# Some advise on this graph, please



## janick (Mar 10, 2011)

First let my appoligize for the possible errors. I'm very new but i think i may have inaccurate data becasue the soundcard was not calibated right. I'm trying everything and fiqured i should just go ahead a post results anyways and maybe somebody can tell my that it is not correct. 

Well it looks as though i cant even attached as i get a security token missing error. I've tried two separate files and the other one just says upload file failed :hissyfit:

Any help please. I'm to the point were I'll pay someone. I live in the Phx area :bigsmile:


----------



## EarlK (Jan 1, 2010)

I believe that you need to have posted 5 times before you can upload pics (as attachments ) .

Read *this thread* for a pretty thorough overview in what extra features you obtain after you've made 5 posts ( though the attachments issue isn't mentioned that I can see ). 

<> EarlK


----------



## janick (Mar 10, 2011)

EarlK said:


> I believe that you need to have posted 5 times before you can upload pics (as attachments ) .
> 
> Read *this thread* for a pretty thorough overview in what extra features you obtain after you've made 5 posts ( though the attachments issue isn't mentioned that I can see ).
> 
> <> EarlK


Thanks EarlK. I'll go to different threads and say "hi" :bigsmile:


----------



## JohnM (Apr 11, 2006)

janick said:


> Thanks EarlK. I'll go to different threads and say "hi" :bigsmile:


Please use the Post Padding Thread for that.


----------



## janick (Mar 10, 2011)

I was able to capture a pic. Would somebody mind critiquing my results. I would like to mention that I had issues calibrating my sound card but I hope I got it right. I think you can tell in the pic that i need to do again. Maybe you can tell what i did wrong by the sloping downward line. Thanks in advance for your help


----------



## EarlK (Jan 1, 2010)

Here's your pic ;










- Sorry but that's not a valid soundcard calibration .

- Hmmm, it seems like a sweep from a live microphone curve was combined with the "C" weighting compensation for a SPL meter // & then entered as the soundcard calibration file . 
- That's quite wrong .

- Best to review the  *"Calibrating The Soundcard"* section which is found in the  *Online REW Help File. * and then try again .

- If there are any specific areas of confusion relating to the mentioned steps ( within the linked-to help section ) just ask about them and someone will try to help ( please reference the step # that's giving you difficulty ) .

regards <> EarlK


----------



## janick (Mar 10, 2011)

I'll get it i promise


----------



## janick (Mar 10, 2011)

EarlK said:


> Here's your pic ;
> 
> 
> 
> ...


i'd like to mention i have a bachelor degree but now i'm starting to question that universities authenticity :coocoo: The problem must be in the section "calibrating the soundcard" item 1. I have the radioshack SPL connected to the "line in" in the computer though a Y adapter. Then i have a cord going from the "line in" to the "line out" on the computer, again using another Y adapter (this is the loopback part that i disconnect when done calibrating). Lastly i have the "line out" going the AUX in the receiver.

I checked the "C weighted SPL Meter" in the Mic/Meter tab and also checked the "use loopback..." under the Analysis tab.

Thanks again for the support. I'll get it i promise


----------



## EarlK (Jan 1, 2010)

Hi janick,

- Unplug the RS Meter, it shouldn't be plugged in while you are making a soundcard calibration .
- Just make a loop-back from *left out to left in *( once you determine what's what on those ambiguous "Y" cables ). 

- Uncheck the "C Weighting" compensation / one doesn't engage that compensation until after a successful SC Calibration / after you have plugged the RS meter back in to make a sweep .

- Uncheck the "use loop-back" for timing reference . That is not part of the SC calibration procedure .


<> EarlK


----------



## janick (Mar 10, 2011)

EarlK said:


> Hi janick,
> 
> - Unplug the RS Meter, it shouldn't be plugged in while you are making a soundcard calibration .
> - Just make a loop-back from *left out to left in *( once you determine what's what on those ambiguous "Y" cables ).
> ...


