Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 415 - AVS Forum
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post #12421 of 12831 Old 12-02-2014, 05:28 PM
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Quote:
Originally Posted by mlah384 View Post
See red remarks...

I keep getting message about clipping...

Do I need an external SPL meter to calibrate REW??

What volume do i set my Denon 4520 avr to?
What do I set gains on inuke 6000dsp to? leave them as is?

Do you have any links to REW tutorials that use HDMI, AVR, etc?

Thanks!
All your questions are answered in the Guide. Have you read through the Guide yet?
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post #12422 of 12831 Old 12-02-2014, 05:32 PM
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I uninstalled REW and started from scratch. ASIO is now showing in REW but now the HDMI is not available in REW! I can't figure out why... i've gone over all the steps in the pdf a dozen times... not sure what the problem is... The HDMI was available in REW earlier, but ASIO wasn't... now it's the reverse.

Under the "Output" field, i have two choices:
1. Not Connected 1
2. Not Connected 2

Also there is no small play icon next to HDMI in ASIO window...

But, the HDMI is working. I'm currently on the laptop connected to the AVR via HDMI typing this message... sound works through AVR, etc... Any thoughts? Is my laptop just too outdated?

Last edited by mlah384; 12-02-2014 at 05:49 PM.
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post #12423 of 12831 Old 12-02-2014, 05:43 PM
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Welcome to the long list of REW users who have issues with ASIO, which is beta software with limited support. Reboot the laptop, and give it another try.
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post #12424 of 12831 Old 12-02-2014, 05:50 PM
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Quote:
Originally Posted by mlah384 View Post
Thanks for the link!

ASIO is not available in REW... my laptop is a Dell M1530, might be too old?
That will be problematic, since ASIO4ALL v2 is needed for the HDMI /UMIK-1 / Laptop REW set up, room correction measurement and analysis. My laptop is circa 2011, my HMDI spec is 1.4b, with AMD High Definition Audio support. So, perhaps, your HDMI audio out spec may not accept ASIO4ALL v2 seems like it should, not sure why you're having issues with REW not picking up the ASIO4ALL driver.


Check out this link below...may help?


https://www.image-line.com/support/F...s_asio4all.htm

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post #12425 of 12831 Old 12-02-2014, 06:01 PM
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Quote:
Originally Posted by AustinJerry View Post
Just curious, Randall, why post instructions that are already outlined in the REW Guide. Are you familiar with that document?
I think the post was something like "what is the quickest way to get REW set up via HDMI / UMIK-1 (a usb mic) & a laptop". Since I had just completed my own set up, I thought it might be helpful to others as a quick start, cut to the chase "cheat sheet" hardware wise. I'm not promoting any particular retailer or usb mic, it's just what I did to get REW up and running hardware wise, but I also, do not intend to mislead anyone as well. As I pointed out in my post, there is a plethora of AVS posts regarding "how to use REW" once the hardware is set up and of course, there's the REW guide, which I highly recommend as required reading to get the most out of your hardware set up.

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post #12426 of 12831 Old 12-02-2014, 06:05 PM
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The Guide represents a collaboration of a number of contributors on this thread, and I just want to make sure that people seeking advice here get consistent recommendations. That is why I asked whether you are familiar with the guide or not.
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post #12427 of 12831 Old 12-02-2014, 06:35 PM
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i uninstalled everything (REW and ASIO) then restarted the computer. I installed REW then ASIO .. i then restarted the computer again... I started up REW, it detected mic and asked for cal file. Now I can't get either the HDMI nor the mic to appear! This is very frustrating. Is the laptop just too old?
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post #12428 of 12831 Old 12-02-2014, 07:15 PM
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Quote:
Originally Posted by mlah384 View Post
i uninstalled everything (REW and ASIO) then restarted the computer. I installed REW then ASIO .. i then restarted the computer again... I started up REW, it detected mic and asked for cal file. Now I can't get either the HDMI nor the mic to appear! This is very frustrating. Is the laptop just too old?

Maybe, your laptop is circa 2007 (per Dell), the ASIO4ALL driver and control panel is there which is correct, however, the Output should be "HDMI output 0" or something like that, and the Input should be UMIK-1.


If you have an opportunity to use another laptop that's newer, then I'd try that, at least it will confirm that your laptop may not have the specs needed. I don't know nor have I read anywhere what the minimum hardware and/or software requirements (spec wise) for ASIO4ALL v2 to run within REW.


