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I just got the new Parts Express 2013 catalog and they have a new measurement mic listed. It is not showing up on the website yet so it's not available to order but in the catalog it lists for $88.26. It looks like the Omnimic but it instead black.

I took a pic of the product page:



I am thinking this will work with REW?
 

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Looks like it could possibly be an excellent candidate for use with Room EQ Wizard. One important thing to find out: does each individual unit come with its own a factory-supplied calibration curve? Calibration microphones in this price range typically do not, so if this one does, that would be a real bonus.

As has been discussed in other threads, there are places where a microphone like this can be sent in and calibrated, giving the user a calibration curve to use with Room EQ Wizard or other such software packages, if not already supplied. Absent individual calibration, it could still be used to get rough starting-point curves for a system, but for any kind of refined work, individual calibration is a must.

Assuming basic performance specs like noise level and distortion are good, and there is no reason to believe they wouldn't be, this unit with its USB connection might be a nice measurement microphone for someone who doesn't have a good quality audio interface. Could be a real value unit for someone just getting into speaker/room measurements and treatments.

Edit: A correction about less-expensive measurement microphones and individual calibration curves - Dayton Audio's EMM-6 measurement microphone does come each with its own factory calibration curve. They retail for $80, Parts Express carries them for under $50, on sale at the moment of this writing for under $40, quite a deal, and the model appears to have very nice specifications overall. A unique text calibration file can be downloaded from Dayton's website corresponding to the microphone's serial number. The new UMM-6 is most likely (educated guess) based on the EMM-6, and as such may very well feature individual calibration files available, too.
 

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Good point, we will have to wait until it is available to purchase and find out if it will come with a calibration file. I would certainly hope so with the price there asking.

One thing I remember about REW is you need to connect the audio output of your computer for the test tones. I wonder if it is possible to make a CD like Omnimic comes with so you only have to connect the USB mic and insert the CD and your ready to measure. This sure would make REW a lot more user friendly.
 

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One thing I remember about REW is you need to connect the audio output of your computer for the test tones. I wonder if it is possible to make a CD like Omnimic comes with so you only have to connect the USB mic and insert the CD and your ready to measure.
I am not sure if REW needs to be generating the sweep in order to be "in sync" with it somehow, or if it can follow a sweep from any source and make proper sense of it. A good question for John, the programmer.
 

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REW needs to generate the sweep itself presently, but the ability to measure with external sweeps is on my ToDo list.

MiniDSP have just come out with a new USB mic, UMIK-1, which is individually calibrated, see http://www.minidsp.com/products/acoustic-measurement/umik-1. It's a neat package, I've tried out a prototype which works very well - all the benefits of a calibrated measurement mic without the hassle of needing a preamp with phantom power or having to go through soundcard calibration. I'm currently making some tweaks in REW to make measuring with the UMIK-1 even easier.

Umik1-thumb.jpg
 

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Nice to see some new simple USB mics.

Curious if calibrating them would be harder, as I imagine that calibrations for most mics that require phantom power actually use the raw signal from the mic..

John - Cool to see you tweaking REW for the MiniDSP mic. :)
 

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just read the minidsp december newsletter and googled for the new umik-1 mic for any review or comparison with a professionally calibrated mics.

at USD$75 plus some shipping it should be the cheapest option to get a calibrated mic to use with REW. and it's specced to be flat till 5hz (after correction). by skipping phantom power, mic preamp or a new soundcard that supports condenser mic this should easily be the best deal so far.

i was previously considering the calibrated galaxy cm-140 (just to skip phantom power and mic pre) but after looking at the posted calibration result i decided to cancel. the meter have too much attenuation at the low frequency that it's not exactly precise anymore. -6db down at 20hz, -12db down at 10hz and -22db down at 5hz. it's only flat to 100hz. :gulp:

this umik1 shows much potential. it's only a couple db down at 5hz.
 

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I'm definitely in for more details. I haven't gotten around to picking up a USB-powered preamp, so this comes right at the right time.
 

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Another plus for the UMIK-1 is the cal file includes sensitivity calibration, which the next release of REW will use to provide calibrated SPL readings from the mic - no SPL meter needed.
 

