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REW Author
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1st Problem:
On both Mac (REW v5) and Windows (latest REW beta), the SPL readings appear to be way off. In my quiet apartment, the UMIK reports about 65-75 dBSPL, C-weighted. I have a standalone SPL meter which reads about 10-15 dB below this. I would tend to trust the calibration on the UMIK over my cheap SPL meter, but I think the UMIK reading is way to high for just the ambient noise level. These measurements were taken with the UMIK cal file loaded in to REW in both Mac and Windows.
The OS X version of REW (V5.0) does not know about UMIK-1, SPL readings for OS X need to be calibrated using the procedure in the help (Calibrating the SPL Reading).

For the Windows version (assuming V5.01 beta 11 or later) did REW automatically detect the UMIK and ask if you wanted to use it? If not, please set the input device back to default on the REW soundcard preferences then shut down and restart REW, it should ask if you want to use the UMIK-1 and then ask for the cal file. If you had already done that, please post a screenshot of the REW soundcard preferences dialog.

2nd Problem:
When using the UMIK and REW on Mac, REW reports that the UMIK is clipping when taking measurements. This happens even when using my Macbook speakers for output, so I'm sure the sound pressure is not actually exceeding the range of the UMIK. I tried adjusting the UMIK level in the Mac OS MIDI Setup, but it did not appear to have any effect on the results. I am using a 128k sample length for these measurements.
Is the UMIK selected as the default device and REW set to use the default input?
 

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Yes, but I need to get hold of a way to run the latest OS X release first (which I'm working on). There are likely to be limitations in the SPL calibration though - under Windows REW can read the input volume control setting and take it into account in the SPL figure, but under OS X the Java runtime does not provide access to the volume controls. There is a chance that the Oracle Java runtime has addressed that, however.
 

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Thanks John. This Mic and it's simple plug and play (at least for Windows) has persuaded me to get into room measurement. I am sure that many who were sitting on the fence will also jump in.
 

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Hi John,

Thanks a lot for your reply.

The OS X version of REW (V5.0) does not know about UMIK-1, SPL readings for OS X need to be calibrated using the procedure in the help (Calibrating the SPL Reading).

For the Windows version (assuming V5.01 beta 11 or later) did REW automatically detect the UMIK and ask if you wanted to use it? If not, please set the input device back to default on the REW soundcard preferences then shut down and restart REW, it should ask if you want to use the UMIK-1 and then ask for the cal file. If you had already done that, please post a screenshot of the REW soundcard preferences dialog.
Yes, REW did automatically detect the UMIK on the Windows version. I clicked yes and loaded the cal file. I did not change any other preference settings away from their default. Unfortunately, I was borrowing a Windows laptop and can't get a screenshot for you.

Is the UMIK selected as the default device and REW set to use the default input?
On the input clipping when using REW on Mac - I was previously changing the input device in the REW soundcard preferences from 'default' to the UMIK, then running sweeps. Now, I tried selecting the UMIK as the default input device in the Mac OS System preferences, and then starting REW. I now receive an error when REW starts, which says: "Unable to access the selected device
javax.sound.sampled.LineUnavailableException: Unexpected Error". I am using Mac OS X 10.8.2 on a 2010 Macbook Pro.

Maybe REW was never actually using the UMIK (rather, built-in mic instead) when I was experiencing the clipping in Mac OS?
 

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Ok I know this has been asked many times, but I'm just trying to make sure I have the mic configured properly for the SPL meter in REW and also to reflect correct spl reading on FR plots. Everything is setup and working, but the spl measurements seem much higher than I would have guessed. I have a PC with windows 7, hdmi out to receiver, miniDSP usb mic in, and REW beta 12. The 2 volume adjustments for input volume of the mic are the windows mic volume control and the input volume control in REW. What should I have both of these values set at for correct readings? Thank you
 

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The 2 volume adjustments for input volume of the mic are the windows mic volume control and the input volume control in REW. What should I have both of these values set at for correct readings?
They should both be showing the same thing, except the Windows control goes from 0 to 100 and the REW control from 0 to 1, so 53 on the Windows control (for example) should be appearing as 0.53 in REW. If they are both showing the same then it doesn't matter too much what they are set to, anywhere between 0.5 and 1.0 should produce the same SPL reading for the same signal. If you are measuring 'normal' levels (not trying to measure maximum output of your sub, for example) set the control to 1.0 in REW or 100 in Windows, but if you need to measure levels above 110dB use 0.53 / 53.
 

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They should both be showing the same thing, except the Windows control goes from 0 to 100 and the REW control from 0 to 1, so 53 on the Windows control (for example) should be appearing as 0.53 in REW. If they are both showing the same then it doesn't matter too much what they are set to, anywhere between 0.5 and 1.0 should produce the same SPL reading for the same signal. If you are measuring 'normal' levels (not trying to measure maximum output of your sub, for example) set the control to 1.0 in REW or 100 in Windows, but if you need to measure levels above 110dB use 0.53 / 53.
Awesome, thank you John
 

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The OS X version of REW (V5.0) does not know about UMIK-1, SPL readings for OS X need to be calibrated using the procedure in the help (Calibrating the SPL Reading).

