Measuring multichannel with Mac - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 13 Old 05-19-16, 04:16 PM Thread Starter
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Measuring multichannel with Mac

Dear Forum members,
I am using REW 5.15 on a Mac and would like to measure the speakers latency of a 7.1 system. Currently I am pulling the cables one at a time to make measurements. The reason is that I get only a stereo (2 channels) at best. It takes a long time. Any better option?

My equipment options include:
UMIK-1
EMM8000
SiS USB Sound Card
HDMI connection to MRX 710.

Thank you,

AlleyCat
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post #2 of 13 Old 05-20-16, 06:27 AM
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You'll have to instal a software called soundflower for Mac.
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post #3 of 13 Old 05-20-16, 02:13 PM
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Re: Measuring multichannel with Mac

Or you can create an aggregate device, see this post.
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post #4 of 13 Old 05-21-16, 07:19 AM Thread Starter
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Re: Measuring multichannel with Mac

JohnM,
Thank you for the link.

Is it possible to measure reliably with REW 5.15 the System Delay for each speaker, using HDMI multichannel (as described above) and a Umik-1?
Or
HDMI and EMC8000 with Focusrite Scarlett 2i2 USB Audio Interface?

Thank for any information or links with respect to my question.

AlleyCat
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post #5 of 13 Old 05-21-16, 12:22 PM
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Re: Measuring multichannel with Mac

Yes, you could measure system delay for each channel using either UMIK-1 or ECM8000. For UMIK-1 you would use REW's acoustic timing reference and make sure the reference channel was one of the two channels selected for the aggregate device. For ECM8000 you could use acoustic reference or a loopback connection.
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post #6 of 13 Old 05-23-16, 10:47 AM Thread Starter
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Re: Measuring multichannel with Mac

JohnM,
Thank you for pointing me to the information about testing 8 channels using HDMI Aggregate interface. After trial and error I got the system to use different channels, but slightly different from the instruction on the post. I got it working with Multichannel option selecting a stereo (2 channels) only.

With respect to using loopback connection for measuring System Delay. I could not get it working using the Aggregate Device for Output and SiS (USB) for input. Any workaround that would allow me to send the signal via HDMI on the Right channel, and mixing the signal with the SiS Out Right, so I can loopback to SiS Input Right?

I am trying to describe the issue and I am not sure I am clear. I want to use the Loopback on my SiS to detect System Delays, and send the signal via HDMI to 8 (actually 7) channels.

My next step is to find a method to quickly measure Dolby Atmos, or 11 channels. Any idea about ways to measure quickly by controlling the input signal?


Thank you,
AlleyCat

Last edited by AlleyCat; 05-23-16 at 10:55 AM.
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post #7 of 13 Old 05-23-16, 01:51 PM
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Re: Measuring multichannel with Mac

Do you specifically need to measure latency from the computer? If not, you could use the acoustic timing reference to measure delays relative to one of the HDMI channels. Don't know about measuring Atmos, but you could always resort to the old faithful tape measure.
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post #8 of 13 Old 05-24-16, 10:32 AM Thread Starter
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Re: Measuring multichannel with Mac

Hi JohnM
I am getting wrong measurements for System Delay.

Here is my Preferences and Measurement information.

Any suggestion on how to fix this?

Thanks,
AlleyCat
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Measuring multichannel with Mac-screen-shot-2016-05-24-11.26.54-am.png  

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post #9 of 13 Old 05-24-16, 02:37 PM
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Re: Measuring multichannel with Mac

From the image it looks like you made a measurement of "Both" using the left as a reference, so both the left and whatever as on the right would be playing at the same time. It isn't very meaningful to measure delay with more than one speaker playing.
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post #10 of 13 Old 07-29-16, 02:44 PM
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Re: Measuring multichannel with Mac

Still willing to pay someone to get me up and running with REW on a Mac. I have the minDSP mic and am running Mac OS X El Capitan. Walk me through it over the phone where you have a mac and i have mine. This is the most frustrating thing to not be able to get this running and I really need to use it.

Please PM if you can help!!


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