# Calibration of Sound Card Question



## fkcfkc (Jul 26, 2010)

When you go through the settings it says just to use the right channel to calibrate the sound card. Do I do i only use the right channel output and input ith my y adapter or do a just use a different 3.5 mm to 3.5 stereo cable to loop it? Is it critical that I use the exact same cables and adapters that I am using later for calibration. I got it to work with the 3.5 to 3.5 cable (which has both channels, but I wont be using it as I progress through the later steps.

Also when adjusting levels before measuring, it says "keep it below -1" Does that mean -2, -3, -4 (quieter)? Or does it mean that it should be "louder" ie 0, +1, +2

I am guessing that it should be -2, -3, or -4..


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## JohnM (Apr 11, 2006)

A stereo loop back is OK, you don't have to use the same cables as when measuring (but if you do you are sure they are OK )

Below means more negative, the maximum reading on those meters is 0dB FS, which is full scale input.


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## glaufman (Nov 25, 2007)

+1. You also may want to post plots of your calibration as sometimes we pick up anomalies new users don't know to look out for.


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## fkcfkc (Jul 26, 2010)

OK, here goes.

I connected a 3.5 mm to male rca cable in the mic output of my Del Latitude D420 and set it to line in mode. IN the speaker jack, I put in a 3.55 to rca female adapter in there. I plugged the right rca into it.

I ran the calibration per the users manual. I made sure to clear the Radio Shack .cal file and take off C weighting before running the second graph.

I am really proud of myself for learning all of this and the progress I made of understanding it thus far. :T I took a stab at adjusting my notch filter and EQ and would really appreciate someone double checking what I think was the right adjustment to make. Post is here http://www.hometheatershack.com/forums/rew-forum/31466-need-some-deciphering-help.html

Here are my 2 calibration graphs


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## glaufman (Nov 25, 2007)

I'd say you're close, but something's not quite right.
First, from the second graph, it looks like your soundcard calibrated OK. That's the dashed black trace. But, in that graph, what's the purple trace? If I assume that's a measurement sweep taken with a loopback cable, there are 2 issues: 
1: It looks like your level is set too high, the level of this trace should be lower.
2: That trace should be perfectly flat. It's possible that having the level too high could distort things, but I wouldn't expect the level that you're at to distort things yet. So I think there's another issue.

As for the first plot, I see that's the magnified version, but what's the solid black trace, and the solid blue trace?


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## fkcfkc (Jul 26, 2010)

Input Volume is .084
Sweep -9.0
Wave Out1
Output .516

1st graph

solid blue soundcard .4 db
dotted blue corrected .4 db
solid black mic meter cal -6.4 db
dotted black soundcard cal .7

2nd graph

solid purple - it says the date I ran the test 89 db
dotted purple - corrected 89db (its under the solid)
Solid blue - Target -.125db
dotted black - soundcard cal .1db


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## JohnM (Apr 11, 2006)

> Input Volume is .084


That suggests the input might have been in mic mode, would expect a higher input level for a line input.


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## fkcfkc (Jul 26, 2010)

just to clarify, when I wrote this in my post:

Input Volume is .084
Sweep -9.0
Wave Out 1.0
Output Volume .516




those were not readings. Rather they are where I set those values in the settings page. I could always raise them if I wanted to.


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## JohnM (Apr 11, 2006)

If 0.084 is the input level that gave an input reading close to the output reading during the level setting process then that is lower than I would expect for a line input, which is what makes me suspect it may have been in Mic mode - that would also explain the somewhat noisy trace.


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## fkcfkc (Jul 26, 2010)

I can't figure out how to get it out of "mic mode" when it says "line in". No where does it indicate Mic mode....Maybe I jsut need to borrow a better laptop?
I have the output "speakers" set as headphones in my control panel. Shouyld it be something else (eg "computer speakers"

How much of an impact do you think this had on my graph and my subsequent adjsutment of my notch filter?

Thanks


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## JohnM (Apr 11, 2006)

Using the headphones setting is fine. The effects on your measurements would be small and shouldn't affect your adjustments, it just isn't quite as it should be.


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