Our dolby digital error correction reading on the 7seg display usually ranges between 3-7, and occasionally drops out. It varies greatly from print to print.

We are a student cinema, so most of the films we get have usually "done the rounds", (and hence the digital track may be damaged) but all of our trailers are brand new, and sometimes we have brand new prints, but I've never seen it read less than 3. Does this mean there is something wrong with it?

I've seen from previous discussions that any reading 0-7 results in complete reproduction, as it means that the error correction has been successful. However, it must be safer to have the system running at 0-3 rather than 5-7.

Our reader is mounted at the top and is approximately 3 years old from new.

It would be useful to know some sort of average value that people tend to get.

exactly.

The SR-D information is located in a high wear area of the film and is known to degrade, some types of projector "hurt" the sprocket area more than others but a worn or defective machine can destroy the SR-D and SDDS info in very few passes. Analog sound is in a safer film area and isn't usually damaged by a projector but degrades with dirt and handling-related scratches. DTS data is at the edge of a wear area but the data is only low bit rate timecode - much harder to make unusable than the very dense data image of SR-D or SDDS. (DTS would seem to be the ideal digital format for rep houses - but the damn disks are rarely with the prints rep houses end up with. Is there a solution to that?)

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Funny thing was that the first time I ever got numbers that good was right after replacing the LED (2nd time in the space of about a year) as the culmnation of replacing a lot of components trying to locate the source of unstable film motion that was giving me middling numbers (4-5-6) with frequent interspersed F flashes on that machine.

The main culprit there was the sound drum but I didn't get the good numbers til I re-replaced the LED which was very uneven on the scope, despite position adjustments. After I changed it I began by adjusting the position that gave me normal analog Dolby level (on Kelmar the positions are not independent). Then before even looking at the scope or running DRAS I put up an SR-D reel and there I was at 0's and 1's. Turned out it was an exceptionally good print and normally, even with full tweaking, I'm in the 2-3 area but that's decent for a basement reader on a 5-Star.

1) Be sure to order the film in DTS.
2) If no discs arrive, call the film distribuator and request them.
3) If you get no where with the distribuator, contact me and I'll help you. But always try the distribuator first because we always have to get permission (the discs belong to them, not DTS) before sending discs to theaters.

You'll need an oscilloscope, an laptop running DRAS, the appropriate tools and some loops made from known good trailers printed at Deluxe Hollywood.

To obtain a good reference loop, here is what I do. I assemble half a dozen brand new trailers (all from Deluxe Hollywood) and run them. I watch the DRAS and make notes of each one and then use the one on the roll that is the most *average/centered* of them all. At that point, I label it and can make tons more Dolby loops from that one trailer to align with as I need them.

I've found using the actual loops produced by Dolby to align an SRD head is a bad idea. The alignment is never as good as it could be. Also, for some reason when I use loops produced at Technicolor or Deluxe Toronto I end up with high error readings when I play prints out of Deluxe Hollywood. Using Deluxe Hollywood prints to align by, everything plays nicely. Why? No idea. (Don't know, don't care, it works, I get zeros and that's good enough for me! )

Instructions on how to perform the alignment are in the manuals.

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