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Discussion Starter #1
Hi folks,

I have a problem and not the slightest clue about it::help::dontknow:

I'm trying to generate seperate SPL curves for the left and right channel, using a Windows-8-Laptop, an M-Audio FastTrack USB-Soundcard through ASIO, a Superlux ESM999 Mic, fullrange stereo-amp+speakers and REW 5.0. The FastTrack should be full-duplex, so I'm using it as an input and output device.

Everything is fine while I'm working on the left channel (i.e. only the left channel connected from FastTrack to amp). But using the right channel in REW (i.e. connecting only the right channel between FastTrack and amp and switching to "input right" in the soundcard preferences window) yields a strange result: still the level meter of the LEFT (!!!) channel shows a signal while the level meter of the right channel remains lifeless. At the same time sound comes from the right speaker (in corellation with the hardware path) and REW says "level is low at -95.8dB" in the measurement window (->check levels). Of course that constellation yields no valid SPL curve.

BTW: everything works fine e.g. with Acourate software (but I need .txt-output which Acourate doesn't provide).

What am I doing wrong?:crying::hissyfit:
Thank you in advance,
Eunegis
 

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REW Author
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6,711 Posts
Unless you are swapping the mic from left to right channel you should leave the input channel selection on Left, as it was, just move the output channel (as you have done).
 

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Discussion Starter #3
But it didn't help...!
The FastTrack has one single inlet for a balanced mic cable/plug - it cannot be swapped from left to right.
The only way I can think of is to let the program run as "recording on the left channel" all the time, but connect the right channel instead. That way the right side would simply be recorded through the left channel. Its a little awkward - but do you or anyone else know a more elegant way?
 

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REW Author
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No, that's exactly what you should do. It doesn't matter what input channel you use as long as you have the mic connected to it! Input and output channels are independent, use whichever output channel you want (REW puts its test signal on both output channels) and just connect whichever output channel you have decided to use to the amp channel you want to test.

Edit: just noticed you are using ASIO. To have the test signal appear on both output channels select the other channel as the timing reference output.
 
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