Hi EarlK,

Thanks for the help










Does that look better. Like you said i did not connect to the SLP meter. I also did not connect to the receiver. FYI - My headroom was under 2

EDIT - hmmm pic didn't work. its in the "my photo"

I also did some measurements but the "phase" graph lead me to believe i did not do everything correctly. The one graph has the soundcard and mic/meter graph which look correct so i'm getting closer. Thank you for taking your time to assist me. I really apreciate this.


----------



## EarlK (Jan 1, 2010)

I looked at that photo , you've made some progress but you're not quite there yet .

Your new pic is a good shot of the raw response of the soundcard, * but it is still uncalibrated *.

It appears that you didn't finish going through the final steps in the process to ask the program to make the calibration file .

Keep reading ( my links ) , then try again & post your new results.

I'll pop in tomorrow morning .


<> cheers


----------



## janick (Mar 10, 2011)

EarlK said:


> I looked at that photo , you've made some progress but you're not quite there yet .
> 
> Your new pic is a good shot of the raw response of the soundcard, * but it is still uncalibrated *.
> 
> ...


Okay so i pressed "make cal" and save the file, which is step 6. Step 7 tell how to delete which is not necessary and step 8 tell how to check the calibration. So i did step 6 prior to your last post. So somewhere is still not calibrated, which i thought step 6 did. I'll reread again and see what i missed. Again please be patient and i really appreciate your assistance.


----------



## janick (Mar 10, 2011)

EarlK said:


> I looked at that photo , you've made some progress but you're not quite there yet .
> 
> Your new pic is a good shot of the raw response of the soundcard, * but it is still uncalibrated *.
> 
> ...


Okay so i pressed "make cal" and saved the file, which is step 6. Step 7 tells how to delete which is not necessary and step 8 tells how to check the calibration. So i did step 6 prior to your last post. Somewhere it is still not calibrated, which i thought step 6 did. I'll reread again and see what i missed. Again please be patient and i really appreciate your assistance.:hail:

EDIT - i just went ahead and added that file to the mic/meter tab. i think that was the missed step? I'll run a test tonight.

EarlK - do you have a paypal account? When i get this finalized and start measuring i'd like to buy you dinner....


----------



## ddgtr (Nov 1, 2009)




----------



## EarlK (Jan 1, 2010)

- You must go through Step 8, to confirm that a newly created ( SC calibration ) file is (loaded) into the program ( & therefore offsetting the frequency errors of the soundcard / so that it now measures as a flat line ) .

- Do that ( Step 8 ) / then create a pic of the resulting response and post it here .

<> EarlK


----------



## janick (Mar 10, 2011)

EarlK said:


> - You must go through Step 8, to confirm that a newly created ( SC calibration ) file is (loaded) into the program ( & therefore offsetting the frequency errors of the soundcard / so that it now measures as a flat line ) .
> 
> - Do that ( Step 8 ) / then create a pic of the resulting response and post it here .
> 
> <> EarlK


So i did step 8. First i left the loopback. the next step was a little confusing because it said to uncheck the "c weighted SPL meter" in the mic/meteer tab. This was uncheck per your instructions in post # 9 during step 2. Anyways i hope this is correct but i'm a little worried the lines aren't close together like the instruction show. I left work today to complete this step as i'm dying to complete this step









If this is correct i will remove the loopback and connect to sc to SPL and AV. Could you advise on when i need to check the "c weight spl meter" and attched the file under the mic/mter tab

Also, not sure if you noticed in my last post but i would like to buy you dinner :T


----------



## EarlK (Jan 1, 2010)

janick said:


> Also, not sure if you noticed in my last post but i would like to buy you dinner


Thanks very much for the offer , in lieu of something for me , please donate a few bucks to this website .










The sound card sweep looks correct . Was the red line the actual loopback measurement ?

