Film-Tech Forum ARCHIVE: Srd-Sr, Sound Question

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Posted by John Rizzo (Member # 1289) on 11-27-2005, 07:27 PM:

Hi
Last Nite a feature film my lab worked on was shown for the first time. It was at Linclon Center.The print had both sr and srd sound tracks. Earlier in the day they had a test screening, after the test screening the producer called me to tell me that on two of the reels the srd was not right on reels 1 and 3 and that the projectionest said he would use the sr track for those reels. I went to the premire screening last nite and the sound was fine up until reel 6 came on and during that reel there was at least 5 sound dropouts each lasting a couple of seconds. After the movie was finished the producer told me that during the test screening reel 6 played fine. My question is: When you play a film in srd and something goes wrong with the srd track isn't the analog sr track supposed to automaticly kick in, if so how long should that take to happen. Any thoughts or suggustions on this would be greatly appreciated.
Thanks
John Rizzo

Posted by Brad Miller (Member # 2) on 11-27-2005, 08:05 PM:

They may have screened it in a different auditorium. No two SRD readers will track exactly the same.

Yes the Dolby should've instantaneously dropped out to analog.

Assuming the print was screened on the same projector that later was used to run the premiere, odds are there was enough emulsion shedding during that test show to scrape away part of the digital data blocks in the gate due to buildup (which would make sense, as the problem would get worse as more and more film passed through the projector). So their SRD reader could've been barely hanging on during that test screening, but after the one pass there could've been enough damage to cause it to drop out. This assumes of course a penthouse reader.

We really need to know their specific equipment setup to give better answers.

Posted by John Rizzo (Member # 1289) on 11-27-2005, 08:48 PM:

Thanks Brad
I'am pretty sure it was the same theater for the test screening, I will confirm that tomorrow.I can also tell you that it was not plattered and was run on two machines.
Is it a given that when you run srd the sr is always on for a back up or can the sr back up be turned off?
Thanks Again
Tomorrow I will have the density on the srd track checked by the sound lab I was told that if is not at the proper density it can also cause problems.

Posted by Brad Miller (Member # 2) on 11-27-2005, 10:57 PM:

Two machines brings about an entirely new set of potential problems.

First, was the left projector running odd numbered reels on the test screening, but even numbered reels on the preview screening? (This goes back to the fact that no two readers will track the same.) Second, reel 6 could've been misthreaded, hence it wouldn't play back on the preview screening. Likewise reels 1 and 3 could've been misthreaded on the test screening. Many potential factors at work here.

Also, some setups permit the exciter/led to be killed. Personally I like this idea for test screening purposes, as it makes it completely obvious if there is a dropout, but for any sort of public showing, the backup should always be ran. Very few setups are wired like that though, and it is safe to assume the backup analog track was always on.

Posted by Frank Angel (Member # 248) on 11-28-2005, 09:53 AM:

Plus, if the SR is properly calibrated, the switch in and out of it should be nearly transparant to the listener with little or no difference in sound quality, and as Brad says, certainly with no obvious "dead air."