# UCA202 line-out questions



## fight4yu (May 31, 2010)

Hi. This is my 1st post.. thanks for all the information provided in this forum so far. It is very helpful 

I got my UCA202, RS SPL meter, and also REW, and here is my connection:

SPL Meter -- (RCA cable) -- UCA202 Input L.
UCA202 Output L + Output R -- 2x RCA cable -- Receiver Stereo L and R input.

And in REW, I pick "L" as input channel.

Is the the right connection? I am not sure about the output of the UCA202.. The tutorial here seems to suggest I use the L output and then have a splitter to the receiver Stereo L and R input.. However, given UCA202 already have a R output, I assume I can just use that and not use a splitter?? Is there any problem?

Also, I found that if I use the "speaker output to check level", my SPL measurement on the main speaker seems to be 3-4 dB lower, compared to if I just use the receiver internal test-tone to get to 75dB.. I also try using DVE test-tone and it also match with my receiver test-tone. So, it seems like REW check level is somewhat lower for my main speaker?? Anyone can explain what I have done wrong?

Thanks


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## JohnM (Apr 11, 2006)

The signals from REW are affected by your receiver's volume control, internally generated test signals are (generally) not. The REW signal is for checking that the soundcard input levels are reasonable, not for calibrating absolute speaker levels.

You can drive your receiver directly from the two outputs of the soundcard, but it does mean you cannot then use one soundcard output as a timing reference loopback connection. That is not required for most measurements, however, so you are fine as you have currently set things up.


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## fight4yu (May 31, 2010)

Thanks John for your reply!
BTW, I am now considering the MobilePre and the ECM8000. That will cost me about $150, but I assume I will have better accuracy. My main focus is on tuning my subwoofer. Can someone quantify what the added accuracy and benefit will be comparing the Radio Shack Meter that I have currently? If it is within +/-1 dB for measurment, I think I am fine with my current setup. However, if it is more than +/- 3dB, then I will really want to get the ECM8000/MobilePre combo.
Thanks.


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## JohnM (Apr 11, 2006)

For subwoofers the RS meter is fine, there is no need for a measurement mic. A mic becomes useful if you need to make measurements above about 2kHz.


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## fight4yu (May 31, 2010)

Thanks John! Your reply just save me about $150 
And thanks for the excellent REW software.


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