Assuming it was;

- reselect the "C" weighting option in the preferences,
- make sure your soundcard calibration file is loaded ( it should load automatically ), 
- get rid of the loopback, 
- attach you RS meter to one input ( or the other ), 
- make sure that input is selected in the preferences window, 
- connect an output to your receiver 

>>>>>> and now lets see if you can make a measurement ( after following the instructions for "Check Levels" ) .

<> EarlK


----------



## janick (Mar 10, 2011)

EarlK said:


> The sound card sweep looks correct . Was the red line the actual loopback measurement ?
> 
> Assuming it was;
> 
> ...


Yes the red line was the loopback measurement. I think its red because I don't have much "headroom" during the measurment. If i had more headroom then it would be green. I can play with that later after i first understand everything and actually make a valid measurement

I have practice for my son's baseball team tonight but will try that right after we are done. Question - everything makes sense except your comment to make sure the input is selected in the preference window. I have preferences open and looking at the "soundcard" tab. Are you referring to the "input channel" or the Input device which is currently set to default? Should i be looking at a difference tab? The mic/meter tab is set up.

I definitlely will donate as this website (and your services/advice) is excellent


----------



## EarlK (Jan 1, 2010)

*(i) Input Channel :*
- I was referring to the input channel ( L or R ) . 
- Even if the "Y" cable isn't marked , just plug the RS meter into one or the other side, tap the mic diaphragm ( set the mic to 60 db so that it is sensitive to a tap ) . 
- Watch the input meters and identify to "live" channel .
- Select that channel as the input channel .
- Reset the RS meter to read a higher db range / to prepare for a measurent ( maybe the 80 db setting is appropriate here ) .

*(ii) Input Device*
- When using the "Default Input" as your device selection , you must go to the computers audio control panel to make sure the computers input is set to "Stereo Mix" not "Microphone" / at least when using WinXP .



<> cheers


----------



## janick (Mar 10, 2011)

EarlK said:


> *(i) Input Channel :*
> - I was referring to the input channel ( L or R ) .
> - Even if the "Y" cable isn't marked , just plug the RS meter into one or the other side, tap the mic diaphragm ( set the mic to 60 db so that it is sensitive to a tap ) .
> - Watch the input meters and identify to "live" channel .
> ...


I thought i had the measurement but I'm worried about mic cal and sc cal lines as they are basically the same line.








I hope i'm close. By the why, each time i make a mistake the more i donate


----------



## janick (Mar 10, 2011)

okay so i couldn't go to bed until i tried one more time and here is the results after starting from scratch with a new calibration









looks to plain......again:scratch:


----------



## EarlK (Jan 1, 2010)

Janick,

*Please Read: Getting Graphs Ready To Post*  










*The preferred axis for a full range graphs is: *
VERTICAL = 45dB-105dB
HORIZONTAL = 15Hz-25,000Hz.

*The preferred axis for ALL subwoofer graphs is:*
VERTICAL = 45dB-105dB
HORIZONTAL = 15Hz-200Hz.


<> cheers

PS : Please, don't display phase information on your measurement graphs ( apart from SC calibration graphs ) , hardly anyone knows what to do with phase info, making it quite useless to display in a regular response graph .


----------



## EarlK (Jan 1, 2010)

janick said:


> looks to(o) plain......again


( Compensated ) Loopback Measurements are supposed to look boring since they are testing the linearity of the electronics for the ( now corrected & compensated ) soundcard /// just a bunch of ( mostly ) straight lines is what one expects will be displayed.

*- When are you going to make a sweep ( of a sub ) using the mic ( RS meter ) ?*
<> cheers


----------



## janick (Mar 10, 2011)

I though i was doing a sweep. its looks as though the mic cal and sc cal are set correctly.









Must have missed an important part; i guessing i need to tell it to measure a sweep?


----------



## ddgtr (Nov 1, 2009)

Hi, janick!

Did you:
- disconnect the loopback cable and connected it correctly to your RS meter and AVR?
- run "check levels" in "preferences", "sound card" tab?
- make sure everything else is ready for measurements as per Earl's directions above?

