# Problem calibrating USB Soundcard



## somm (Feb 19, 2012)

Hello to all,

since this is my first post please do not blame me if I put it in the wrong forum. I have read around the forum to get my problem solved, but I found nothing that matched it. So, here is the description:

I have setup REW on 2 computers (One XP 32 Bit and a second Win 7 64 Bit). Also the latest drivers for my USB sound card Focusrite Scarlett 6i6. The I wanted to make a sound card calibration. So I disabled all the internal routing in the Mixer from the 6i6 to get rid of a loopback.

Then I connected the Mic1 to the Mon1 with an XLR to TR cable, selected Mic1 as input and Mon1 as output in REW and started the calibration.

I use a Sweep Level of -12. I get an signal on the input but when I turn up the Monitor AND the Gain of the Mic I am only able to get -38 on the input.

Same on both computers, I cannot get near the -12 .............

So is there anybody out there who also has an 6i6 and the problem solved or is it ok for this kind of interface to make the calibration with a Sweep Level of e.g. -35 ????

Thanks for the help


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## jtalden (Mar 12, 2009)

Welcome to HTS!

Possibly the loopback cable is shorting the signal? 
Is it a custom cable? If so, it may be wired wrong.
If it is a purchased XLR to TS then it is likely the problem.

A standard XLR to TRS cable is the normal safe choice and can be expected to work properly.


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## somm (Feb 19, 2012)

I bought this cable and I also see that it seems to be working (I see input on the Mic1 channel but I cannot adjust it high enough to get near the -12 Sweep Level).

The Scarlett 6i6 can be used with balanced TSR and unbalanced TR cables (this says the manual). So do you think using a XLR to TSR will solve the problem?


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## jtalden (Mar 12, 2009)

Maybe someone else will know for sure. I only know that I inadvertently once purchased an XLR to TS cable that was apparently intended to convert a unbalanced XLR stereo output to a unbalanced mono input. That cable shorted the balanced signal so that only a very low signal was leaking through. Some other XLR to TS cables are wired to convert a Balanced XLR signal to an unbalanced TS signal and those should work.

It's also possible that your setup in REW or 6i6 is the issue, but if you can take a measurement with a mic on the left channel using in/out #1 then that is not the issue.

REW should be set to Left channel for both input and output for calibration with your current loopback cable connection. [The REW default is set to use the right channel but using the left channel is fine so long as the REW change is made.] If REW is set to the Right channel you can also just move the loopback cable to in/out #2.

If your 6i6 interface is like my Focusrite Saffire interface then I just hold Control-Shift and left click on the output channel buttons on the lower right corner to turn them light blue instead of dark blue (or red). This bypasses the mixer completely and routes the inputs to the outputs.

Good luck!


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## Wayne A. Pflughaupt (Apr 13, 2006)

I’d suggest calibrating using the line input rather than the mic input. The front panel inputs are combination jacks that will accept XLR or 1/4” plugs. You can use a TRS to TRS cable, or a TS to TS cable for the loopback from the outputs.

If all else fails, you probably don’t even need a calibration. Most interfaces these days have virtually ruler-flat response. My TASCAM US 122 does, and it was half the price of your Focusright. 

Regards, 
Wayne


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## somm (Feb 19, 2012)

Ok, will try to calibrate using an TR - TR cable from Mon1 connected to Mic1.

Does it make sense to calibrate with an lower Sweep Level or is this not good ?


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## somm (Feb 19, 2012)

I have tried it now with an TRS - XLR cable. Now the level seems OK for an calibration, but when I try to make an calibration I get an warning from REW and the measurement looks strange.


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## jtalden (Mar 12, 2009)

Possibly there is feedback from the input to the output due to the 6i6 settings? I think the 6i6 mix control interface is setup similar to my Saffire mix control?

Above I remembered wrong as to how I have my saffire setup. See *Here* to better explain. 

If that is not the problem you will probably need to provide some more information as to the warnings and what your specific setting are.


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## Wayne A. Pflughaupt (Apr 13, 2006)

somm said:


> I have tried it now with an TRS - XLR cable. Now the level seems OK for an calibration, but when I try to make an calibration I get an warning from REW and the measurement looks strange.


TRS to XLR still puts the mic pre-amp in the loop – see Post #5.

Regards, 
Wayne


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## somm (Feb 19, 2012)

jtalden said:


> Possibly there is feedback from the input to the output due to the 6i6 settings? I think the 6i6 mix control interface is setup similar to my Saffire mix control?
> 
> Above I remembered wrong as to how I have my saffire setup. See *Here* to better explain.
> 
> If that is not the problem you will probably need to provide some more information as to the warnings and what your specific setting are.


You are my Hero, I have read your instructions and it works. Thank you.

But I will also,try the TRS to TRS cables.

Somm


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## jtalden (Mar 12, 2009)

Glad I could help!

A TS to TS or a TRS to TRS should give the same result and are fine to use.

The XLR to TRS includes the mic preamp in the calibration and there may be some difference in the low end roll off and thus the calibration file. Since a mic will be used for the measurements the XLR to TRS is the more accurate method. Just be sure that phantom power is not active when the calibration is done and also be aware that with the mic preamp in the circuit the input gain adjustment will be much lower so as not to overload the input. We still adjust it the same way so the input and output are similar but the gain knob on the 6i6 will be set pretty low to do that.


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## somm (Feb 19, 2012)

jtalden said:


> Glad I could help!
> 
> A TS to TS or a TRS to TRS should give the same result and are fine to use.
> 
> The XLR to TRS includes the mic preamp in the calibration and there may be some difference in the low end roll off and thus the calibration file. Since a mic will be used for the measurements the XLR to TRS is the more accurate method. Just be sure that phantom power is not active when the calibration is done and also be aware that with the mic preamp in the circuit the input gain adjustment will be much lower so as not to overload the input. We still adjust it the same way so the input and output are similar but the gain knob on the 6i6 will be set pretty low to do that.


With the gain you are right, I had to adjust my also to the left end.

The phantom power was of, and if you mean that using the XLR to TRS is the better way than I think I can start to measure.

Thank's again to all for the help ...


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