# Unable to Calibrate Focusrite Saffire Sound Card



## thinksyncopated (May 1, 2013)

Hello all!

I am running Mac OS X 10.8.3 and just downloaded REW. Unfortunately, I don't have a full grasp of what I am doing yet and just following the help menu, to no avail.

I have a Focusrite USB Soundcard (Saffire 6 USB) and the way I set it up is by connecting a 1/4" cable to the line out and XLR to the first Mic in. First, I don't know if this is the correct way to set up the "loop," but there are no line in options on the back of the sound card.

Then, in the settings menu, I assign the input channel to the left, set the input/playback knob on my card in the middle, and play around with the Mic gain and Monitor gain until the left output level reaches around -12dB. (the O/L light flashes red on my soundcard).

Unsurprisingly, there is 0.0dB headroom and the error message tells me there is clipping.

So - is my soundcard just incompatible? Have I set up the loop incorrectly? Am I adjusting the knobs incorrectly? Perhaps the menu options I chose were incorrect?

I can provide additional information as necessary, but hope the good folks here can help! :help: I purchased an ECM-800 to continue the testing, but it looks like I'll have to get past the soundcard calibration first...

Thank you!


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## JohnM (Apr 11, 2006)

thinksyncopated said:


> set the input/playback knob on my card in the middle


The Mixer knob needs to be turned all the way around to 'Playback', don't want any of the signal the soundcard is measuring to be sent straight back to the output.

Also need to go through this thread to get REW set up for using a multi-channel USB card on OS X.


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## thinksyncopated (May 1, 2013)

Thank you John! I followed the instructions provided through the link to set up the sound card, set the knob all the way to playback, and adjusted the input gain and monitor gain to levels that did not cause clipping.

This is the calibration graph that came out as a result. Does this look like a suitable calibration file for my sound card?:huh:


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## JohnM (Apr 11, 2006)

Afraid not, looks mostly like noise. You are using a very old version of REW, best updating to the latest beta from here.


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## thinksyncopated (May 1, 2013)

Thank you for the reply. I installed the beta and tried again, this time playing around with the input gain and monitor controls to set them as parallel as possible. This is what I have now. Looks much better to me. What do you think?


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## JohnM (Apr 11, 2006)

Looks perfect. The phase plot is showing that the overall signal path is inverting, can tick the "Invert" box on REW's soundcard prefs input options to correct that.


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## thinksyncopated (May 1, 2013)

Thanks again John! 

I went ahead and clicked the invert button (still using the last calibration file).

I also uploaded the generic ECM8000 calibration file, checked the levels, and started the first measurement. 

I placed the mic horizontally, equidistant from my near-fields (Yamah HSM80s), at about ear level.

Here is my first graph. Based on others I have seen, does not look useable. I am still reading through guides to understand how to interpret the data, but want to make sure it is measured correctly. Please let me know how this looks - thank you!


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## JohnM (Apr 11, 2006)

Try using these graph setting suggestions and measuring with only one speaker turned on at a time. If you post the mdat file can check all is OK with the measurement. You can deselect the phase plot, not needed for looking at room response.


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## thinksyncopated (May 1, 2013)

Thanks John. I tried again with the left and right speakers separately. There was more feedback with the left speaker so I had to change the levels slightly. Not sure if this impacts the readings significantly. .mdat file attached.


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## JohnM (Apr 11, 2006)

thinksyncopated said:


> There was more feedback with the left speaker so I had to change the levels slightly


Any feedback at all is a big problem, you must get the system set up so that nothing on the input gets fed back to the output - measurement systems work by generating a test signal and capturing the system's response to it, if the actual signal that is output is the test signal plus a bit of what is coming back you will not get a valid result.


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## thinksyncopated (May 1, 2013)

Hi John,

Thank you for the feedback (pun intended ). I made sure there was no feedback and that the levels for the right and left speakers (when tested separately) were within +-.1dB or so. The attached .mdat file contains measurements for the left and right speakers separately, as well as both speakers together.

I figured I would post the results to this thread as I have already begun a dialogue on my progress. Hopefully someone can help me interpret the results of the measurements! 

Thank you


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## thinksyncopated (May 1, 2013)

.mdat attached


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## thinksyncopated (May 1, 2013)

Not sure why the file is not attaching. Please find the graph below. Used "standard" limits and 1/3 octave smoothing.

Red: Left Speaker
Purple: Right Speaker
Teal: Both Speakers


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## JohnM (Apr 11, 2006)

Looks OK, but 1/3 octave smoothing hides a lot. How big was the mdat you were trying to attach? Upload limit is just under 10M.


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