If yes, then select "Measure", adjust your start and end freqs and hit "Start Measuring"

Also, like Earl said, adjust your window so it goes from 45 to 105 on the vertical axis to about 20 to 20k Hz on the horizontal axis (although your RS meter might not go that high).

You can then adjust your waterfall graph to 200Hz for the sub readings.


----------



## EarlK (Jan 1, 2010)

janick said:


> Must have missed an important part; i guessing i need to tell it to measure a sweep?


Maybe !

Read the Help Topic *"Making Measurements"*  for a refresher on "how to make masurements" .

<> EarlK


----------



## janick (Mar 10, 2011)

EarlK said:


> Maybe !
> 
> Read the Help Topic *"Making Measurements"*  for a refresher on "how to make masurements" .
> 
> <> EarlK


Good morning,

Honestly i did a few times. I might start taking pics of each step i do. I'll try again


----------



## janick (Mar 10, 2011)

EarlK said:


> Maybe !
> 
> Read the Help Topic *"Making Measurements"*  for a refresher on "how to make masurements" .
> 
> <> EarlK


- when i hit measure the measuement setting are correct with 1 sweep
- i check levels and that if fine as well as headroom when i hit start
- no low signal or clipping
- looking at this http://www.hometheatershack.com/roomeq/wizardhelpv5/help_en-GB/html/measurementspanel.html#top
-i have the mic cal set as "with inverse c" but the directions posted above have it listed as radioshack which i have not option for. i think my error is here. in the preferences i have the soundcard calibrated to the coorect .cal. in the mic tab i check the "c weight" and trying measuring with both the .cal file as well as no file. When i use no file that is when i get the "inverse c" notification in the measurement panel. This i believe is the corect setting


----------



## janick (Mar 10, 2011)

ddgtr said:


> Hi, janick!
> 
> Did you:
> - disconnect the loopback cable and connected it correctly to your RS meter and AVR?
> ...


Hi ddgtr

yes to all above and when i select measure - the start and end fregs are correct at 0 and 10,000. The window is set corrrectly now as well. Again i think my error is in the little window to the left. it has "with inver c" for mic cal. The sc calibration is set to the correct .cal file. Not sure if the mic tab under preference should have a .cal file or nothing. The box is check though

FYI - made sure the stereo mix as pointed on in post #20

i feel it..i'm right there to having a valid measurement


----------



## janick (Mar 10, 2011)

i checked levels prior to "start measure" and those levels are fine. But if i turn of the spl meter and check levels again it still say levels are okay. I problem is the spl is not correctly connected to REW. i believe this has to do with the mic tab in prefences. Of course i calibrated the spl reading


----------



## EarlK (Jan 1, 2010)

janick said:


> (I) checked levels prior to "start measure" and those levels are fine. But if (I) turn of(f) the spl meter and check levels again it still say(s the) levels are okay. I (think the) problem is (that) the spl is not correctly connected to REW. (I) believe this has to do with the mic tab in pref(r)ences. Of course (I) calibrated the spl reading.


(i) When the *SPL meter is "OFF"* ( and then one runs a "check level" ) there *should be no input signal registering at either of REWs 2 inputs*.

(ii) If you do see input to REW ( at this point ) it means that either you've got your output signal looped into the input ( or the computers external mic is selected instead of the line/mix inputs ) .


(iii) Turn the SPL meter on ( make sure it's plugged into the computer through one side of that stereo mini Y-cable ) , open up the the "Metering" button in REW and talk into the RS mic ( set the RS mic to a level so that it doesn't overload when you talk into it ) .
- If your input connection is good , you'll see meter movement on the single channel ( which has the mic plugged into it ) . 

(iv) When using the RS SPL meter as a test mic / you don't select (check-off ) the "Mic Calibration" box .

