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-   -   Measurement mic calibrated (http://www.diyaudio.com/forums/equipment-tools/251904-measurement-mic-calibrated.html)

Kjeldsen 26th February 2014 07:11 AM

Measurement mic calibrated
 
What should I look for, or what are the pitfalls

Here are three different mic.

http://audiotransducers.com/en/20-me...nt-microphones

and the very cheap alternative

Elektret Mikrofon (kalibriert)

EDIT: One more candidate

http://www.parts-express.com/dayton-...droid--390-810

Kjeldsen 27th February 2014 09:02 AM

No one??? I really interested if the Behringer B-5 is worth the extra cost since it's a true condenser and not electret

Kjeldsen 27th February 2014 09:56 AM

If it matters I measure frequence, distortion and phase.

wintermute 27th February 2014 11:13 AM

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.

Kjeldsen 27th February 2014 11:23 AM

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 27th February 2014 11:43 AM

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.

Kjeldsen 28th February 2014 11:04 AM

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

TheShaman 28th February 2014 01:15 PM

Search for calibrated offerings of commercial products. E.g. this guy is pretty reliable.

1audio 2nd March 2014 05:49 PM

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.

Kjeldsen 3rd March 2014 07:37 AM

I know I shouldn't use a recording microphone.

Alle the cheap measuremnet are electret. The cheapest real condenser I have seen is the Behringer B-5.

All I have heard untill now is that I shuldn't really be botheres with the high freq. I will se if I can get a used Beyerdynamic MM1 - if not I will just go for an uncalibrated superlux ecm999.


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