# Room EQ Wizard unhappy after Measure Soundcard Response



## blekenbleu (Jan 4, 2007)

Downloaded V3.29 this afternoon; decided to try a built-in laptop soundcard
in spite of only Mic in and Headphone out; got a response very similar to:
http://www.hometheatershack.com/roomeq/wizardhelp/images/realteksc.jpg
.. but when subsequently trying to verify the calibration,
selecting and deselecting C weighting MADE NO DIFFERENCE. 
Manually resetting the upper sweep limit to 200Hz had no effect;
sweeps ran to 20kHz or so.

Selecting and deselecting C weighting is effective after
quitting REW, restarting and loading the saved soundcard calibration,
so it is an easy bug to work around.

Windows XP SP2 and J2SE Runtime Environment 5.0 Update 10.

BTW, I made Dell D520 Mic input useful by putting an 8uF non-polarized cap
in series with an 82K resistor, with a 10K resistor to ground at the other end.


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## brucek (Apr 11, 2006)

> but when subsequently trying to verify the calibration, selecting and deselecting C weighting MADE NO DIFFERENCE


You have to load the saved soundcard calibration file before it takes effect..



> BTW, I made Dell D520 Mic input useful by putting an 8uF non-polarized cap
> in series with an 82K resistor, with a 10K resistor to ground at the other end.


Although you can make laptop microphone inputs work by blocking the DC and dividing the signal lower, usually they're not too suitable for line level signals since their gain is quite high which results in an extremely poor noise ratio. Many of these inputs also suffer a limited frequency response since they are designed for microphone voice bandwidth.. The external USB cards offer really good results with limited expense.

brucek


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## blekenbleu (Jan 4, 2007)

brucek said:


> You have to load the saved soundcard calibration file before it takes effect..


 I had and it was; response was nominally flat;
it was Meter C Weighting that was being ignored.



brucek said:


> Although you can make laptop microphone inputs work by blocking the DC and dividing the signal lower, usually they're not too suitable for line level signals since their gain is quite high which results in an extremely poor noise ratio. Many of these inputs also suffer a limited frequency response since they are designed for microphone voice bandwidth.. The external USB cards offer really good results with limited expense.
> brucek


I've no argument with that and have an Extigy to deploy
when I get a BFD and calibrated mic.
Meanwhile, for scooting around and making coarse corrections
by speaker placement and crossover adjustments, etc,
it's handy to involve as little equipment as possible.
REW shows over 60dB between lowest sub sweep response and no signal,
so I'm happy.


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## blekenbleu (Jan 4, 2007)

brucek said:


> You have to load the saved soundcard calibration file before it takes effect..


I have not figured out a button sequence to make it use a fresh measured response
without first exitting and restarting Room EQ Wizard;
save and load does not suffice.


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## brucek (Apr 11, 2006)

*Clear* first, then *Load*.....


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