Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 49

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Originally Posted by AustinJerry 

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Originally Posted by kbarnes701 

Quote: Originally Posted by AustinJerry 

Taking Pre-Out measurements with REW

 

 

Jerry - great work - thanks. Should this form a chapter in the Guide (in the 'more advanced' section)?

 

If you think so, then yes.  Cut and paste is quite easy.

It  would be a pity for it to be submerged in the thread as time passes I think. You could make a section for more advanced use and include it in there, along with anything else that might crop up over time. Just a thought.

Rev 2.4 of the REW Guide has been posted.

Changes in this revision:

• Removed REW Soundcard Calibration section (left a placeholder) because it is no longer required
• Made minor revisions to the ETC section
• Added section describing the Pre-out measurement procedure

The guide can be downloaded at the link in my signature.

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Originally Posted by amirm 

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Originally Posted by AustinJerry 

Audyssey off:

That shows the typical high pass filter on laptop mic. If you turn that into a calibration file for REW, it will then show up as a flat straight line. Once there then the Audyssey correction will show properly rather than falling that confusing curve which does not exist in real life:
 

So that's what that is, Amir.  I didn't have that problem using the EMM-6 with it's calibration file:

Unfortunately, I'm not sure I know how to generate a microphone calibration file from a measurement curve.  Care to provide some direction?

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Originally Posted by amirm 

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Originally Posted by AustinJerry 

Unfortunately, I'm not sure I know how to generate a microphone calibration file from a measurement curve.  Care to provide some direction?

Sure. Instead of measuring the pre-amp as you do normally, use the "Calibrate..." button in the Preferences pane. Keep hitting Next as it instructs you and REW will do the rest. Once there, measure again as you did and this time it should be ruler flat without EQ.

Perfect, I'll try that tomorrow.  If successful, I'll update the procedure.  Thanks.

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Originally Posted by Pres2play 

Hi, Jerry (and team). REW virgin here. I'm half-way through this thread and hoped I'd be finished before my UMM-6 Mic arrived, but it's here now and I have a few question which may have been answered recently, so please bare with me.

1. When I do the REW microphone calibration with my RS SPL meter, I get a warning about "input sensitivety." How/where do I adjust this?

2. I'm going HDMI from my laptop to my Oppo BDP-105 which, AFAIK, only has Absolute Volume, not Relative. How important is it to use relative with REW? I'll post this in the Oppo thread, of course, in the meantime.

BTW, I'm so excited you guys started this thread. I've always wanted to toy with REW but was too put off by the setup requirements. When someone mentioned the USB mic and recommended this thread, I immediately started to read from post 1. Then when I saw your guide and learned of the HDMI hookup I knew I had to get involved. Can't wait to finally do some cals!

I am unfamiliar with the "input sensitivity" warning.  Can you post a screen print so we can look at it?

Why is the Oppo in the loop?  The HDMI cable from the laptop should be connected to the AVR.  Please explain what you are trying to do.

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Originally Posted by Pres2play 

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Originally Posted by AustinJerry 

I am unfamiliar with the "input sensitivity" warning.  Can you post a screen print so we can look at it?

Why is the Oppo in the loop?  The HDMI cable from the laptop should be connected to the AVR.  Please explain what you are trying to do.

I'll post a screen shot if can remember how. But at the end of the warning, the "mic/meter" window said I had 170 dB head room which can't be right.

I'm not using a receiver; the Oppo is a Blu-ray player AND prepro. It's connected directly to the power amps via 5.1 analog.

Yes, something is clearly wrong if you get 170db headroom.  If the test tone is registering 80dB on your SPL, the output loop is working properly.  It sounds like to me that the signal from the microphone is too low.  Did you adjust the mic input in Windows Audio to be 100%?  When the test tone is playing, you should see a signal registering on the REW SPL meter.  Are you seeing a signal?

Ah, an analog purist!  Nothing wrong with that.  I'll bet your system sounds great.  Unfortunately, even though I have an Oppo myself, I have no experience using it as a prepro.  

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Originally Posted by AustinJerry 

Quote:

Originally Posted by amirm 

Quote:

Originally Posted by AustinJerry 

Unfortunately, I'm not sure I know how to generate a microphone calibration file from a measurement curve.  Care to provide some direction?

Sure. Instead of measuring the pre-amp as you do normally, use the "Calibrate..." button in the Preferences pane. Keep hitting Next as it instructs you and REW will do the rest. Once there, measure again as you did and this time it should be ruler flat without EQ.