<. EarlK


----------



## janick (Mar 10, 2011)

EarlK said:


> (i) When the *SPL meter is "OFF"* ( and then one runs a "check level" ) there *should be no input signal registering at either of REWs 2 inputs*.
> 
> (ii) If you do see input to REW ( at this point ) it means that either you've got your output signal looped into the input ( or the computers external mic is selected instead of the line/mix inputs ) .
> 
> ...


(1) This is my problem. It does register with the SPL off

(2)i have the output going to the AUX in the receiver and not looped. The input is going to the SLP meter only, with the other part of the Y adapter empty. So my problem is the computer's external mic is selected. So i went in the control panel's audio device and checked my volume and recording control. In recording control only Stero Mix is selected per your comment in post # 20. I played with this and when i uncheck Mix and select line in i did get the signal meter in REW to lower. In short, i decided to pick my sc in the soundcard tab and do away with the default setting. After playing with the input volume and think i got it working

Here is the moment of truth:









Does that look like a valid graph??


----------



## ddgtr (Nov 1, 2009)

Yes it does!!

The dips at ~42Hz and 65 would be considered fairly normal...

Now, with this graph loaded into REW, select the "waterfall" tab, then down on the lower left corner click on "generate" and post that graph also. It will show the decay and other additional useful info.

Go ahead and re-size the window to 20k Hz just to see what the response looks like above what you have listed so far (I understand the RS meter is only accurate to about 3k). Smooth that to 1/12 or 1/6 so it's a bit easier to follow.

You might want to also post the RT60 graph. It is generally agreed that it's more useful with larger rooms, but I think combined with everything else it might help a bit.


----------



## janick (Mar 10, 2011)

ddgtr said:


> Yes it does!!
> 
> Now, with this graph loaded into REW, select the "waterfall" tab, then down on the lower left corner click on "generate" and post that graph also. It will show the decay and other additional useful info.
> 
> ...


oh what a relief....Thank you for the feed back


----------



## ddgtr (Nov 1, 2009)

A couple of things:

Your second graph, post it as an SPL and NOT a waterfall, and it should go to 20,000 Hz not 20Hz.

Same with the RT60 graph, take it all the way out to 20,000Hz

Good job, I know exactly how relieved you must feel, this stuff is really confusing at first, especially when you try to set everything up...


----------



## ddgtr (Nov 1, 2009)

Also, resize the first waterfall graph to go to about 600-700ms instead of 300ms, this way we can better follow the decay.


----------



## janick (Mar 10, 2011)

ddgtr said:


> A couple of things:
> 
> Your second graph, post it as an SPL and NOT a waterfall, and it should go to 20,000 Hz not 20Hz.
> 
> ...


Thank you sir; it all seems straight forward now :whistling:


----------



## janick (Mar 10, 2011)

ddgtr said:


> Also, resize the first waterfall graph to go to about 600-700ms instead of 300ms, this way we can better follow the decay.


this part is much more fun..


----------



## ddgtr (Nov 1, 2009)

janick,

In your last post, the waterfall graph should NOT be a waterfall, but an SPL, the wavy kind of graph, two dimensional. So take very first one you posted in post number 32 above and resize the window to 20,000Hz.

THe waterfall graphs are only useful to about 200 Hz.


----------



## janick (Mar 10, 2011)

ddgtr said:


> janick,
> 
> In your last post, the waterfall graph should NOT be a waterfall, but an SPL, the wavy kind of graph, two dimensional. So take very first one you posted in post number 32 above and resize the window to 20,000Hz.
> 
> THe waterfall graphs are only useful to about 200 Hz.


Yep, i deleted and redid...took me a few seconds to realize the error


----------



## ddgtr (Nov 1, 2009)

Ok, now smooth it to either 1/12 or 1/6 and repost.


