# soundcard calibration graph



## stepyourgameup (Jul 30, 2008)

How does this look?


----------



## brucek (Apr 11, 2006)

Can't really tell much from that graph.

If this is your soundcard calibration file, the vertical axis should be -3dB to +3dB and the horizontal axis should be 2Hz-~20KHz.

You've only shown a small portion.

brucek


----------



## stepyourgameup (Jul 30, 2008)

I will try to post the whole graph tonight when I get home. Thanks Bruce.


----------



## stepyourgameup (Jul 30, 2008)

ok, how does this look?


----------



## brucek (Apr 11, 2006)

Not good. There's a problem.

It may be that you have a 'monitor' mode turned on in the soundcard. This results in the line-in being enabled in playback (checkable in the windows playback mixer).

Examine the soundcard application software and see if a monitor is enabled.

brucek


----------



## stepyourgameup (Jul 30, 2008)

brucek said:


> Not good. There's a problem.
> 
> It may be that you have a 'monitor' mode turned on in the soundcard. This results in the line-in being enabled in playback (checkable in the windows playback mixer).
> 
> ...


I thought so, but I can't seem to find where to turn that off! I am running windows XP with a C-Media sound card. Any suggestions?

edit: The advanced settings for sound recording is greyed out. I'm guessing that is where I need to go to change the loopback setting.


----------



## brucek (Apr 11, 2006)

Take a look at the Windows Mixer in Playback (as shown below) and see if the line-in is muted. 
It should be to shut the monitor off. Check this with REW running.

Simply double click the speaker icon in your desktop system tray.











brucek


----------



## stepyourgameup (Jul 30, 2008)

I see. Thanks.


----------



## stepyourgameup (Jul 30, 2008)

Ok, my output looks like what you showed. Here's my recorder settings. No change in my graph yet.


----------



## brucek (Apr 11, 2006)

Looks good.

OK, can I see a screen shot of the REW Settings page......

BTW, you are using stereo plugs into line-in and line-out, and you've broken out the right channel and have a cable connected between line-out to line-in, with the left channel remaining open.

brucek


----------



## stepyourgameup (Jul 30, 2008)

Here's the screenshot. I have two stereo plugs plugged into the soundcard. I have an RCA cable plugged into both red females and the whites are empty.


----------



## stepyourgameup (Jul 30, 2008)




----------



## stepyourgameup (Jul 30, 2008)

I ran it again and got a better response this time.


----------



## thewire (Jun 28, 2007)

Change the sweep level to -18db FS. Then calibrate your sub to 75dB.


----------



## stepyourgameup (Jul 30, 2008)

thewire said:


> Change the sweep level to -18db FS. Then calibrate your sub to 75dB.


So the soundcard calibration is good then?


----------



## Ricci (May 23, 2007)

Still looks like there's some interference or distortion there. The midrange dip is strange. If this is a lap-top try turning your wifi off and make sure you are running off of the battery pack and not the wall. Also check your levels to insure that something is not overloaded. May possibly be the sampling rate used? I had a problem like this when I first started, but I can't remember exactly how I corrected it:scratchhead:

This is just a loopback measurement of the SC right?


----------



## stepyourgameup (Jul 30, 2008)

Ricci said:


> Still looks like there's some interference or distortion there. The midrange dip is strange. If this is a lap-top try turning your wifi off and make sure you are running off of the battery pack and not the wall. Also check your levels to insure that something is not overloaded. May possibly be the sampling rate used? I had a problem like this when I first started, but I can't remember exactly how I corrected it:scratchhead:
> 
> This is just a loopback measurement of the SC right?


Yes, just a loopback measurement of the SC. It is a desktop. It could be a soundcard. I could use another computer if I need to or buy a new SC. What is a good inexpensive SC to buy?


----------



## brucek (Apr 11, 2006)

> So the soundcard calibration is good then?


No. (note that the best sweep level for soundcard cal is usually ~-6dBFS)

Why haven't you selected the soundcard in the Input / Output selection pulldowns? (example below)










brucek


----------



## stepyourgameup (Jul 30, 2008)

I thought it said to use the default device. :duh:
Check this graph out then.









I think we have a weiner.