 

Perfect, I'll try that tomorrow.  If successful, I'll update the procedure.  Thanks.

Jerry, your enthusiasm and your energies in this regard are boundless. I am sure I speak for everyone when I say 'thank you' for all the effort you put in.

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Originally Posted by Pres2play 


2. I'm going HDMI from my laptop to my Oppo BDP-105 which, AFAIK, only has Absolute Volume, not Relative. How important is it to use relative with REW? I'll post this in the Oppo thread, of course, in the meantime.
 

Absolute and Relative volumes are just two ways of looking at the same thing. It won’t make any difference to REW - so long as you can get the appropriate level (eg 80dB) you are good to go, regardless of whether this would be -14dB on a relative MVC or 56 or whatever on an absolute scale.

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Originally Posted by jkasanic 

 

Audyssey Sub Distance Tweak Procedure.pdf 986k .pdf file

 

HSAOT, you did remind me about the sub distance tweak either here or in the Audyssey thread.  I haven't done anything with it yet for the aforementioned reasons.  If the timing of all of this doesn't improve then I'm thinking of doing another round of measurements trying to improve the current location as I'm tired of watching movies with substandard sound quality! 

It is well worth doing the sub distance tweak - it is easy to do and doesn't take all that long but it can make a tremendous difference. See Jerry's graphs in that little Guide I complied for an example of the difference it can make.

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Originally Posted by Pres2play 

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Originally Posted by AustinJerry 

Yes, something is clearly wrong if you get 170db headroom.  If the test tone is registering 80dB on your SPL, the output loop is working properly.  It sounds like to me that the signal from the microphone is too low.  Did you adjust the mic input in Windows Audio to be 100%?  When the test tone is playing, you should see a signal registering on the REW SPL meter.  Are you seeing a signal?

Ah, an analog purist!  Nothing wrong with that.  I'll bet your system sounds great.  Unfortunately, even though I have an Oppo myself, I have no experience using it as a prepro.  

Here's the screen shot. I checked Sound>Recordings>UMM-6>Properties>Level, but level reads:100. What am I missing?

The Oppo is fantastic in analog mode but there are problems with the room and I think it might be severe. I'll post some graphs soon, if I can get this little problem with the mic figured out.

On the REW SPL that you show in the screen shot, while the test tone is playing, you should be able to drag the "SPL Reading Calibration" window out of the way and look at the level meter being displayed, as in the screen shot below.  The microphone signal should be clearly registering somewhere on the scale, which is from -100dB to 0dB, and the bar should be in the green range.  What do you see?

If no sound is registering in the SPL meter, then exit REW and try the Windows Sound Recorder test described on page 25 of the Guide.  The Sound Recorder should show a level as you are talking into the mic, and when you save the file, you should be able to clearly hear your voice in the recording.

If the mic fails both of these tests, you may have a defective mic.

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Originally Posted by JChin 

Hi Jerry, got the mic last week and downloaded cal files from the USB stick. The sheet of paper that came with the mic say to download cal file in text format from Dayton website. Do I need to download this text format as well? I didn't see it mention in the v2.4 REW Guide.

Glad you received the mic.  The only calibration files you need are on the USB stick.  Make sure you use the one for a 90-degree mic orientation.

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Originally Posted by Pres2play 

 

The mic doesn't work with Sound Recorder either. It's enabled in the sound control panel and level is set at 100, but no good. I called Cross Spectrum Lab and Herb (?) said he would check if there were any compatibility issues with Windows7.
 

I am using the UMM-6 with Windows 7 without any problems.  Is the blue LED on the mic body lit when you have it plugged into the USB port?  Have you tried it on a different USB port?

Same here.  Win7 is not the issue.

Yes, unfortunately it sounds like you have a bad mic.  The only other thing you might try is plugging it into a different computer, perhaps a friend's, or one at work?  This would rule out the laptop as being the issue.

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Originally Posted by AustinJerry 

Yes, unfortunately it sounds like you have a bad mic.  The only other thing you might try is plugging it into a different computer, perhaps a friend's, or one at work?  This would rule out the laptop as being the issue.

It\s odd that the mic is defective though. I can believe this with an out-of-the-box product, but Herb has calibrated this mic and it must have worked when he did that surely?  HST I can't think of anything else to suggest. If Windows and REW can both 'see it', then it ought to, well, just work.