Film-Tech Forum ARCHIVE: Help with volume trouble from optical readers

This is topic Help with volume trouble from optical readers in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=005728

Posted by Jeremy McBride (Member # 2099) on 01-08-2004, 04:55 PM:

I'm relatively new to the projection booth (about 1 year), and I have been rather roughly thrown into the position of chief as our previous projectionist left without much warning. I had a few months of side by side training with him, but of course, I'm still learning everyday. So anyway, on with my question.

On the particular projector in question (Strong Superhighlight II console, Century projector head) I have both a basement optical reader (Century, analog) and a dolby cat. 702 penthouse reader. The problem lies somewhere with the basement reader. Our policy logos do not have a digital track, so the sound reading duties drop down below for the minute or two of policy. When this happens, the volume level drops significantly. Almost muted. Even though it's just the elevator music that you suddenly can't hear, it's not very nice to the guests when the trailer or feature begins and the sound instantly jumps back to normal volume level. So I'm assuming something needs replacement- the light signal is not strong enough to be picked up properly? Any help would be greatly appreciated.

Posted by Ken McFall (Member # 845) on 01-08-2004, 05:18 PM:

All films should be recorded so that the level is subjectivly the same between both formats, SRD and SR.

Have you checked recently the Dolby Tone level adjustment. You don't mettion what processor you are using but many cinemas seem to neglect this routine check. If this level has dropped over time then you will indeed notice the different levels.

If you are using Red Led's for your analogue sound then if you cannot get Dolby Tone level the current may have to be increased slightly to compensate for the age of the LED cluster. Alternativly the sound head may well have become out of line. If you are not sure of any of this then call in your service tech and ask him to check over your system and perform a full 'A' chain alignment for you. This will restore your system to a calibrated condition and should sort out your problem.

One final point to consider is that the Policy Logo has been poorly recorded! When running a feature how does it sound if you switch between SRD and SR. If the levels seem to be the same or very sinilar then its your Policy Logo.... if not then you need an 'A' chain alignment.

Posted by Jeremy McBride (Member # 2099) on 01-08-2004, 05:30 PM:

Our policy are generic crap from some place in nowhereville. But they run fine in our other projectors with identical setups. I actually tried running a dolby test tone through it and it couldn't pick up a signal. The processor is a dolby CP500. And we are using red LEDs. When switching between SRD and SR during the feature, the same problem occurs. I have noticed that occasionally the policy will play fine in SR, maybe once a week.

Posted by Dave Macaulay (Member # 813) on 01-08-2004, 07:52 PM:

Thre are several things that could be causing this, the projector needs an A-chain setup. I suggest you call your technical service supplier; this isn't a task that projectionists normally have the equipment or training to perform.