Calibration Trouble.

[Charles Pickrel]

Greetings,
I just installed a new Universal Audio Apollo Twin Thunderbolt audio interface to my 2015 MacBook Pro. I started with a calibration measurement, and I don't like the looks of it. Has anyone seen this before? What might I be doing wrong? The R channel output is looped back to the R input on the Apollo. It doesn't seem to matter whether I use a timing reference on the left channel. Delay compensation is disabled in the Apollo Control app.

Oddly, I get what I expect when outputting from the MVBP BuiltIn output, into the Apollo input.

Any input would be welcome.

Charlie

 

[John Mulcahy]

Looks like a small level of monitoring feedback on the Apollo. Monitoring needs to be completely off.

 

[Charles Pickrel]

John,

Thanks, that was quick. The Apollo Control is new to me, so I will get this sorted. Of course when I mute the Monitor, I get no output from Line 1 or 2. The Mac Audio-Midi Setup, Configure Speakers, assigns input and output channels. There are several alternative Configurations, such as "Stereo," ""2.0 Surround" (used by Safari), "5.1 Surround." I am guessing REW uses "5.1 Surround" ?

Charlie

 

[Charles Pickrel]

On second thought, it would not be "5.1 Surround, because I see 8 channels listed in the REW Set Output Channel Mapping menu (Soundcard Preferences) - which is the same number presented to Core Audio by the Apollo (I assume, looking in the Settings-I/O Matrix output list).

 

[Charles Pickrel]

I don't fully understand where the monitoring feedback may occur, but I got a much improved calibration by setting Apollo Control to assure signals were not mixed to both R and Left channels anywhere, but perhaps more importantly to use the Line 4 output and the Analog R input (sorry the scale is expanded from previous post):

 

[John Mulcahy]

Looks good. The interface is plenty flat enough not to need a cal file, as might be expected, but one of the aims of the cal process is to catch inadvertent monitoring so it served its purpose

 

[Charles Pickrel]

John, I agree - making measurements, one must always be able to recognize a "right answer". Thank you for the help.

Charlie