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Old 13th September 2011, 01:03 PM   #1
spot is offline spot  Australia
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Default Which microphone to use for speaker analysis?

I'm looking at testing some speakers with speakerworkshop or some of the other software programs available. Is there a particular recommended microphone to use?
I'm not wanting to spend much, but am under the impression that common electret condenser microphone elements can be very good.
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Old 13th September 2011, 02:47 PM   #2
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How much (or little) is not much?
You can get a calibrated Dayton EMM-6 or Behringer ECM8000 for about US$100 from Cross·Spectrum Labs - Sound | Vibration | Engineering
E
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Old 22nd September 2011, 04:30 PM   #3
stoc005 is offline stoc005  United States
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Google "Wallin Preamp" and use a Panasonic wm-61a cartridge for the cheapest setup.
See: Mad About Sound | Microphone Preamplifier PCB v1.1 for a PCB for the preamp.
The ECM8000 is a very good choice and 54.99USD at Parts Express.
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Old 2nd October 2011, 12:40 AM   #4
metako is offline metako  Australia
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I already have an Akai electret mic - can any mic be calibrated to be used for measurement? If so, is there a way to calibrate a mic within Speaker Workshop? Thanks.
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Old 2nd October 2011, 01:56 AM   #5
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Any mic can be calibrated. Finding someone to do it will be tricky + costly. Note: that when they use the term "calibrate" they do not flatten the response of the mic, but give you a list of corrections (in dB) relative to a flat line from xHz to xkHz to be entered into your measurement data. E
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Old 2nd October 2011, 04:04 AM   #6
Ron E is offline Ron E  United States
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Quote:
Originally Posted by metako View Post
I already have an Akai electret mic - can any mic be calibrated to be used for measurement? If so, is there a way to calibrate a mic within Speaker Workshop? Thanks.
Measurement mics need to be omnidirectional. A directional (unidirectional, cardioid, anything but omni) mic changes frequency response depending on distance from the source.

You can check mic frequency response by measuring a tweeter that is fairly flat when mounted flush to a large baffle. Most electret mics have decent low frequency response, at least to 30Hz and some go lower, and are flat above that until their second resonance, which will perhaps be around 10-15k, depending on mic size. Larger diameter mics have lower resonances.
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Last edited by Ron E; 2nd October 2011 at 04:06 AM.
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Old 2nd October 2011, 05:35 AM   #7
gootee is offline gootee  United States
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I recently bought a Superlux ECM-999 measurement mic on ebay, new, for $74 + $10 shipping. It's a 1/2-inch condenser type and is omni-directional and supposedly very flat from 20 Hz to 20 kHz, according to the plots in the ad on ebay. It came with a hard case, windscreen, and stand mount hardware. It has a 3-pin XLR female connector jack in the base.

It does need a mic pre-amp, or some other way to supply the phantom power. I bought a new TubeMP mic preamp at the same time, for about $30, plus an XLR-male-to-XLR-male mic cable for input from mic to pre, and a guitar cable (1/4" male to 1/4" male) and a 1/4"-male-to-3.5mm-mono-male adapter for pre out to soundcard input, and it all seems to work very well. I've been able to start dabbling with ARTA.

Just FYI, the TubeMP mic preamp has XLR female and 1/4" female input connectors and XLR male and 1/4" female output connectors. It seems like a nice little unit, for the price. It does have a vacuum tube. And it has a lighted VU meter, and different gain range options and knobs for both input and output, and 48V phantom power that can be switched on or off.

Last edited by gootee; 2nd October 2011 at 05:44 AM.
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Old 2nd October 2011, 12:46 PM   #8
metako is offline metako  Australia
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Thanks for all the above info. The Akai mic is in a storage locker so I'll have to try to find it and check the spec sheet to see if its omnidirectional-got a feeling its cardioid. Already got a M-audio Duo mic pre, gootee but that TubeMP pre sounds like a huge bargain.
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Old 2nd October 2011, 02:04 PM   #9
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For measurements, you want a mic pre that is as straight as possible. Based on tests I saw on other M-audio equipment, I suspect it will be 20-20KHz +/- a fraction of a dB. Still, it would be a good idea to measure its FR before you use it. Easy to do with the same software you use for measuring speakers. Just feed the attenuated output signal generated by your measuring software into your mic input and do a sweep.

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Old 3rd October 2011, 12:16 PM   #10
metako is offline metako  Australia
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Thanks Vacuphile, will do as you suggest. Good to hear the M-audio may a straight response.
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