|
|
Author
|
Topic: Need for delay in surrounds with digital?
|
Frank Angel
Film God
![](http://www.film-tech.com/ubbmembers/248b.jpg)
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
|
posted 02-22-2002 06:16 AM
Dolby analog surround is delayed so that the bleed, especially of dialogue from the front channels is "masked" by the audio illusion of no sound being there if it arrives at your ear slightly later than the front sound (your ear being the spot the tech was standing when he aligned the system -- everywhere else it sucks). The only sound (in theory) that you will hear when the surrounds are delayed properly will be that which is not present in the front channels. But what happens with digital -- or even mag for that matter, where the surround channel are descrete? Logic would dictate that there would then be no need for the delay, except for really large theatres where you need delay just so that the surround audio doesn't arrive at the ear significantly later than the front sound, otherwise you wind up with an echo. I have Eventide delays for the two surround channels with two outputs, one for the orchestra and one for the balcony. Both are set first to make the surround sound arrive at the same time as the front sound, in each of the two distances. Then when aligning the CP50, the Eventides are used to increase the delay for the needed additional lag value from the arrival time of the front channels (as per standard Dolby setup). In this setup the CP is not used to set the delay. So, With DTS, do the settings for the surrounds have to be changed so the delay units DON'T add lag between the front and rear, i.e., the surrounds should be timed so that sounds from the rear arrive at the same time as the front sounds at the mean test point? Does DTS, Dolby (re: SRD) and/or Sony discuss the need (or not) for delay in the surround channels? Hmmm, this doesn't sound like I am explaining it clearly. Anyone understand what I am talking about?
| IP: Logged
|
|
|
|
|
|
John Wilson
Film God
![](http://www.film-tech.com/ubbmembers/269.jpg)
Posts: 5438
From: Sydney, Australia.
Registered: Dec 1999
|
posted 02-23-2002 09:00 PM
GordonYou mean the DTS itself has a delay or relies on the delay of the CP-whatever. John
| IP: Logged
|
|
|
|
Ray Derrick
Master Film Handler
![](http://www.film-tech.com/ubbmembers/1001.jpg)
Posts: 310
From: Sydney, Australia
Registered: Sep 2001
|
posted 02-26-2002 03:36 AM
In theory, Digital requires 10 to 20mS less surround delay than optical but as has already been pointed out, the centre-to-surround crosstalk is not an issue, so the setting is not as critical as it is for optical.The DA20 has adjustable digital surround delay and the setup procedure is described on page 4.3 of the installation manual. With CP500 and 650 there are separate adjustments for optical and digital surround delay although the 650 can automatically calculate the digital delay from the analog setting. DTS has an in-built fixed delay of 50mS (which as Karen has stated is on the discs, not in the player). If you have a big theatre and need more, then with most analog processors you have to add it externally. SDDS DFP-D3000 uses the same setting for both optical and digital surround delay. ------------------ Ray Derrick President/Chief Engineer Panalogic Corporation Sydney, Australia Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935
| IP: Logged
|
|
|
All times are Central (GMT -6:00)
|
|
Powered by Infopop Corporation
UBB.classicTM
6.3.1.2
The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion
and agrees to release the authors from any and all liability.
|