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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 171

post #5101 of 9620
Here we go!

Gear mentioned in this thread:

post #5102 of 9620
Quote:
Originally Posted by jlpowell84 View Post

Here we go!
Nice!! My wife came downstairs and saw my setup for the first time and said "what the hell is that?" I said my meauring equipment. She said "man your a nerd" lol
post #5103 of 9620
Ok, so do I need to do the calibration with the spl meter if I loaded the mic cal file from cross spectrum awhile ago? I'm not getting any response from the mic so something is up

For example, I tried the noise floor part of Jerry's begginer guide and I get no response
post #5104 of 9620
I don't know what "a while ago" means. If there is any doubt, re-run the mic calibration. I only takes a few seconds. Then see if things are working.
post #5105 of 9620
Well I know what awhile ago means in my mind! Lol.

Ok so yea the mic cal file is still there, loaded about 3 months ago. I just calibrated the spl meter correctly and now the REW spl meter is the same as my hand held

Have me a max of 105

I had to use the speaker because at 80 the Submersives would have been really loud.
post #5106 of 9620
I'm not getting the RTA to display the noise floor measurement though when I hit the red button

I set from 15-20000 just like the guide says, then hit the red/record looking button
post #5107 of 9620
Oh snap! Wow! Sorry truly! Needed to go lower on the graph! It's there!
post #5108 of 9620
Here it is, I will have to do iPhone shots as my internet won't be hooked up till Tuesday.
post #5109 of 9620
That looks typical. Internet connection would be nice.

BTW, having a calibration file loaded in the Preferences page is different from "calibrating the mic". The latter means configuring REW to associate an electrical signal coming from the mic with an external source of known sound pressure. Without calibrating, REW cannot interpret what the mic is measuring.

The calibration file simply allows REW to compensate the measurements it receives from your mic against a known reference mic to ensure you are receiving accurate measurements.
post #5110 of 9620
Ok here is 3 measurements. I decided to save to desktop and upload on my iPhone so we could have snapshots and not iPhone photos. First is 15-20k, second is 5-200, and third is 5-200 waterfall. It's pretty exciting to be honest to be up and running. Now the fun begins with all sorts of EQ. Manual and electronic.


post #5111 of 9620
Nice first effort. Comments on presentation:

- lower limit on frequency sweeps should be 15Hz.
- For the full-range frequency sweep, use 1/6 smoothing to make it easier to read, and lower the upper limit to 20,000Hz.
- The bass frequency doesn't look bad, but there could be some improvement. The sharp dip might be correctable by adjusting sub distances.
- Hard to comment on the waterfall graph. The window is set to 300ms, which doesn't allow us to see when the resonances disappear into the noise floor. Increase the time window to 450, or even 600ms, to see if we can see where the resonances stop.
- The waterfall doesn't seem to be generated from the same measurement as the bass frequency sweep above it. The top of the waterfall curve should match the bass frequency curve if they are indeed the same measurements. Are they?

Edit: You should also be consistent from graph to graph with the vertical axis. I recommend using 50-100dB as the vertical axis, and 15-20,000Hz as the horizontal axis for a full sweep, and 15-300Hz for a bass sweep.
post #5112 of 9620
Ok, thanks Jerry, I will do those things. Yes I did generate the waterfall from the same bass sweep. I took a screen shot of your instructions to do. I am really hoping the sub placement is going to work out as I like them there. One on either side of the tv stand.
post #5113 of 9620
Quote:
Originally Posted by jlpowell84 View Post

Ok, thanks Jerry, I will do those things. Yes I did generate the waterfall from the same bass sweep. I took a screen shot of your instructions to do. I am really hoping the sub placement is going to work out as I like them there. One on either side of the tv stand.

 

The waterfall is still suspect.  Do you see what I mean when I say the top edge of the waterfall graph should look exactly like the frequency sweep graph above it?

 

Edit:  Here is an example:

 

 

 

Not that the top of the waterfall looks the same as the graph above it.


Edited by AustinJerry - 10/10/13 at 9:48pm
post #5114 of 9620
Yes I totally understand. I must have done something wrong. I will do a little more this weekend smile.gif. One question though, what about measuring below 15hz? I know it's a frequency that doesn't have much but part of me wants to know what is down there when I measure. Is 15 hz the standard simply to start from?
This weekend I want to run audyssey to see what it does to the subs. I may even try some different placements to have fun.
Edited by jlpowell84 - 10/10/13 at 11:10pm
post #5115 of 9620
Quote:
Originally Posted by Brian Fineberg View Post

Nice!! My wife came downstairs and saw my setup for the first time and said "what the hell is that?" I said my meauring equipment. She said "man your a nerd" lol

My fiancé and I call my hobby "nerding out". If I'm on the forums I just say I'm nerding out. And tonight I sent her a pic of my first nerd graph smile.gif
post #5116 of 9620
Quote:
Originally Posted by AustinJerry View Post

- The waterfall doesn't seem to be generated from the same measurement as the bass frequency sweep above it. The top of the waterfall curve should match the bass frequency curve if they are indeed the same measurements. Are they?

The curves do match. It's just that the y-axis and perspective on the waterfall don't match.
post #5117 of 9620
Quote:
Originally Posted by markus767 View Post

The curves do match. It's just that the y-axis and perspective on the waterfall don't match.