My Win7 laptop is about three years old, I was pleasantly surprised that I was able to set up REW (HDMI/USB MIC/LAPTOP) fairly easily, meaning, I had no issues whatsoever with REW, the ASIO4ALL driver, the USB MIC in, the HDMI audio out and the AVR HDMI in. It all worked flawlessly, the first time. It's a very slick and straight forward set up, there is no need to use or calibrate an external soundcard or DSP or the need to calibrate an internal soundcard. Your laptop screen shows up on your HDTV or projector via your AVR and it's very quick to set up, it's pretty much "plug-n-play". But, once you're set up, using REW and interpreting the results, I'll defer to the REW Guide, as well as to the very helpful AVS posts.

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post #12429 of 12831 Old 12-02-2014, 08:32 PM
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Quote:
Originally Posted by 3ll3d00d View Post
Yes you would normally prioritise the centre.
Quote:
Originally Posted by Alan P View Post
Yes, if you are 100% movies, the center is the most important.
The only way to improve on the splice with your mains is to move them. Is that possible in your situation? If not, then I say find the distance setting that favors the CC but doesn't make the mains suffer too much.
Unfortunately, I can't move the speakers due to space restriction (blocked by sofa and side cabinet).
Anyway, I'll optimize my center. Gunshots sound better when the center speaker is properly xo at the 50-90Hz region, which is critical in mid bass slam.
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post #12430 of 12831 Old 12-02-2014, 08:35 PM
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Quote:
Originally Posted by mlah384 View Post
i uninstalled everything (REW and ASIO) then restarted the computer. I installed REW then ASIO .. i then restarted the computer again... I started up REW, it detected mic and asked for cal file. Now I can't get either the HDMI nor the mic to appear! This is very frustrating. Is the laptop just too old?

Same here and my laptop is only three years old. I just use Java w/hdmi and umm6 mic instead and it works great.


Sent using Tapatalk since the mobile version is still
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post #12431 of 12831 Old 12-03-2014, 08:15 AM
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Quote:
Originally Posted by mlah384 View Post
i uninstalled everything (REW and ASIO) then restarted the computer. I installed REW then ASIO .. i then restarted the computer again... I started up REW, it detected mic and asked for cal file. Now I can't get either the HDMI nor the mic to appear! This is very frustrating. Is the laptop just too old?
Probably something you already know, but make sure you have the mic and HDMI plugged in before starting REW. I've found that if I don't have everything hooked up prior to launching REW it can sometimes not detect the mic and/or HDMI.

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post #12432 of 12831 Old 12-03-2014, 11:07 AM
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Quote:
Originally Posted by ambesolman View Post
Same here and my laptop is only three years old. I just use Java w/hdmi and umm6 mic instead and it works great.


Sent using Tapatalk since the mobile version is still
@mlah384 :

I agree. No need for ASIO issues to prevent you from proceeding using the Java driver. The instructions are in the guide. You can be completely function WRT taking the measurements that are useful.
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post #12433 of 12831 Old 12-03-2014, 11:36 AM
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Out of curiosity, what rise time and window are you guys using on the decay graphs?

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post #12434 of 12831 Old 12-03-2014, 02:01 PM
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Originally Posted by jim19611961 View Post
Out of curiosity, what rise time and window are you guys using on the decay graphs?
I've always left them at the defaults for 2 reasons; it is not a view I've spent much time on & I've only ever looked at the sub so you need a longer window to get the frequency resolution to see anything.

It would be interesting to know why using a shorter left window (rise time) has the effect, at least in my measurements, of hastening the decay though. I don't understand why it has that effect (probably a Q for HTS).
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post #12435 of 12831 Old 12-03-2014, 02:24 PM
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Originally Posted by jim19611961 View Post
Out of curiosity, what rise time and window are you guys using on the decay graphs?
I always vary them depending on the nature of the measurement and what I want to look at. Generally I like to keep the rise time as short as possible to reduce time smear.

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post #12436 of 12831 Old 12-03-2014, 02:53 PM
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Originally Posted by 3ll3d00d View Post
I've always left them at the defaults for 2 reasons; it is not a view I've spent much time on & I've only ever looked at the sub so you need a longer window to get the frequency resolution to see anything.

It would be interesting to know why using a shorter left window (rise time) has the effect, at least in my measurements, of hastening the decay though. I don't understand why it has that effect (probably a Q for HTS).
This is my point in asking. Consequently, you get a very different measure (short vs long rise times).

