soundcard calibration graph

[stepyourgameup]

How does this look?

[brucek]

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]

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

[stepyourgameup]

ok, how does this look?

[brucek]

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]

brucek wrote:

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

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]

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]

I see. Thanks.

[stepyourgameup]

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

[brucek]

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]

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]

[stepyourgameup]

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

[thewire]

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

[stepyourgameup]

thewire wrote:

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

So the soundcard calibration is good then?

[Ricci]

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

This is just a loopback measurement of the SC right?

[stepyourgameup]

Ricci wrote:

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

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]

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]

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



I think we have a weiner.

[stepyourgameup]

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

[JohnM]

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]

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

[carls64]

Much better, carry on...

[stepyourgameup]

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

[brucek]

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