Can't calibrate Motu 828 Mk 1 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 20 Old 01-18-09, 10:47 AM Thread Starter
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Can't calibrate Motu 828 Mk 1

Hello room,

I have a Mac Pro Dual 2.8 running 10.5.6, Motu 828 mk1, and I'm doing exactly as the "Choosing audio input and output" states. I connected the R side of the main outs to the Channel 4 input on the Motu 828 line ins. (According to the help guide, it says do not us an input that is also a mic input). Line ins 1 & 2 are Mic/Line inputs. That's why I used line in 4. In the Audio Setup of the MacPro Dual 2.8, I have the Motu 828 set as the default audio device. In REW, my input and output device is set to "default device". The sampling rate is 44.1 KHz, input channel is "right". "Use left channel as calibration reference" is UNCHECKED. When I click "check levels", my output flutters between -11.8 and -12.0 which is fine according to the guide. My inputs however, doesn't exceed -82.1 and thats with the volume control for line in 4 on the MOTU turned all the way up. Please help, somebody. I've completed treating room with bass traps and broadband absorption and would like to know wher I stand with response, RT60, etc. The room sounds good but I wanna see what the stats are of my room.
P.S. Do I have to use the line in and out on the Mac Pro for anything? What am I doing wrong.

Signed, Sitting in front of screen waiting for a reply, help, anything..

Last edited by playitbyearmusic; 01-18-09 at 11:28 AM. Reason: Thought of another question.
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post #2 of 20 Old 01-18-09, 12:25 PM
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Re: Can't calibrate Motu 828 Mk 1

Quote:
In REW, my input and output device is set to "default device".
Try changing it from "default" to "USB Audio" (or the name of the soundcard, if that shows up).

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post #3 of 20 Old 01-18-09, 03:21 PM Thread Starter
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Re: Can't calibrate Motu 828 Mk 1

Thanks for responding, I tried that also. "MOTU 828" appears in the input device drop down but not the output drop down. Still, no luck. However, I did get a level when I connected the R main output to the R Mic/Line input on the MOTU which the guide says do not do. In audio setup, I have the "Monitor input" set to Monitor input 2, (which is the Mic/Line input). Every time I take a reading with this connection, a report is generated that says "Impulse response is not correct. It must be corrupted". What am I doing wrong?

Signed, still in front of the lcd waiting for a solution. Please help!!!
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post #4 of 20 Old 01-18-09, 03:24 PM
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Re: Can't calibrate Motu 828 Mk 1

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I did get a level when I connected the R main output to the R Mic/Line input on the MOTU which the guide says do not do.
Where does it say that?

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post #5 of 20 Old 01-18-09, 04:24 PM Thread Starter
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Re: Can't calibrate Motu 828 Mk 1

I dont exactly remember where but it stated not to use a mic/line input if the input has phantom power. Is it allright to use it? Mic/Line input 1 & 2 seems to be the only inputs I can get a input level on, (of course with phantom power turned off) however, for it to get high enough, I have to turn on "monitor input" from the motu audio setup and then I can use the monitor volume to adjust. I still get the error that says "Impulse response not where it shoud be, it must be corrupted".
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post #6 of 20 Old 01-18-09, 04:42 PM
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Re: Can't calibrate Motu 828 Mk 1

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it stated not to use a mic/line input if the input has phantom power. Is it allright to use it?
It's fine as long as you turn off the phantom power (which is used when the mic is connected).

Quote:
I have to turn on "monitor input"
No, you don't want any monitor mode turned on.

Just connect line-out to line-in and do your soundcard cal. Then remove the loopback and hook up your mic and receiver and do your measurement.

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post #7 of 20 Old 01-18-09, 04:42 PM
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Re: Can't calibrate Motu 828 Mk 1

You can use the Mac Pro Line In and Line Out instead of the Motu, just make sure they are set as the defaults in the Mac preferences before starting up REW. On a more general note, a combined mic/line input is fine in its line setting, it is typical laptop mic inputs which are not suitable.
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post #8 of 20 Old 01-18-09, 04:54 PM Thread Starter
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Re: Can't calibrate Motu 828 Mk 1

If I dont turn on the monitor input, the signal doesn't get high enough.
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post #9 of 20 Old 01-18-09, 05:02 PM Thread Starter
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Re: Can't calibrate Motu 828 Mk 1

You mean to tell me I can just run an 1/8 inch cable from the out of the Mac Pro to the in of the Mac Pro?
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post #10 of 20 Old 01-18-09, 05:05 PM
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Re: Can't calibrate Motu 828 Mk 1

For the loopback cal, yes, for measurement you'll need break outs to connect to your mic preamp and amp.
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