Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 358 - AVS Forum
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post #10711 of 11274 Old 07-02-2014, 02:37 PM
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This is covered in the Guide, Alan. Simply choose the second output from the Timing Reference Output drop-down:

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post #10712 of 11274 Old 07-02-2014, 02:52 PM
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Well, cr*p....I looked in the Guide twice today and didn't see that.

Thanks Jerry....and sorry for being a pain!
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post #10713 of 11274 Old 07-02-2014, 02:59 PM
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OK, I just looked through the entire Guide again, twice, and did not see that anywhere! Did it maybe get removed for some reason? I'm looking at version 3.5 of the Guide.
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post #10714 of 11274 Old 07-02-2014, 03:08 PM
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Yes, you are correct. I guess those of us who have been using REW for a long time simply know how to configure the second channel, and we forget what might not be obvious for the first-time user. I'll make a note to add this instruction to a future version of the document. Sorry for the confusion.
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post #10715 of 11274 Old 07-04-2014, 09:09 AM
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I am unable to get the "output" in the preferences section to show HDMI. It only has options for "Not connected 1 and Not connected 2" .

My multi channel HDMI hookup to my processor works fine. I can get all 7 channels plus sub to independently play in the windows sound control panel. My Umm6 mic shows up fine in REW as well.
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post #10716 of 11274 Old 07-04-2014, 09:14 AM
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Quote:
Originally Posted by hifiaudio2 View Post
I am unable to get the "output" in the preferences section to show HDMI. It only has options for "Not connected 1 and Not connected 2" .
Something else has control of the soundcard. Close down the internet browser, and any other obvious programs that may be hooking to the soundcard. Once REW has control with ASIO, it keeps control.
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post #10717 of 11274 Old 07-05-2014, 08:23 AM
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On the topic of soundstage, I found this thread concerning making your speakers disappear. Some nice tidbits.

http://www.hifivision.com/speakers/2...disappear.html

Another:

http://www.stereophile.com/content/w...have-disappear

General Acoustics, but still interesting:

http://www.acousticsciences.com/arti...-in-the-desert

My Room
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post #10718 of 11274 Old 07-05-2014, 10:06 AM
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Although The Register is mostly concerned with information technology issues, bizarrely it published this interesting article on speaker design and measurement.

TL/DR summary. Ignoring audiophile voodoo, DSP is the way to go and if the speaker can't reproduce square waves cleanly then it's garbage.

The part on impulse response was most interesting. That's on page 3. Before that it's a summary of relevant research.
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post #10719 of 11274 Old 07-06-2014, 01:29 AM
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Been working on time aligning my speakers. Here are some graphs showing proper tweeter alignment, with 0.4ms to far and to close.

Take note of the scale of the graph.








These graphs need some smoothing to produce useful results. Here is an unsmoothed graph.


Useless.


Here is the FR around the Xover point.


I have the tweeters a few dB down, as I roll off my final FR from 1khz, to be 6.5dB down at 20khz anyway. My current setup uses pre-amp volume control, so I reduce the noise floor by having the tweeter amp a few dB down also.

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post #10720 of 11274 Old 07-06-2014, 06:14 AM
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Quote:
Originally Posted by jim19611961 View Post
General Acoustics, but still interesting:

http://www.acousticsciences.com/arti...-in-the-desert
Lots of good information on that site. Fantastic paper by Farina (who brought us the swept sine technique):
http://pcfarina.eng.unipr.it/Public/...153-AES110.PDF

Markus

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post #10721 of 11274 Old 07-06-2014, 07:42 AM
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Quote:
Originally Posted by markus767 View Post
Lots of good information on that site. Fantastic paper by Farina (who brought us the swept sine technique):
http://pcfarina.eng.unipr.it/Public/...153-AES110.PDF
Thanks for pointing out that specific paper. This article, in addition to other things, goes into masking, which is a topic I would like to understand better. Much of this article is over my head. Conceptually, I get what masking means in a broad sense I think.