Hi Everyone,

I am having some issues with my UMIK-1 and hope some of you might have some helpful advice.

1st Problem:
On both Mac (REW v5) and Windows (latest REW beta), the SPL readings appear to be way off. In my quiet apartment, the UMIK reports about 65-75 dBSPL, C-weighted. I have a standalone SPL meter which reads about 10-15 dB below this. I would tend to trust the calibration on the UMIK over my cheap SPL meter, but I think the UMIK reading is way to high for just the ambient noise level. These measurements were taken with the UMIK cal file loaded in to REW in both Mac and Windows.
For the Windows version (assuming V5.01 beta 11 or later) did REW automatically detect the UMIK and ask if you wanted to use it? If not, please set the input device back to default on the REW soundcard preferences then shut down and restart REW, it should ask if you want to use the UMIK-1 and then ask for the cal file. If you had already done that, please post a screenshot of the REW soundcard preferences dialog.

Is the UMIK selected as the default device and REW set to use the default input?


I just got my umik1 and I'm having the same problem.
REW recognized the mic and asked if I want to use it and then asked for the cal file which I loaded.
When using the spl meter I'm getting 70-75 db of ambient noise level, which can't be right.

I have an aperion audio spl meter, which as far As I know is the same as the analog RadioShack meter, and when setting that to the lowest db scale (60db) the needle doesn't even move.

I don't have accesses to the mic right now but I will post a screenshot of the sound card preferences tomorrow.

Looking forward to messing around with REW and the minidsp. That's a winning combination :clap:
 

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I just got my umik1 and I'm having the same problem.
Please also include which OS you are running and which version of REW, and have a look at the REW log files (location is shown in the Help -> About box) and see if they contain an entry that states a figure for Mic Sensitivity, and what that figure is.
 

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Please also include which OS you are running and which version of REW, and have a look at the REW log files (location is shown in the Help -> About box) and see if they contain an entry that states a figure for Mic Sensitivity, and what that figure is.

I'm running REW 5.01 beta 12 build 2849.

OS is Windows 7 64 bit.

There's the following entry in the logs:

??? 10, 2013 5:00:48 PM roomeqwizard.CalData calFileLoader
INFO: Mic sensitivity -15.188 dB

That is also the sensitivity value in the cal file.
 

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Thanks for that. Please try setting the input volume control in REW to 1.0 and see if that changes the SPL reading you get when the room is quiet, please also let me know approximately what value is shown in the DB Fs gauge below the SPL figure, it will be varying so a rough figure is fine.
 

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The Mic in USB for audio in. If your computer has a HDMI connection, you can use that for audio out, to your amp or receiver.
 

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The Mic in USB for audio in. If your computer has a HDMI connection, you can use that for audio out, to your amp or receiver.
Thank you for explaining this mate. Much difference to just using the normal left/right aux in on the AVR?

I wonder how this microphones accuracy compares to the Premium+ calibrated Cross-Spectrum Dayton EMM-6 that i currently own and if it's worth getting the UMIK-1? Well i guess we'll only know for sure with time. :)

It sure is handy not having to find and set the external soundcard/preamp and attach adapters each time i want to do a measurement. :clap:
 

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Just did a quicky test with umik-1 Mic and a borrowed radio shack analog spl meter. Windows 7 32-bit, hdmi out audio, REW beta 13. Put the spl meter in REW on C-weighted, and well as the radio shack meter. The readings from both were mostly within 2 db at the frequencies I tested from 20hz-20,000hz. I also changed the mic input volume in REW to different levels and all spl readings stayed the same at given frequencies. Thanks for all your work John, I love this software.
 

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I have purchased a UMIK-1 and has done some measurements in REW (beta 13) under Windows 7. The results are very strange compared to measurements with my Behringer ECM8000. The frequency response curve rises with more than 30 dB from 40 Hz to 1.5 kHz (I've tried both with and without the UMIK calibration file). This is with subs and Audyssey MultEQ XT32 calibration enabled, so I would expect a pretty flat curve down to about 30 Hz. The ECM8000 curve is much flatter. See attached image for measurement curves.

Any help on what might be the problem is much appreciated.
 

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Is it possible that your sound card's output stage has that much low-frequency rolloff? If it does, and you have run sound card calibration for use with the Behringer measurement mic, that rolloff would not show up in the upper curve but would show up in the lower curve which does not include any calibration for the sound card output stage. That is the only explanation that I can think of.

Note: That is a lot of rolloff, perhaps there is some other signal processing going on in the computer that you are not aware of.
 

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Is it possible that your sound card's output stage has that much low-frequency rolloff? If it does, and you have run sound card calibration for use with the Behringer measurement mic, that rolloff would not show up in the upper curve but would show up in the lower curve which does not include any calibration for the sound card output stage. That is the only explanation that I can think of.

Note: That is a lot of rolloff, perhaps there is some other signal processing going on in the computer that you are not aware of.
I don't think that's the problem, I'm using the SPDIF output of the Realtek sound device on my motherboard and all effects are turned off. It's the same output I use for all sound playback in Windows. I don't use any soundcard calibration file in REW, neither for the Behringer or the UMIK.
 
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