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post #12437 of 12831 Old 12-03-2014, 02:58 PM
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Originally Posted by markus767 View Post
I always vary them depending on the nature of the measurement and what I want to look at. Generally I like to keep the rise time as short as possible to reduce time smear.
I assume you mean depending on the frequency area in question? Mainly, people here anyway, are looking in the bass region. In the case of my measurements, the difference in decay at 40hz @ 160ms of a rise time of 1ms vs 100ms is more than a 10db difference.

If we are using -20db at 160ms as a reference, we need to pin down what rise time to use. Otherwise, we are looking at incompatible data when doing comparisons.

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post #12438 of 12831 Old 12-03-2014, 03:25 PM
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Originally Posted by jim19611961 View Post
This is my point in asking. Consequently, you get a very different measure (short vs long rise times).
FWIW I posted that Q earlier tonight http://www.hometheatershack.com/foru...ter-decay.html so hopefully JohnM will be along to give some insight at some point.
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post #12439 of 12831 Old 12-03-2014, 04:24 PM
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Originally Posted by jim19611961 View Post
I assume you mean depending on the frequency area in question? Mainly, people here anyway, are looking in the bass region. In the case of my measurements, the difference in decay at 40hz @ 160ms of a rise time of 1ms vs 100ms is more than a 10db difference.

If we are using -20db at 160ms as a reference, we need to pin down what rise time to use. Otherwise, we are looking at incompatible data when doing comparisons.
John suggested rereading the waterfall help page & I think this explains it quite clearly. Basically the left window & the slice interval control how quickly you move past the initial impulse (of the direct sound) and get into the tail (where you'd expect the level to be lower). It's still the same data though.
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post #12440 of 12831 Old 12-04-2014, 01:19 AM
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Originally Posted by jim19611961 View Post
I assume you mean depending on the frequency area in question? Mainly, people here anyway, are looking in the bass region. In the case of my measurements, the difference in decay at 40hz @ 160ms of a rise time of 1ms vs 100ms is more than a 10db difference.

If we are using -20db at 160ms as a reference, we need to pin down what rise time to use. Otherwise, we are looking at incompatible data when doing comparisons.
We can't escape the tradeoff between time and frequency resolution. You have to understand what that really means. You will never see the real decay that's why you have to adjust the window size and look at the data with different settings so you get an idea what reality might look like.

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post #12441 of 12831 Old 12-04-2014, 07:33 AM
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Originally Posted by jim19611961 View Post
I assume you mean depending on the frequency area in question? Mainly, people here anyway, are looking in the bass region. In the case of my measurements, the difference in decay at 40hz @ 160ms of a rise time of 1ms vs 100ms is more than a 10db difference.

If we are using -20db at 160ms as a reference, we need to pin down what rise time to use. Otherwise, we are looking at incompatible data when doing comparisons.
I don't see much of a change when rise time is reduced from 100ms to 10ms. It is only going below 10ms that changes become significant.

FWIW, the guide recommends leaving the settings at their default values, so when decay graphs are posted here (which is not very often), assuming everyone is using the default values, then comparisons are consistent.

I am not sure I understand Markus' comment that one must vary the rise time to fully comprehend the data. Perhaps an example would make this more clear.
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post #12442 of 12831 Old 12-04-2014, 09:52 AM
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Originally Posted by Ratamacue View Post
If I'm understanding your comment on the 17.4 angle at the MLP => it's based on 1/3 rule (24 / 3 = 8 and 11 / 3 = 44in) which is to get into the ballpark to avoid room modes etc.. Its close I suppose, but with only 11ft, there isn't a lot space width wise. By design, it leaves room behind and to the sides of the speaker. They aren't buried in the corner or next to a wall / boundaries. As you pointed out, there are many options for placement and I'll try some at the 30deg (closer to side walls) and see how things correlate.

Also, the subs in the current spot offer great integration so far (corner loading/reinforcement). I can't tell where they are. If I move them closer to the back of the mains (say 1ft behind), they seem to be in a null and don't produce much low end at all.

Attached is my layout, thanks again for your time.
BTW, I don't believe you attached your layout to your post. The missing piece of information is the current placement of your two subs.

Regarding the distance between your mains, I was only presenting information on an accepted placement principle, that is having the MLP, left front, and right front form an equilateral triangle. Your current 44" distance produces the following:



Angle "A" is 17.4 degrees, considerably smaller than the 30 degrees you would have with an equilateral triangle. In the worksheet I have, I can simply vary the distance "a" until the formulas result in a 30 degree angle. This occurs when there is 41x2=82 inches between the mains, leaving 25" from each main to the side wall.



