Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 738 - AVS Forum | Home Theater Discussions And Reviews
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post #22111 of 22115 Old Today, 01:46 PM
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Hi guys -

I was making some adjustments to my miniDSP after moving one of my subwoofers and ran into some unexpected results with REW. Here's what I did:

I setup REW with a timing reference (using the center speaker) and ran a frequency sweep
I then ran sweeps with the same center speaker as a timing reference for the front and rear subwoofers, intending to use the delay differences in my miniDSP setup.

Oddly - my initial sweep went wrong somehow: showing a delay of 7.5ms for the center speaker using the center speaker as a timing reference. That obviously doesn't make any sense. Any insight as to why this happened? I re-ran the test with the sweep running from 80Hz to 300hz (eliminating the subs) and ensured my receiver was set to pass the signal directly through.

Thanks,
Mike

PJ - Sony VPLHW45ES / Screen - EliteScreens 120" CineGrey / BD - Sony BDP-S5100 / AVR - Yamaha RX-A3030
Speakers - B&W 683S2/ HTM61S2 / 685 Surrounds / Fluance Signature Bi-polar Rear Surrounds/ PSA S1500 & XS15se subs
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post #22112 of 22115 Old Today, 01:48 PM
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Quote:
Originally Posted by mjmcmahon67 View Post
Hi guys -

I was making some adjustments to my miniDSP after moving one of my subwoofers and ran into some unexpected results with REW. Here's what I did:

I setup REW with a timing reference (using the center speaker) and ran a frequency sweep
I then ran sweeps with the same center speaker as a timing reference for the front and rear subwoofers, intending to use the delay differences in my miniDSP setup.

Oddly - my initial sweep went wrong somehow: showing a delay of 7.5ms for the center speaker using the center speaker as a timing reference. That obviously doesn't make any sense. Any insight as to why this happened? I re-ran the test with the sweep running from 80Hz to 300hz (eliminating the subs) and ensured my receiver was set to pass the signal directly through.

Thanks,
Mike
Post .mdat.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
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post #22113 of 22115 Old Today, 01:56 PM
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I'd dumped the originals, but here's another test with the same issue - speaker 1 1 (Left Front) used as timing reference, yet shows a system delay??

zip file attached
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File Type: zip Timing reference issue.zip (191.6 KB, 5 views)

PJ - Sony VPLHW45ES / Screen - EliteScreens 120" CineGrey / BD - Sony BDP-S5100 / AVR - Yamaha RX-A3030
Speakers - B&W 683S2/ HTM61S2 / 685 Surrounds / Fluance Signature Bi-polar Rear Surrounds/ PSA S1500 & XS15se subs
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post #22114 of 22115 Old Today, 02:21 PM
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OK, what are we looking at here? Hint: label your measurements if you expect feedback.
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post #22115 of 22115 Old Today, 03:30 PM
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Quote:
Originally Posted by AustinJerry View Post
OK, what are we looking at here? Hint: label your measurements if you expect feedback.
Sorry Jerry - I thought I'd explained it thoroughly but obviously not. The first measurement is the reference timing - in this case the Front Left speaker. The second is the subwoofer using the front left as a timing reference. I was following the instructions provided here for measuring time delay - https://www.minidsp.com/applications...ing-time-delay

Under the section "Tabulate your results", it points out that you should have a zero System Delay for the first speaker - which would make sense when you're measuring the same speaker as you use for a time reference. In my case, the system delay showed 6.92ms for a system delay on the same speaker?

I've updated the .zip file with labels to help clarify things.

Thank you,

Mike
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File Type: zip Timing reference issue.zip (192.1 KB, 1 views)

PJ - Sony VPLHW45ES / Screen - EliteScreens 120" CineGrey / BD - Sony BDP-S5100 / AVR - Yamaha RX-A3030
Speakers - B&W 683S2/ HTM61S2 / 685 Surrounds / Fluance Signature Bi-polar Rear Surrounds/ PSA S1500 & XS15se subs
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