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Would anyone know if the UMM-6 operates at 44.1 kHz sample rate, or only at 48 kHz? I can't find this information anywhere...
 

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Ah. Thanks Herb, perhaps it only operates at 44k1 then. I guess that's what should have asked, what samples rate or rates does it run at.
 

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Hmm... I have been using it with 48khz selected on REW since I received it. Just changed it to 44.1khz and that works fine, too.
Is the mic actually working at 48kHz under REW, or is REW resampling the output? No matter what sample rate I use inside ARTA, I always get a sharp rolloff at 21-22 kHz which is why I thought the output was fixed at 44.1 kHz.
 

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Is the mic actually working at 48kHz under REW, or is REW resampling the output? No matter what sample rate I use inside ARTA, I always get a sharp rolloff at 21-22 kHz which is why I thought the output was fixed at 44.1 kHz.
Good question. I measure from 0-20k with either setting. How would you suggest I measure and what would I look for to know if REW is resampling?

I always change the playback device in Windows to match the 44.1/48 setting.

My test rig is actually set up and ready to go if you'd like me to perform specific tests just let me know.

--J
 

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The "acid test" seems to be the impulse response. Could I ask if either of you have examined that, when taking a 44k1 sweep, does it look reasonable for the DUT?

Herb, perhaps what you are seeing in the UMM-6 is an anti-aliasing filter? Not switched by sample rate. On the Mac an input device will tell you what sample rates it will run at, I don't know right now how to get the same info on Windows.
 

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Herb, perhaps what you are seeing in the UMM-6 is an anti-aliasing filter? Not switched by sample rate. On the Mac an input device will tell you what sample rates it will run at, I don't know right now how to get the same info on Windows.
Okay, I found a setting deep inside the Win 7 sound control panel that does switch sample rates and it does seem that the UMM-6 operates at both 44.1 and 48 kHz. I was previously calibrating them under Win XP (I just got a Win 7 machine over the weekend) and I couldn't find a way to switch the sample rate, but it looks like I was measuring it on the 48 kHz setting (I mistakenly thought I was calibrating it at 44.1 kHz).
 

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I was previously calibrating them under Win XP (I just got a Win 7 machine over the weekend) and I couldn't find a way to switch the sample rate, but it looks like I was measuring it on the 48 kHz setting (I mistakenly thought I was calibrating it at 44.1 kHz).

Would this have any effect on the calibration files?
 

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Would this have any effect on the calibration files?
It shouldn't, the calibration files are the "best case" - if you're running it at 48 kHz, you have the full data set. If you're running it at 44.1, the data is being rolled off at (or before) 22.5 kHz, but up to that point it's accurate.
 

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I have been wanting to get a mic for use with REW for some time now and I was going to order the UMIK-1 when it became available but since reading the issues regarding the Cal files, sensitivity and it not being able to monitor below 20hz is the UMM-6 the best option under $200 for a USB mic currently?
 

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Has anyone been able to get the UMM-6 to work with REW 5.0 under Win 7? The mic works fine with ARTA and HolmImpulse, but not with REW. I'm presuming I've missed a configuration option someplace.

edit: nevermind I figured it out.
 

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Has anyone been able to get the UMM-6 to work with REW 5.0 under Win 7? The mic works fine with ARTA and HolmImpulse, but not with REW. I'm presuming I've missed a configuration option someplace.

edit: nevermind I figured it out.
Hi Herb,
I'm running the latest beta version of REW on a Win7 Laptop - and the UMM-6 works just fine. It was recognised the first time I connected it, and appeared in the Sound panel within Control Panel. When I've next got the laptop out I'll have a look for the sample rate selection you mentioned earlier.
So far the 1kHz (and above) spikes have not affected my measurements - as I am measuring well above the noise floor.
It's great to know that the measurements actually mean something at last, absolute (calibrated) not just relative.
Regards, Mike
 

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One aspect of the UMM-6 I was just made aware of - it apparently has a pretty high noise floor (around 50-52 dBA). For comparison, the typical noise floor range of the EMM-6 is ~30-34 dBA and for the ECM8000, it's ~ 33-40 dBA. The noise floor for my Type 1 mics is around 15-17 dBA.
Following up on this, here is a comparison of the noise floors of a UMM-6, an EMM-6 and a UMIK-1 microphone:


All three mics have been level calibrated, but I did not adjust any of the input settings to try to optimize any of the three mics. I'll let the plot speak for it self, but my takeway:

- when looking at A-weighted noise floor, the UMIK-1 is about 49 dBA, the UMM-6 about 53 dBA and the EMM-6 about 33 dBA. Despite the high-order harmonics of the UMM-6 having a greater amplitude compared to the UMIK-1, the overall noise floor is not that difference since the A-weighting reduces the influence of higher frequencies. The spikes at 1 and 2 kHz for the UMIK-1 and UMM-6 are within a couple dB of each other.

- IMO, the UMM-6 is absolutely not usable for high-frequency distortion measurements. The UMIK-6 is only mostly not useable for high-frequency distortion measurements.

- just a note: the 120 and 240 Hz spikes on the EMM-6 graph are caused by the AC power supply of my Presonus Firebox, when I connect the mic to battery-powered sound meters, those spikes aren't there.

- as I said before, both mics should be fine for most measurements provided you stay 10 dB above the noise floor. I suppose it may be possible to optimize this a bit by experimenting with the sound control panel volume settings, but I don't have the time to experiment with that right now.
 

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I've been thinking of trying out REW for quite a while, actually bought a UCA202 a while back and almost got started with it until I got distracted. After reading about the UMIK-1 and UMM-6 mics I'm thinking of one of those to get a better idea of things vs an old RS analog meter that I have.

I've read about the UMIK-1's calibration file oddities and might lean toward the UMM-6, but also read that the UMIK-1 is easier to setup w/ REW. How so? Does REW automatically pick settings for it or something like that? Also, I think I read something about a driver for UMM-6...Does it need one? Where do you get it?

BTW, my laptop is on Win7 and has HDMI.

Thanks!
 

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The UMM-6 instruction manual does not indicate the need for a driver for Windows. I believe it is plug-and-play.

I do not know if the UMM-6 calibration file contains the sensitivity calibration number like the UMM-1 does. If not, an extremely accurate SPL calibration is not necessary. You can use a smart phone SPL measurement app and get in the ballpark, which is all you need for most room measurement work.
 
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