----------



## stepyourgameup (Jul 30, 2008)

Here is the subwoofer range from the same graph as above.


----------



## JohnM (Apr 11, 2006)

There is something very wrong with all the soundcard plots you have shown, they are not correct measurements. Are you using the Measure... button on the soundcard settings to make the measurements? Odd that the Line In volume is set so low on the screenshot you posted of the Record settings. Worth taking a look at the Scope graph tab after making the measurement to see what the captured signal looks like.


----------



## stepyourgameup (Jul 30, 2008)

Ok, I borrowed my brothers computer and got this graph. Look ok?


----------



## akakillroy (Jul 9, 2008)

Much better, carry on...


----------



## stepyourgameup (Jul 30, 2008)

Ok, I checked SPL levels and loaded the SPL cal file for my galaxy 140. Here is my graph.


----------



## brucek (Apr 11, 2006)

> Here is my graph.


With the Graph Limits button, set the Vertical axis to 45dB-105dB and the Horizontal axis to 15Hz-200Hz.

Use a Measure limit from 0Hz-200Hz.

Use a Target level of 75dBSPL.

Then repost the graph.............

brucek


----------



## stepyourgameup (Jul 30, 2008)

Question. My SPL reading in REW says 75db but my SPL meter is only at 45db. This is without playing anything from my receiver. Is this normal? I hooked up a stereo plug/RCA splitter to the Galaxy and I am only using the right channel so the left channel is not being used.


----------



## brucek (Apr 11, 2006)

> My SPL reading in REW says 75db but my SPL meter is only at 45db. This is without playing anything from my receiver. Is this normal? I hooked up a stereo plug/RCA splitter to the Galaxy and I am only using the right channel so the left channel is not being used.


I am completely baffled about what you are asking????

Try again.

brucek


----------



## stepyourgameup (Jul 30, 2008)

Here is what I was referring to. It says 75db with nothing playing. When I look at the meter itself, it is measuring 45db.









then when I go to set the target level, it says that the meter reading is around 75db without the test tone even playing.


----------



## brucek (Apr 11, 2006)

Ahh OK. You forgot to run CALIBRATE. 

See that button in your jpg above called Calibrate.

This is to align/sync/match the actual level of your real SPL meter to the REW SPL level shown on its meter (how else would it know if you don't tell it?). You have to run the Calibrate at the correct time though.

Run the settings tabs Check Levels routine and set the actual SPL level at your listening position to 75dB using your receiver volume control. Then set the Input level of the soundcard in REW.

Then press CALIBRATE and match the two meters......

I guess you missed that section when you read the REW HELP FILES

brucek


----------



## stepyourgameup (Jul 30, 2008)

I thought I did all that. I will try again tonight. Thanks.


----------



## stepyourgameup (Jul 30, 2008)

I finally got it working right. Here is my first graph. Look at that dip after 50hz. I will run audessey and see if it helps.


----------



## stepyourgameup (Jul 30, 2008)

And this is after audessey. The measurments I got from audessey were accurate according to speaker distances.


----------



## brucek (Apr 11, 2006)

Use a vertical axis of 45dB-105dB in your graphs.

Set the target cutoff in REW to the crossover you're using so we can see how close you are to the target (i.e. 80Hz). Looks like you have it set to about 100Hz. Is that your crossover?

brucek


----------



## stepyourgameup (Jul 30, 2008)

The crossover is set to 80 on both REW and my Denon.


----------



## brucek (Apr 11, 2006)

You do have a couple peaks at 25Hz and between 40and 50Hz that could be easily helped with equalization. The dip at 70Hz might go away when you add the mains and play with the subs phase control a bit. Try adding the mains and take another measure to see what happens with that. Don't change anything in the way you take the measurement when you add the mains other than rerun the Check Levels.

brucek


----------



## stepyourgameup (Jul 30, 2008)

brucek said:


> You do have a couple peaks at 25Hz and between 40and 50Hz that could be easily helped with equalization. The dip at 70Hz might go away when you add the mains and play with the subs phase control a bit. Try adding the mains and take another measure to see what happens with that. Don't change anything in the way you take the measurement when you add the mains other than rerun the Check Levels.
> 
> brucek


My mains really suck right now. I am planning on adding 2 MBMs so they should help in that area. Do you think I really need an EQ? Is there anything else I can try to help with that dip at 70hz? I will be adding bass traps in the very near future.