What I get is that the direct response creates a masking effect. This effect is mitigated by the burst length. Is my case, using a Haas Kicker, a 25ms (@-6db) terminator is employed which causes a secondary masking effect. What I dont know, or haven't been able to understand thus far, is how far into the time domain each masking element proceeds into the time domain.

Time Domain Masking.JPG

If I am getting this chart, and its subsequent description, a 5ms tone burst has a masking effect to 66ms to -20db. So if one looks at the curve, presumably any reflection artifact below the curve is masked, and those above it are not.

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Jenzen Next ( http://www.troelsgravesen.dk/Jenzen-NEXT.htm )
...

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post #10722 of 11274 Old 07-06-2014, 11:28 AM
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Directivity probably plays a part in that also.
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post #10723 of 11274 Old 07-07-2014, 01:29 AM
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Quote:
Originally Posted by jim19611961 View Post
Thanks for pointing out that specific paper. This article, in addition to other things, goes into masking, which is a topic I would like to understand better.
Yes a very interesting topic. It is key to audibility of reflections or distortion and why single number measurements are nearly meaningless.

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If I am getting this chart, and its subsequent description, a 5ms tone burst has a masking effect to 66ms to -20db. So if one looks at the curve, presumably any reflection artifact below the curve is masked, and those above it are not.
The graph shows how the ear regains sensitivity AFTER the masking sound has been switched off.

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post #10724 of 11274 Old 07-07-2014, 10:15 AM
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Yes a very interesting topic. It is key to audibility of reflections or distortion and why single number measurements are nearly meaningless.
While the bolded part maybe true, most of us here can only equate improving our listening experience with being able to take a measurement, know what it means, and have that lend itself to implementing some change in our setup.

I find the theory fascinating. But if I cant translate that into something I can measure, I am not sure it does me much good.

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Goldpoint Passive
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...

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post #10725 of 11274 Old 07-08-2014, 01:40 AM
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Been working on time aligning my speakers. Here are some graphs showing proper tweeter alignment, with 0.4ms to far and to close.
Not sure what you're doing here. Simply align the impulse responses. But you need a time reference for doing that (loopback on channel 2 in REW).

Markus

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post #10726 of 11274 Old 07-08-2014, 05:24 AM
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Not sure what you're doing here. Simply align the impulse responses. But you need a time reference for doing that (loopback on channel 2 in REW).
I was playing with different active crossovers, so I wanted to see what effect they were having in the time domain. But yes, for midrange/tweeter, the impulse response is the easiest way to time align.
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post #10727 of 11274 Old 07-08-2014, 05:50 AM
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^
I don't think the excess phase group delay shows what you were looking for.

Markus

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post #10728 of 11274 Old 07-08-2014, 06:53 AM
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Well apparently it's useful for time aligning subwoofers/mains, since the impulse response becomes unreliable with low frequencies. So I don't see how it would not also have the same use in the higher frequencies?

Certainly, if I keep all parameters of the measurement the same, and adjust crossover slope/type, adjust the time delay of a singular speaker, I see differences that fit within my expectations of the results.

If you know of a better way, I would love to hear it.

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post #10729 of 11274 Old 07-08-2014, 07:02 AM
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The IR is not unreliable at low frequencies per se but comparing (aligning) a LF IR to a HF IR is tricky. For HF, just looking at the IR or phase alignment in the XO range should be sufficient.

There are quite a few threads on this subject on HTS, one recent one is this one
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post #10730 of 11274 Old 07-08-2014, 08:07 AM
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Quote:
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Well apparently it's useful for time aligning subwoofers/mains, since the impulse response becomes unreliable with low frequencies. So I don't see how it would not also have the same use in the higher frequencies?
Sounds like you've read something somewhere - care to share that link?

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Certainly, if I keep all parameters of the measurement the same, and adjust crossover slope/type, adjust the time delay of a singular speaker, I see differences that fit within my expectations of the results.
Just because you see correlation doesn't mean there is a causal correlation.

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If you know of a better way, I would love to hear it.
I've already propose a better solution.