Oh da! One went to 5 and the other 15.
post #5118 of 9620
^
That too but I was talking about the y-axis. One graph shows about 80dB whereas the other shows 60dB.
post #5119 of 9620
Quote:
Originally Posted by jlpowell84 View Post

Yes I totally understand. I must have done something wrong. I will do a little more this weekend smile.gif. One question though, what about measuring below 15hz? I know it's a frequency that doesn't have much but part of me wants to know what is down there when I measure. Is 15 hz the standard simply to start from?
This weekend I want to run audyssey to see what it does to the subs. I may even try some different placements to have fun.

Nothing wrong with measuring below 15Hz. Keith does it all the time just to make the rest of us feel bad. wink.gif
post #5120 of 9620
wink.gif
Quote:
Originally Posted by markus767 View Post

^
That too but I was talking about the y-axis. One graph shows about 80dB whereas the other shows 60dB.

You are correct--I should have noticed that. It demonstrates the importance of consistency when presenting measurements.
post #5121 of 9620
Quote:
Originally Posted by AustinJerry View Post

Nothing wrong with measuring below 15Hz. Keith does it all the time just to make the rest of us feel bad. wink.gif

Ok cool, just wanted to make sure it wasn't a technical reason. I will be sure to give attention to graph presentation and give Audyssey a go this weekend and see what it does with my room.
post #5122 of 9620
Can you put a sub next to a large solid speaker such that there is just barely a straight line of sight to the MLP.
One sub is only 12" from wall whereas speaker is 24" from wall and the speaker kind of hides the sub when seated at MLP.
The speaker is wood - very solid - so i was just wondering if its best to keep subs away from solid objects or it doesn't really matter?
Will the same room modes occur not matter what solid objects are next to the sub?

thanks
post #5123 of 9620
Quote:
Originally Posted by Brian Fineberg View Post
 
Nice!! My wife came downstairs and saw my setup for the first time and said "what the hell is that?" I said my meauring equipment. She said "man your a nerd" lol

 

Hahaha.  Mrs Keith asks questions like that. When I reply she just rolls her eyes...

post #5124 of 9620
Quote:
Originally Posted by jlpowell84 View Post

Ok here is 3 measurements. I decided to save to desktop and upload on my iPhone so we could have snapshots and not iPhone photos. First is 15-20k, second is 5-200, and third is 5-200 waterfall. It's pretty exciting to be honest to be up and running. Now the fun begins with all sorts of EQ. Manual and electronic.


 

Did you remember to turn DEQ off?  Are these with Audyssey on or off?

 

As Jerry says, it is important to be consistent with the parameters because otherwise any comparisons are difficult. Try annotating the graphs when you save them - eg, Aud ON, DEQ Off, 1/6th smoothing, Subs + R + L etc.

post #5125 of 9620
Quote:
Originally Posted by AustinJerry View Post


- The waterfall doesn't seem to be generated from the same measurement as the bass frequency sweep above it. The top of the waterfall curve should match the bass frequency curve if they are indeed the same measurements. Are they?

 

One starts at 5Hz and one at 15Hz... that confuses the picture somewhat.

 

I bet the ringing will look really bad even at 450ms or 600ms.

post #5126 of 9620
Quote:
Originally Posted by jlpowell84 View Post

Ok, thanks Jerry, I will do those things. Yes I did generate the waterfall from the same bass sweep. I took a screen shot of your instructions to do. I am really hoping the sub placement is going to work out as I like them there. One on either side of the tv stand.

 

It's confusing because you're not consistent with the parameters - one is from 5Hz and the other from 15Hz.  Use the conventions in Jerry's guide. The waterfall is a good example of how failing to standardise the parameters creates confusion.  Not having a pop at you - it's all very confusing at first and you are doing good!

post #5127 of 9620

Not jlpowell84 but I believe these measurements are pre-Audyssey.  I can't emphasize enough the importance of the annotations!

post #5128 of 9620
Quote:
Originally Posted by AustinJerry View Post
 
Quote:
Originally Posted by jlpowell84 View Post

Yes I totally understand. I must have done something wrong. I will do a little more this weekend smile.gif. One question though, what about measuring below 15hz? I know it's a frequency that doesn't have much but part of me wants to know what is down there when I measure. Is 15 hz the standard simply to start from?
This weekend I want to run audyssey to see what it does to the subs. I may even try some different placements to have fun.

Nothing wrong with measuring below 15Hz. Keith does it all the time just to make the rest of us feel bad. wink.gif

 

LOL!!!  

post #5129 of 9620
Quote:
Originally Posted by jlpowell84 View Post
 
Quote:
Originally Posted by Brian Fineberg View Post

Nice!! My wife came downstairs and saw my setup for the first time and said "what the hell is that?" I said my meauring equipment. She said "man your a nerd" lol

My fiancé and I call my hobby "nerding out". If I'm on the forums I just say I'm nerding out. And tonight I sent her a pic of my first nerd graph smile.gif

 

Gee - you know how to treat a lady!  LOL!!  (One day you will be 'misunderstood' for calling your fiancée your fiancé LOL.) 

post #5130 of 9620
Hi all

If I get one of the USB mics mentioned in the help guide, do I need to get a radio shack SPL meter also? Or is the USB mic, mic boom stand, REW software and HDMI cable all I need to start taking measurements?

Thanks
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