----------



## brucek (Apr 11, 2006)

> Do you think I really need an EQ? Is there anything else I can try to help with that dip at 70hz? I will be adding bass traps in the very near future.


Yeah, you need to lower the peaks you have. The one at 25Hz is significant enough to cause a bit of trouble.
You can't worry about the 70Hz dip until you add the mains and see what happens. It's too close to the crossover to play with before you test that.

Traps won't help the frequencies below 80Hz unless they're so large you wouldn't be able to get in the room with them.....

brucek


----------



## stepyourgameup (Jul 30, 2008)

brucek said:


> Yeah, you need to lower the peaks you have. The one at 25Hz is significant enough to cause a bit of trouble.
> You can worry about the 70Hz dip until you add the mains and see what happens. It's too close to the crossover to play with before you test that.
> 
> Traps won't help the frequencies below 80Hz unless they're so large you wouldn't be able to get in the room with them.....
> ...


So your saying that a superchunk corner trap wouldn't do anything? Those things are 12" thick in the middle.


----------



## brucek (Apr 11, 2006)

> So your saying that a superchunk corner trap wouldn't do anything?


We're really starting to get outside the purview of the REW section. 

Questions about acoustics are best directed to our Acoustics Section. 

There are lots of guys that know about room treatment there.

brucek


----------



## stepyourgameup (Jul 30, 2008)

Hey Bruce, This was taking tonight with the SPL placed in the middle between the two rows of seats with the mains turned on and xover at 80hz.


----------



## stepyourgameup (Jul 30, 2008)

I finished installing my corner super chunk bass traps and I took some measurements. The green graph was before the bass traps, sub was crossed over at 80hz. The gold is the new one with bass traps, crossed over at 100hz. Green's target level was 72.6dB and the gold was 77dB.









Here is tonights graph by itself.


----------



## stepyourgameup (Jul 30, 2008)

Here is another graph from tonight but on the other side of the couch.


----------



## thewire (Jun 28, 2007)

Looks pretty good. When I was finding that the right and left seats sounded different, I played sine waves where these frequencies were different. I found lower frequencies to be very difficult to track, but I found some areas around the 80Hz and higher to be related to my temp center channel stand, which only is a shelf with some various things in it. Moving it inches left, right or forward smoothed out the differences, as well as placing more absorption inside it. I did not measure the differences yet (or I might have, not sure) but it really helped. I think you might be able to do something similar for the 45Hz - 65Hz if it is a similar situation, where maybe moving some furniture of gear in the middle of the room may help.


----------



## stepyourgameup (Jul 30, 2008)

I have decided to get a BFD to help with the peaks.


----------



## thewire (Jun 28, 2007)

stepyourgameup said:


> I have decided to get a BFD to help with the peaks.


It looks like it will not be so difficult to get a good result from a BFD, and maybe some other subtle changes to the positioning. If you measure with the BFD after you have uploaded filters to it, the bypass will not work so using the other input side of the BFD, or deleting filters will give you a new response worthy to add new filters.


----------



## brucek (Apr 11, 2006)

> If you measure with the BFD after you have uploaded filters to it, the bypass will not work


Not true..........

brucek


----------



## thewire (Jun 28, 2007)

When I use bypass with filters there is noise and when I delete filters then turn off the bypass there is not. Sorry.


----------



## brucek (Apr 11, 2006)

> When I use bypass with filters there is noise


There shouldn't be (unless you had a filter that reduced a noise you happen to have in your system already), but generally there is no noise specific to the bypass while having loaded filters.

brucek


----------



## thewire (Jun 28, 2007)

brucek said:


> There shouldn't be (unless you had a filter that reduced a noise you happen to have in your system already), but generally there is no noise specific to the bypass while having loaded filters.
> 
> brucek


Sorry to the OP I don't mean to hijack the thread. The noise is a very faint hiss noise, and might not be obvious if one is using a crossover, as I do not when measuring. I only use one filter currently.

http://www.flickr.com/photos/tns29/2927408968/sizes/o/


----------

