Behringer UCA222 help.

Gmauro

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Hello everyone, I am a new member and I need your help. I installed rew on my notebook which has no microphone input, so I bought a Behringer uca222 external card to be able to make impedance measurements, but I have many problems:
1- after the sound card calibration, the resulting graph is what you see in figure 1. extremely noisy after 1 khz.
2- if I try to do the calibration in 3 steps (open circuit, short circuit and reference cal) at step 2 the error you see in photo 2 always appears. I can't understand how to make it read the difference in level between the value detected and the reference one (which I don't understand what it is)
3- if I also try to make an impedance measurement on a loudspeaker, I have a result as in figure 3. Which has no similarity with an impedance measurement.
Could I tell you that:
- connections are correct, no short or missing mass. I use a 110 ohm carbon resistor, but even with a 90 ohm MOX nothing changes.
- use of the headphones output of the UCA222
- I have disabled the default input and output of the computer to transit exclusively through the UCA222.
Other I don't know what to tell you. Please help me.
Thank you all.
Mauro
 

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John Mulcahy

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The measured value is the reading from the load. For a short circuit calibration that would be a connection to ground, so should be close to zero volts. The reference input is the loopback from the output, so its level should be close to the sweep level. For both to read the same a possible cause is that the input is configured in the Windows audio properties (Advanced tab) as mono.

Note that you should select the actual input device, input, output device and output you are using on the REW soundcard preferences rather than leaving them as default.
 

Gmauro

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The measured value is the reading from the load. For a short circuit calibration that would be a connection to ground, so should be close to zero volts. The reference input is the loopback from the output, so its level should be close to the sweep level. For both to read the same a possible cause is that the input is configured in the Windows audio properties (Advanced tab) as mono.

Note that you should select the actual input device, input, output device and output you are using on the REW soundcard preferences rather than leaving them as default.
Many thanks John for your reply. During this night i've solved my problem exactly by changing mono to stereo setup in windows audio option.
But now, when i make 3 steps calibration process, at the end of step 1, i've the following message. See the attached pics.
I don't understand why and if this is a problem for make real measure. what do you think?
Is true, that the measure that i've done during my test is very good, compared with the same measure done by clio after and rew now. Also measurments on a 3 different resistor is perfectly matched whit measured value.
 

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Gmauro

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Wow! that's sonds good!
Now, merry christmas and happy new year!
 

Gmauro

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That's OK, seems to be a feature of that interface.
Hi John, after few months without using rew, i have again some problem with impedance measurments with my behringer UCA222, please see attached pictures.
Soundcard calibrationd was ok, but i'm not able to do 3 step manual calibration. when i end point 2 i've the message "short circuit measurment not valid".
Do you see some error in my setup? have you any advice to help me?
Of course, i've check the mono / sereo setup in advanced windows setup, and appear all ok.
From the last measurment without any problem to today, the only changes occours is some windows update, rew update, and no other.
Thanks for support
Mauro
 

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John Mulcahy

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The Configure button of the audio properties is not really relevant. Check the Advanced tab of the Audio properties to make sure the Default format is a stereo format, one cause for the reference and measurement input showing the same value is having a mono format selected, but REW should detect that. Otherwise there may be a wiring problem, if the measurement connections were really shorted for the short circuit measurement it would not be possible for both inputs to have the same reading.
 

Gmauro

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The Configure button of the audio properties is not really relevant. Check the Advanced tab of the Audio properties to make sure the Default format is a stereo format, one cause for the reference and measurement input showing the same value is having a mono format selected, but REW should detect that. Otherwise there may be a wiring problem, if the measurement connections were really shorted for the short circuit measurement it would not be possible for both inputs to have the same reading.
Where i can find the advanced tab of the audio property? What is the path?
About wiring problem this is very strange, because this is the same cable that i've used from the firs time.
I will suspect some windows setting changed during software upload... but i will check also the cable.
 
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