Markus

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post #10731 of 11274 Old 07-08-2014, 03:01 PM
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Sorry if this is basic and covered somewhere but a search did not yield useful results ... REW has an "EQ" button and both my Xilica xp2040 and upcoming Emotiva UMC-200 are listed there. Will REW take the measurements one has made and output suggested EQ parameters for the PEQ in either of those devices? So all I would have to do is enter what it tells me to?
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post #10732 of 11274 Old 07-08-2014, 03:32 PM
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Quote:
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Sorry if this is basic and covered somewhere but a search did not yield useful results ... REW has an "EQ" button and both my Xilica xp2040 and upcoming Emotiva UMC-200 are listed there. Will REW take the measurements one has made and output suggested EQ parameters for the PEQ in either of those devices? So all I would have to do is enter what it tells me to?
It's actually quite simple.

1. Select the response curve you want to equalize (in the example below it is the subwoofer response).
2. Choose your device (MiniDSP in the example).
3. Click on "Set target level".
4. Click "Match response to target" to generate the EQ filters.
5. Click "Send filter settings to equalizer" to create the export file.
6. Load the file into your DSP.

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post #10733 of 11274 Old 07-08-2014, 03:39 PM
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Quote:
Originally Posted by hifiaudio2 View Post
Sorry if this is basic and covered somewhere but a search did not yield useful results ... REW has an "EQ" button and both my Xilica xp2040 and upcoming Emotiva UMC-200 are listed there. Will REW take the measurements one has made and output suggested EQ parameters for the PEQ in either of those devices? So all I would have to do is enter what it tells me to?
The basic procedure is like Jerry posted but you'll have to enter the filter settings manually for the UMC-200. By the way, the UMC-200 isn't upcoming but available for over a year.

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post #10734 of 11274 Old 07-08-2014, 03:42 PM
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The basic procedure is like Jerry posted but you'll have to enter the filter settings manually for the UMC-200. By the way, the UMC-200 isn't upcoming but available for over a year.
Lol sorry I meant upcoming in MY theater.
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post #10735 of 11274 Old 07-08-2014, 03:52 PM
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Lol sorry I meant upcoming in MY theater.
I see. Just be prepared for a steep learning curve. It's not like clicking "match response to target" would produce anything useful without the user providing meaningful measurements and getting the hidden settings right.
If you want to dig deeper then post in the UMC-200 thread and I can provide you with more details on how to set up your system.

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The REW Guide has been updated to version 3.7.

Recent updates include:

3.6 July 2, 2014 - Updated Step 3a.15 with instruction on how to output to two HDMI channels simultaneously.
3.7 July 8, 2014 - Added section “Using REW to Generate EQ Filters”

There is a link to the Guide in my sig.
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post #10737 of 11274 Old 07-08-2014, 04:23 PM
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Quote:
Originally Posted by AustinJerry View Post
The REW Guide has been updated to version 3.7.

Recent updates include:


3.7 July 8, 2014 - Added section “Using REW to Generate EQ Filters”

There is a link to the Guide in my sig.
Now that's prompt service! Thanks!
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post #10738 of 11274 Old 07-09-2014, 02:48 AM
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Quote:
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Sounds like you've read something somewhere - care to share that link?
Can't find the original link I was looking at, and further research shows the usage of GD, not excess GD. Go figure!


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Just because you see correlation doesn't mean there is a causal correlation.
"I see differences that fit within my expectations of the results."

That was my attempt to provoke discussion, especially considering I was making it somewhat obvious it was fitting within my expectations, and wasn't following some industry accepted standard.


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I've already propose a better solution.
I don't expect to be spoon feed, but considering this thread is now at 358 pages, a little hint to the location of this solution would be appreciated.
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post #10739 of 11274 Old 07-09-2014, 02:53 AM
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^
Do measurements with a timing reference on channel 2 and time-align the IRs.

Probably a good starting point for further reading:
http://www.hometheatershack.com/foru...oup-delay.html

Markus

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post #10740 of 11274 Old 07-09-2014, 03:04 AM
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Thanks Markus. Between that and the link 3ll3d00d shared earlier, I have some good reading to do.
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