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the only gripe is that there's no 90 degrees off axis correction.
if i remember correctly there should be some slight difference on axis and off axis measurement. higher attenuation at the high frequency.
 

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That new mic for MiniDSP looks like the hot ticket.

Thanks a ton for responding to this thread John, if not I would have never known about it and the work your doing to make it work with REW :hail:

This is what I have been waiting for.
 

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the only gripe is that there's no 90 degrees off axis correction.
if i remember correctly there should be some slight difference on axis and off axis measurement. higher attenuation at the high frequency.
I may be able to assist with that. ;)

The wholesale pricing for UMM-6 mics is pretty reasonable, so I may be able to offer CSL "Basic+" (0-degree, 45-degree and 90-degree) versions of this mic at a slight premium over the PE pricing. First thing is that I have to get my hands on one and see how well it works with my measurement rig - I'm really hoping that the capsule end is 1/4-inch or 3/8-inch diameter and not some non-standard in-between size like the OmniMic microphone.

edit: gah, it is a non-standard size (0.315")
 

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I purchased the miniDSP mic. It shipped today. For any one interested here is my calibration file. FYI you can look at the different calibration files by simply modifying the serial number in the link. I did some comparing to other mics and there are definitely some highly accurate mics out of the box, more so than mine.

http://www.minidsp.com/images/umik/Umik-1/7000137.txt

If you don't mind spending the time one could consider asking miniDSP for a particular serial number mic. I wasn't aware that all the files were available online when I placed my order...

I look forward to using the mic with REW for EQing my sub and getting a baseline EQ for our church PA system.

Daniel
 

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Discussion Starter #14
So the MiniDSP UMIK-1 mic will work with REW right now or do we have to wait for a REW update?
 

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My UMM-6 arrived today. I threw is on the rig to see what kind of frequency response curve I would get and to compare it with the factory Dayon curve. To say I was shocked is putting it mildly:



The two curves aren't even close :(.

This may be a problem on my end, I know that ARTA has problem with taking transfer function measurements between two different sound card devices so I'll experiment a little more with Holm Impulse to see if my results are consistent.

In the meanwhile I'll have to wait a little bit before offering these for sale.
 

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I spent the last three hours trying a variety of cal methods and everything I get is consistent with the plots above.

I'll pick up a UMIK-1 in the next week or two and see what I get with that mic.

edit: have there been any 3rd party measurements of the UMM-6 or UMIK-1?
 

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Discussion Starter #18
So can anything be done about the UMM-6 to improve it or should we just stay away?
 

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So can anything be done about the UMM-6 to improve it or should we just stay away?
The thing is, I don't know how Dayton is measuring their mics. Dayton worked with Bill Waslo to developed the Omnimic system so they clearly have access to smart guys; maybe they accounting/correcting for something in their measurement that I'm not (and should be). On the other hand, I can replicate the results from two NIST traceable labs to within 1 dB (reconfirmed today) with my setup so I think my data is good.

Without knowing what they are doing, all I can do is plot two curves generated from the same mic and wonder what the is going on here...

The thing of it is, I'd like to start selling the UMM-6 myself, but I can't justify doing it when there's a 5 dB difference between what I get and the factory curve without understanding why. I get slightly different data with my Dayton EMM-6 measurements, but not *5* dB different!
 

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The thing is, I don't know how Dayton is measuring their mics. Dayton worked with Bill Waslo to developed the Omnimic system so they clearly have access to smart guys; maybe they accounting/correcting for something in their measurement that I'm not (and should be). On the other hand, I can replicate the results from two NIST traceable labs to within 1 dB (reconfirmed today) with my setup so I think my data is good.

Without knowing what they are doing, all I can do is plot two curves generated from the same mic and wonder what the is going on here...

The thing of it is, I'd like to start selling the UMM-6 myself, but I can't justify doing it when there's a 5 dB difference between what I get and the factory curve without understanding why. I get slightly different data with my Dayton EMM-6 measurements, but not *5* dB different!
It seems like that would be a discrepancy that they would want to correct/clarify, especially if it is just something deliberate they did that is helpful. Is there anyone at PE you could reach out to that would have the technical expertise to help add insight to this?
 
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