Film-Tech Forum ARCHIVE: Surround delay time calculation

This is topic Surround delay time calculation in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Daveston Ahimaz (Member # 6288) on 06-05-2011, 02:20 AM:

How to calculate the time delay for the surround speakers in a dolby EX theatre?

Posted by Dominic Espinosa (Member # 2122) on 06-14-2011, 05:29 PM:

Sit in the middle of the room and see how poorly out of synch it is with a test reel/loop/dcp.
Or else RTFM?

Posted by Richard Hamilton (Member # 321) on 06-14-2011, 07:28 PM:

what processor?

Posted by Harold Hallikainen (Member # 5405) on 06-16-2011, 10:46 PM:

Since there has not been a whole lot of response, I'll give an opinion. Since surround speakers in a 5.1 system typically extend partway along the back wall (an L shaped array), it seems that the delay for rear wall surround speakers will be about the same as for the surround speakers. The distance from the screen speakers is not significantly different. The formula I have for surround delays (from the USL JSD-100 manual at http://www.uslinc.com/images/products/download/Jsd100Manual0111.pdf ) is:

The surround delay is set based on the length and width of the auditorium. Formulas to determine the surround delay with
auditorium Length and Width in meters and feet are provided.

Surround Delay Using Meters.
With Length and Width of the auditorium in meters, the surround
delay, in ms, should be (L/3)‐(W/6)+20.

Surround Delay Using Feet.
With Length and Width of the auditorium in feet, the surround delay, in ms, should be set to L‐(W/2)+20.

I look forward to hearing any other opinions.

Thanks!

Harold

Posted by Daveston Ahimaz (Member # 6288) on 07-15-2011, 11:23 PM:

Thank you Harold. I will try what you have suggested.

Richard i am using the Sound web London BLU-160 4 units linked with the blu link.