----------



## ddgtr (Nov 1, 2009)

And repost the waterfall graph with the 700ms window, make sure it only goes to 200Hz


----------



## janick (Mar 10, 2011)

ddgtr said:


> And repost the waterfall graph with the 700ms window, make sure it only goes to 200Hz


----------



## janick (Mar 10, 2011)

ddgtr said:


> Ok, now smooth it to either 1/12 or 1/6 and repost.


I know i saw the smoothing directions during my research but now having difficulty finding it


----------



## ddgtr (Nov 1, 2009)

In the pull down menus, under "graph". Or hit CTRL+SHIFT+6 for 1/6 smoothing.


----------



## janick (Mar 10, 2011)

janick said:


> I know i saw the smoothing directions during my research but now having difficulty finding it


Found it


----------



## ddgtr (Nov 1, 2009)

janick said:


> View attachment 30486


Yeah, you're rolling now!!

This is not a bad looking sub response. IF you have some flexibility, you can probably correct the few dips with physical placement of the sub or subs, plus a bit of eq.

Play around with the filters a bit, when looking at the waterfall graph click on the EQ box on top, then pull down the menus at the right side of the screen, and assign some filters and see what the predicted response would be. It's fun!

The long decay times at 20Hz are normal, I wouldn't worry about it as there is not much content down there.


----------



## ddgtr (Nov 1, 2009)

janick said:


> Found it
> 
> View attachment 30487


THis one does not look too bad either. Do consider this: with an RS meter with a calibration file loaded, you can only trust it to about 3k and I'm sure you can see it shooting up from there...

Your RT60 graph, it's around the 600ms threshold where most HT rooms are. I think the real values might be a bit higher.

I think with a bit of subwoofer placement and also some speaker placement you should be all right.

Perhaps some of the heavyweights will chime in also with more info... I know Earl has been a huge help!!


----------



## EarlK (Jan 1, 2010)

janick,

- Well I'm let-down that I missed your breakthrough !

- Anyways, glad to see you are up & running & _away to the races _( so to speak ) and are now getting good help from ddgtr .

- I'll add additional notes ( sometime this evening ) about a couple of important issues that I encountered ( while doing some research in between bouts of snow shovelling ) .

<> EarlK


----------



## janick (Mar 10, 2011)

EarlK said:


> janick,
> 
> - Well I'm let-down that I missed your breakthrough !
> 
> ...


The research about what the graphs mean are much more entertaining than the initial set up.


----------



## janick (Mar 10, 2011)

EarlK said:


> janick,
> 
> - Well I'm let-down that I missed your breakthrough !
> 
> ...


I never would of had the breakthrough with out your help. I look forward to your recommendations


----------



## EarlK (Jan 1, 2010)

*(A) ( Some Goals ) ;*

(i) One does want the response to be close to a straight line ( from 20 hz to 100 hz , +/- 2 db ) . 
(ii) Also, having a builtin straightline ( gentle ) downward slope ( with 20 hz being 3db louder than 100 hz ), can sound attractive ( IME ). 
- You've already got a nice start at that .
(iii) You need to somewhat fill in the holes at 40 hz & 80 hz . 

*(B) How do you accomplish the above ;*

(i) Holes can be filled in with a bit a EQ ( from a BFD ) . Though in my experience , if they don't react positively to 3 db of boost ( meaning , you don't get an actual 3 db improvement ) then you are fighting a loosing battle with nulls caused by room acoustics . Try 3db boost ( on a BFD ) at 40 hz, remeasure and see if the response improved . 

(ii) Move your sub around / again, remeasure and see if things improved .

(iii) Add another sub that doesn't reinforce the same room-nodes as the present one // 2-3 smaller types, are good numbers to work with . Put the second sub on one of the connecting walls ( vs the location of the main system ), @ in the middle of the wall & then remeasure .

(iv) Your problem at 80 hz may be phase related .
- To see if it is rotate the phase knob on your sub , remeasure and look for a change in the suckout ( hopefully an improvement will occur ) .


<> cheers

ps ; I'm now leaving it to others, to advise you on how to best improve the response of your sub-bass.


----------

