Film-Tech Forum ARCHIVE: SRD Reader Calibration with QC10 test loop

This is topic SRD Reader Calibration with QC10 test loop in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jean-Michel Grin (Member # 1360) on 03-31-2007, 06:02 AM:

Hi everybody

Recently I made an adjustement of a dolby digital basement reader on a christie projector, using a scope, a latop PC running the windras software an a Dolby QC10 film test loop.
This film test loop, an fact is a Dolby Tone Cat 69 with the analog and digital soundtrack and this test film have been checked by dolby labs to indicate how precise is the "picture" of the digital sound track.
Theses results are wrote on the film test loop: For example You can find: Azimuth: -2 Lateral: +0.92 Vertical: 1.42 Serial Nr: xxxx
My question is: How I have to adjust the reader to perfect match the digital track ?
If the indication of lateral marked on the test Loop is +0.92, should I adjust the position of the reader to read 0.92 on the Windrass Software ? Or should I adjust to obtain "0" or +1.84 ?
The same question is for azimuth angle: if it's reported on the test Loop: Azimuth -2, shoul I read Azimuth -2 on the Windrass software ?
If someone have any idea, this will be appreciated.

Thanks You, and appologyses for my weak English :-)

Jean-Michel GRIN

Posted by Louis Bornwasser (Member # 3063) on 03-31-2007, 06:38 AM:

Your English is fine enough.

It is not necessary to exactly match settings on Dolby Digital. The QC10 is for setting up quality control at studios. It is however necessary for the acceptance wi ndow to not be too far off.

WE do set up without a film using only a scope. Visually, you can get very close. Never have we had a problem getting proper operation when the test loop is applied. Then smaller adjustments, typically lateral film placement, are made.

The processor has very good error correction. If your scope trace is acceptable, then you should be all set even with small differences. Louis

Posted by Steve Guttag (Member # 268) on 03-31-2007, 07:32 AM:

For good reader set up both a scope and dras are indeed necessary.

The Scope will tell you what you really need to know about focus and level and to some degree lateral placement. Dras is best for setting azimuth and final lateral postion, if you indeed have calibrated/measured test film.

We buy our film in 1000' lengths so that we have a uniform roll and measure it against a reference so we know what the offset is for that roll. Thus all of our D-Tone/P-Noise is now "calibrated."

If you get your azimuth dead on (and lateral position) then you will be in the middle of the range and are more likely to be able to play even marginal tracks. Azimuth is more critical than lateral postion. Lateral position only really bites you when you get near the limits (like falling off a cliff...you are okay until that last step). Azimuth has a much more restrictive limit so it is best to get that close to the mark. If one does not have calibrated film...use several trailers/features to see if there is an average that can be used...normally that will work for you...the more you use in the average, the better overall average you will have.

As to how to adjust the readers...that can vary based upon the reader. Kelmar has a ver elaborate system with lock screws and adjustment screws. Component Engineering is more straight forward...setting focus and azimuth with a CE reader is just like setting it with the analog reader. Kinoton is also pretty straight forward with screws that will aid in setting azimuth.

Lateral position almost always involves moving the reader board relative to the lens...again different basement readers do this differently. However, they all take on the theme of loosening the screws that hold the reader board to its holder an then moving the board either physically or via a set screw...odds are your hands will be involved in moving it in either one or both directions.

Posted by Jean-Michel Grin (Member # 1360) on 04-01-2007, 09:32 AM:

Ok, Thank You for your help and advices.

Best regards.

Jean-Michel