrueRTA, just get a Behringer ECM 8000 measurement mic. It costs around $30 from www.americanmusical.com.

The Nehriner mic is remarkably accurate for such a cheapie anyway, but TrueRTA includes a calibration file for it in any case.

Cheers

Steve
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Old 26th August 2003, 01:05 AM   #13
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Quote:
Originally posted by JasonL
i wish i could find a audio control one. i miss those. it was a "eq" and a spectrum analyzer in one
http://shop.store.yahoo.com/avshopper/243.html
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Old 26th August 2003, 01:07 AM   #14
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Do you or any one have a schematic for just the display part..? i want to build just the display part. if not ill have to buy the whole thing heh.
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Old 26th August 2003, 01:08 AM   #15
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Quote:
Originally posted by sfdoddsy
If you're using TrueRTA, just get a Behringer ECM 8000 measurement mic. It costs around $30 from www.americanmusical.com.

The Nehriner mic is remarkably accurate for such a cheapie anyway, but TrueRTA includes a calibration file for it in any case.

Cheers

Steve
Will I need a microphone preamp with it? My soundcard is a SoundBlaster Audigy II, if that matters. (I am totally ignorant about this stuff, but I guess you figured that out.)
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Old 26th August 2003, 01:19 AM   #16
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Default this will work

these HP 3581 "wave analyzers" will really fit the bill -- they are very sensitive, have excellent resolution and have been pretty cheap on EBay of late -- anywhere from $50 to $120. The unit has a built in sweep generator and very fine resolution. You can also get a companion plotter which accepts the 0 to 5 VDC out and graph the results.

Here's the link to the HP3581 manual I put on my website:http://www.tech-diy.com/hp3581.htm
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File Type: gif 3581_pic.gif (89.1 KB, 197 views)
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Old 26th August 2003, 01:25 AM   #17
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Quote:
Originally posted by JasonL
Like this..

http://cgi.ebay.com/ws/eBayISAPI.dll...&category=3271
Yeah, I started to bid on that one, but then I saw 10 negative feebacks. I've gotten stuck for about two grand worth of stuff buying from ebay. I don't know why I even bother looking at something that costs more than 50 bucks or so.
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Old 26th August 2003, 02:03 AM   #18
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Default Really good stuff...

Hey, guys... I had to comment, sorry for my entrance without invitation. I have that combo, True RTA and Behringer ECM8000 in use... I made a small preamplifier to the mic and all is working very, very good. The level 4 with 1/24 oct RTA works perfect to our application,(to build speakers) and my curves got under a mat are very close to driver's factory measured response. The overall cost is very low, I recomend it.
Just my drop in the ocean.

Regards.
Hisatugo

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Old 26th August 2003, 02:48 AM   #19
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I use it straight into a Soundblaster MP3+ external card (I have a laptop) so you won't necessarily need a preamp.

You will need to supply it with phantom power though. I use a Behringer 602 mixer, which is $50 or so and has volume controls so it acts like a preamp if needed. The Behringer Shark is also cheap and good.

Cheers

Steve
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