I don't know if this placement would be acceptable to you, or how it would alter the sound, but I think it is worth a try. Clearly, the different spacing between the speakers would alter the width of the soundstage, which I think could be beneficial for two-channel music. Another thing to consider is that the current placement of the mains puts them at the 1/3 point of the room length, as well as the 1/3 and 2/3 points of the width. Moving the mains to where I suggested places them at the 1/5 and 4/5 points of the width, which I suspect will also alter the overall frequency response in the room. Whether this would be an improvement or not, only an experiment will tell.

And finally, while you may not find this recommendation to your liking, I would experiment by setting the mains to small, and crossing over to the subs at a higher point, say 80Hz. Why? Because the smoothness of the bass is all about positioning. With the mains, you have a conflict. Either they are placed to provide the best imaging, or they are placed to provide the smoothest bass. These two objectives can rarely be satisfied by one placement. So, position the mains for best imaging, and position the subs for best bass. I am assuming you have significant latitude WRT sub placement. Anyway, you probably know all this, since I am only repeating conventional wisdom.

WRT your question about the measurement levels and the shape of the waterfalls, if you go back and check, I think you will find that it is the change in the Time Range setting from 600ms to 450ms that produced the biggest change in the appearance of the waterfalls. The guidance that has been given here is to first measure your listening room's noise floor (typically in the 45dB-50dB range), and then measure at a level that gives you 40dB of clearance above the noise floor. Interpreting the resulting waterfalls continues to be one of the more difficult concepts to grasp. You can read the REW help section on waterfalls, but you may come away even more confused. If I recall guidelines we received from John M., he said to focus on the first 20dB from the top of the graph. Look for uniformity in the time slice waves in the first 20dB. Closely-spaced waves producing deep "ridges" are an indication of trouble at that particular frequency.

So, in your waterfalls, I would pay attention to the marked areas:



I don't recall seeing frequency response graphs of the mains+subs. My recommendation would be:

- Experiment with the equilateral triangle placement of the mains, focusing on imaging improvements.
- Set the mains to small with an 80Hz crossover.
- Measure bass response, first with subs alone, then with subs+mains.
- Experiment with sub placement to optimize bass frequency response.
- Once frequency response is optimized, look at the waterfalls/spectrograms. if bass ringing above 30Hz is not as good as you want it to be, consider adding room treatments.
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post #12443 of 12831 Old 12-04-2014, 10:02 AM
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I don't see much of a change when rise time is reduced from 100ms to 10ms. It is only going below 10ms that changes become significant.

FWIW, the guide recommends leaving the settings at their default values, so when decay graphs are posted here (which is not very often), assuming everyone is using the default values, then comparisons are consistent.

I am not sure I understand Markus' comment that one must vary the rise time to fully comprehend the data. Perhaps an example would make this more clear.
This maybe the case in your scenario, but not mine.

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post #12444 of 12831 Old 12-04-2014, 10:04 AM
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This maybe the case in your scenario, but not mine.
Interesting. Wonder why our two scenarios are so different?
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post #12445 of 12831 Old 12-04-2014, 10:13 AM
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Interesting. Wonder why our two scenarios are so different?
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Just a guess, but maybe group delay is playing a role here. More than a coincidence that my delay curve looks a lot like my decay curve?

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post #12446 of 12831 Old 12-04-2014, 10:18 AM
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Originally Posted by markus767 View Post
We can't escape the tradeoff between time and frequency resolution. You have to understand what that really means. You will never see the real decay that's why you have to adjust the window size and look at the data with different settings so you get an idea what reality might look like.
Good reminder. But isnt there an optimum time reference when the frequency is known?

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post #12447 of 12831 Old 12-04-2014, 10:59 AM
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Originally Posted by AustinJerry View Post
Interesting. Wonder why our two scenarios are so different?
probably because the shape of your IR is different. I made a quick gif to show what the decay or waterfall is doing, watch out how the windowed IR gets "smaller" on the left hand side as the window slides forward. The decay trace is then the frequency view of that cut down IR so it is showing the spectral content of what was in the impulse in that time window. This might show why changing the window settings can radically change the way the decay looks because you are simply reporting on a different view on the IR each time.



If we zoom out so you can see the window itself move



The other 2 attachments show the decay view vs a simple FR view (when you move the window over manually, just to confirm this is what it is doing)
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post #12448 of 12831 Old 12-04-2014, 11:18 AM
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Could a few of you post your GD also showing Excessive GD like I did in post 12448 just so I have a reference to my own measurements?

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post #12449 of 12831 Old 12-04-2014, 11:39 AM
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post #12450 of 12831 Old 12-04-2014, 11:43 AM
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