Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 456 - AVS | Home Theater Discussions And Reviews
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post #13651 of 13662 Old Today, 02:23 PM
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Originally Posted by Alan P View Post
Try turning down the mic "volume" in Windows - right click the speaker icon in the system tray / Recording Devices / UMIK-1.
thanks Alan...isn't this against what the guide says though? the guide said to set the volume at 100. Is there a certain volume you would recommend?
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post #13652 of 13662 Old Today, 02:28 PM
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It does sound a bit odd yes. I suggest you go to check levels in the preferences screen and send a signal then change the level as Alan suggested and see what happens to the input level.

Double check you don't have some other audio manager app that is applying a boost too. I chatted with someone last week who had that problem. Retail computers are notorious for being chocka with bloatware after all.

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post #13653 of 13662 Old Today, 02:52 PM
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Originally Posted by 3ll3d00d View Post
Massively clipped UMIK-1 provides details on how to gain the gain, and SENS factor, of the mic itself. However, at stock settings, you should still be able to measure ~95-100dB without issues so that suggests a setting in your computer is the problem. You might want to open the mic to check the sensitivity but first I would look into your computer. How is the audio device configured in windows?
Matt, thanks for posting this link. I believe I saw the post back when it first started, but forgot about it. I think I'll mention it in the guide.
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post #13654 of 13662 Old Today, 02:53 PM
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Originally Posted by Alan P View Post
Try turning down the mic "volume" in Windows - right click the speaker icon in the system tray / Recording Devices / UMIK-1.
I don't think this is the right advice, Alan, sorry. It is just masking the problem. As the Guide recommends, the mic gain in Windows should be set to unity. This ensures everyone is on a level playing field.
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post #13655 of 13662 Old Today, 02:55 PM
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From a debugging perspective, it provides information though. Namely whether the computer settings on the input device react as you would expect.

I thought REW dealt with changes to the input level anyway, for the umik, so that it didn't matter? ie it also reads that value and adjusts accordingly.
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post #13656 of 13662 Old Today, 02:58 PM
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Originally Posted by AustinJerry View Post
I don't think this is the right advice, Alan, sorry. It is just masking the problem. As the Guide recommends, the mic gain in Windows should be set to unity. This ensures everyone is on a level playing field.
Any ideas jerry as to why my mic is clipping when taking measurements at 85db? Is there more info I should provide or other settings I should check? Thx
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post #13657 of 13662 Old Today, 03:03 PM
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OK, I just ran my own tests, with these results:

With AVR MV at -13, playing the Speaker Level pink noise test tone from the REW Generator at -12dBFS, the REW SPL meter registers 90dB, and the level indicator below the meter reads -16dBFS input signal level. Note that the AVR was in Stereo mode, and I was outputting the test signal to both left and right speakers simultaneously. And also note that my sensitivity parameter is 6.352. With these settings, I can measure up to a 103dB signal without clipping.

I also opened up my UMIK-1, and the dip switches are set to On-Off-Off, or 100, which is -12dB, according to the table on the mic's PCB. Matt, I recommend you open the UMIK-1 just to make sure your dip switch settings are the same. If your settings are the same, I am not sure what to recommend next. BTW, I have seen reference else where that some computers have a "Microphone gain setting" in the Windows Recording Device properties. You might want to check if you have such a setting and, if yes, make sure it is set to off. The Guide doesn't refer to a gain setting because I have never seen one on any of my computers.
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post #13658 of 13662 Unread Today, 03:05 PM
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Quote:
Originally Posted by 3ll3d00d View Post
From a debugging perspective, it provides information though. Namely whether the computer settings on the input device react as you would expect.

I thought REW dealt with changes to the input level anyway, for the umik, so that it didn't matter? ie it also reads that value and adjusts accordingly.
It may indeed adjust accordingly, but I stand by my advice--remove uncertainty by using the recommended settings.
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post #13659 of 13662 Unread Today, 04:19 PM
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Quote:
Originally Posted by AustinJerry View Post
I don't think this is the right advice, Alan, sorry. It is just masking the problem. As the Guide recommends, the mic gain in Windows should be set to unity. This ensures everyone is on a level playing field.
Sorry if I gave wrong advice, it was just the advice I was given (not here, in the ULF thread). I couldn't measure over ~118db with the mic at 100, I turned it down to 80 and now I can measure to ~135db (and yes, I realize most folks have no need to measure that high but I was doing max output/compression sweeps on my T-18s).

Are you saying the measurements I've taken with the mic set to 80 are invalid somehow? If so, that sux.

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post #13660 of 13662 Unread Today, 04:32 PM
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Originally Posted by jim19611961 View Post
I agree lower bass GD/Phase/FR anomalies are unachievable for most. But taking Jerry's graph, I think those >200hz are.
I thought an example to illustrate Markus's point, or what I think his point was, re the importance of early vs late arrivals here. I kept the scale the same for comparison purposes.

excess phase of an unsmoothed measurement



excess phase of a measurement with a 100 cycle (50 left, 50 right) frequency dependent window applied



excess phase of a measurement with a 30 cycle (15 left, 15 right) frequency dependent window applied



obviously as we "close" (reduce length of) the window then we exclude more and more data which serves to quieten down the excess phase view, therefore you have to ask what size window should you choose for this purpose?
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post #13661 of 13662 Unread Today, 04:35 PM
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Originally Posted by Alan P View Post
Are you saying the measurements I've taken with the mic set to 80 are invalid somehow? If so, that sux.
as far as I recall, REW is aware of this and adjusts accordingly so the levels remain accurate. You may want to search, or ask directly, on HTS to confirm that (but it would be a strange thing if REW didn't handle this properly).
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post #13662 of 13662 Unread Today, 04:57 PM
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Quote:
Originally Posted by Alan P View Post
Sorry if I gave wrong advice, it was just the advice I was given (not here, in the ULF thread). I couldn't measure over ~118db with the mic at 100, I turned it down to 80 and now I can measure to ~135db (and yes, I realize most folks have no need to measure that high but I was doing max output/compression sweeps on my T-18s).

Are you saying the measurements I've taken with the mic set to 80 are invalid somehow? If so, that sux.
I am not saying the measurements are invalid. For your own satisfaction, you should measure REW output with an external SPL meter to understand the relationship between the Windows sensitivity setting and REW. A little detective work will set you at ease.

So, I apologize, perhaps "wrong advice" was too strong a statement. I just think we should understand why Matt is having his issue when it should be functioning exactly like my setup.
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