Measurement mic calibrated

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Kjeldsen

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wintermute

wintermute

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Are you specifically wanting to purchase a mic for use with iPhone/iPad? or a more general mic? I wasn't 100% sure because one of them is for ipad/iphone and the behringer seems to be a normal sort of mic.

if you are after something for use on your computer the other two dayton emm6 mics might be a better option If you don't have a mic preamp then the usb one might be the better to go with.

Note I have not used any of them. I personally use a home-made mic with a panasonic WM60-AY capsule (no longer available) which is flat enough for my crossover design needs without a calibration file.

Tony.
 
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Kjeldsen

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I have a dedicated mic preamp for the PC and use Holmimpulse

The iphone/android mic is just a normal capsule for 1,5-3 volt power. The connector is special, and the headphone output might be an issue for high freq accuracy (it will most likely cause interference in the readings).

I already have a panasonic WM60 in a tube, but do not know where it's gone, and I would like to be sure that the results are good. I'm no expert and do not know if my phase readings are accurate or I also see the microphones phase contribution.

Basically I would like to have e mic that gives me accurate enough information on freq response, distortion and phase for DIY purpose.

I can use both genuine 48 volt phantom powered mics and 3 volt powers electret capsules with mini TRS jacks.

The preamp have ASIO drivers, so this way there should be no concerns for the input quality. An input without ASIO driver go through windows mixer, and I don't know the impact on measurements if any!
 
wintermute

wintermute

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I've not actually thought about whether the mic is adding phase shift to the measurements or not (I guess it is) but this should not matter. What is important is the relative phase between the drivers being measured. If the mic is adding phase offset, it will be the same for all measurements :)

I used non-asio drivers for years without any problem. My personal benchmark for whether the measurements are useful or not is to measure individual drivers (with a fixed mic location) and then measure again with crossover in place (nothing moved in the interim). Simulate the crossover with the actual driver measurements (you will need the in box impedance measurements as well) and compare the simulated response to the actual response. If they are a close match then your measurements are useful! :) If they are not then you probably still have some work to do.

Now where it does get tricky is if you are trying to shape the response at higher frequencies (maybe 5K and up), without a calibrated mic you may not get it right! The WM-60's were reputedly very flat (and certainly measurements of my tweeters closely resemble the manufacturers response curves). I accepted that there may be some error and my results have been good.

Since you already have a WM60 in a tube, perhaps you could find someone near you who has a calibrated mic and do a comparison. You can even generate your own calibration file if you do that.

Tony.
 
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Kjeldsen

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I'm not heading in that direction. I admire your experience, and ability to verify your measurements like that. Nut, I really would like to have a mic I can trust. Both Behringer and Superlux seems to have good consitensy in their older generations, but now they use other capsules that, are not that great.
Might go for some little more expensive mic with better overall reputation
 
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1audio

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The recording microphone is not too suitable to measurements. First, it is an electret, not an HV condenser mike. Not a big issue. Second its response is not extended and may be tuned fr better vocal sound. The Panasonic capsules are a really good deal for a measurement microphone. Even Earthworks uses them. However Earthworks selected the capsules they used and Panasonic is out of the microphone business.

You want a small mike diameter or you get errors from the physical size of the microphone. High frequency measurements with any microphone are subject to enormous errors from so many causes. Don't put a lot of value in the results. A "perfect" microphone won't overcome diffraction, reflections, air moisture etc.

Bruel & Kjaer's microphone handbooks have a lot of useful into. They can be found on the web.

I would get one of the microphones from cross spectrum if I needed a calibrated mike for a good price.
 
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Kjeldsen

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Mario Pankov

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Kjeldsen said:
I will se if I can get a used Beyerdynamic MM1 - if not I will just go for an uncalibrated superlux ecm999.
Click to expand...

Hej,

I had the ecm999 and today received back the MM1 from HiFi Selbstbau in Köln who calibrated it. As it was requested by the ecm999 buyer, I run a reference curve under specific conditions on one of my home speakers, which I still keep on my laptop. Can run a curve with the MM1 today, air temp and himidity are the same ( himidity is slightly higher though ) and post the two frequency responses so you can compare how much of a difference it is between the cheap Superlux and the MM1.

The bigger problem with cheap mics is not the frequency response, this can be calibrated. It is the distortion of the mic under specific SPL. Most cheap mics don`t even state their max SPL, neither at what distortion level it was measured ( eg. 1% or more ). This is serious because when you run a nearfield measurement at 0 degrees the SPL at the capsule, right at the dust cap of the driver, would be very high, typically above 120db. Second problem is the size of the mic tubing, cheap mics are large, where the MM1 for example or some of the B&K stuff is thin and very narrow.

Besides the issues above, an uncalibrated cheap mic would still produce reliable frequency and phase response in the 500-5Khz band. If you need it for home measurements, your gating frequency would usually be around 500-700Hz so not a big issue, the tweeter, if placed on a baffle, could also be ignored above 5Khz ( if measured alone it would have ragged response in the 5-8Khz band ). You`d need to buy a mic stand and measure properly - the mic`s axis should be the same as the stand`s arm axis to reduce reflections.
 
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