Film-Tech Forum ARCHIVE: Dolby Digital brackets

This is topic Dolby Digital brackets in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Sigurd Wik (Member # 6131) on 05-12-2016, 12:34 PM:

Hi,

Do any of you have drawings of the metal brackets that connects a Dolby Digital Cat.700 sound head to a DP70?

Sigurd

Posted by Mark Gulbrandsen (Member # 72) on 05-12-2016, 01:49 PM:

I can picture it in my head but honestly, the factory bracket left a lot to be desired. You are really better off making a plate and sandwiching it between the upper magazine and the projector. 1/4" alumnium works nicely.

Mark

Posted by Stephan Shelley (Member # 8587) on 05-12-2016, 03:03 PM:

It is just a metal plate that has 3 countersunk holes to bolt to the top of the DP70 and two threaded holes that match up to the slots in the bottom of the CAT 700.

Posted by Sigurd Wik (Member # 6131) on 05-13-2016, 12:19 PM:

Thank you guys, that's what I'll do then.

Sigurd

Posted by Mark Gulbrandsen (Member # 72) on 05-13-2016, 12:56 PM:

I recommend to slightly slot those holes so you can use metal film to get things perfectly aligned. The alumnium lateral rollers on Dolbly scanners tend to wear quickly on one side if they are out of alignment by even a smidgen... If you have a BACP Penthouse reader available that is a better choice.

Mark

Posted by Stephan Shelley (Member # 8587) on 05-13-2016, 09:44 PM:

A little more info. It is made from 1/2 plate. 5 inches front to back and 4 5/8 inches side to side with the firs 1 inch on the operating side milled 1/4 inch on the under side so it steps up to follow the casting on the top of the projector.

Posted by Sigurd Wik (Member # 6131) on 05-10-2017, 10:54 AM:

I haven't gotten around to doing the installation of cat. 700 readers on a couple of DP70s, so I'm picking up this thread again. Couple of questions: Seems to me that the only way to do this is to cut off the fire gate on top of the projector, right? And as far as I can see the readers should be fastened to the projector in front of the top reel house, right? We are screening change over with original DP70 reels, so it would need to go pretty far in front to avoid touching the quite big reels.

Sigurd

Posted by Sascha F. Roll (Member # 9043) on 05-10-2017, 11:58 AM:

Maybe you would be better of with 2 of the Kinoton Reverse Scan Analog/Digital readers?

There should still be some of them around...

Posted by Sigurd Wik (Member # 6131) on 05-10-2017, 04:59 PM:

Thanks. Yes, that would be great. I'm on a tight budget on this though, and I have two cat. 700s laying around. Might also have to modify the Kinoton, as I need to be able to run both red and white light for analog reading of cyan and non cyan tracks.

Sigurd

Posted by Mark Gulbrandsen (Member # 72) on 05-10-2017, 06:06 PM:

I tried using one of those Kinoton readers once. They are very lightly built but work ok. The part that REALLY sucks is it is a big job to re-led one.

I still prefer the BACP penthouse reader the best, The DTS timecode reader mounted inboard, and the original Phillips soundhead with the BACP Reverse scan conversion done to it.

Posted by Stephan Shelley (Member # 8587) on 05-10-2017, 06:08 PM:

Generally speaking the visible red works well for all.Pacific Film Archive in Berkeley has done a lot of test with different types and not had issues with the red readers they have.

Posted by Sigurd Wik (Member # 6131) on 05-11-2017, 06:13 AM:

Thanks for nice pictures, Mark.

Back when red light was implemented there was a lot of debate regarding red light reading on all prints, so I decided to do my own tests. I found similar things that Steve Guttag posted here in another thread, that quite a lot of older color prints sound very harsh. As we screen a lot of archival prints, this was unacceptable. I made recordings of it all, can find them if anyone is interested.

Also, once I was surprised to receive a print with a red sound track. Would have been interesting to screen that with red light.

Sigurd

Posted by Steve Guttag (Member # 268) on 05-11-2017, 06:57 AM:

quote: Stephan Shelley
Generally speaking the visible red works well for all.

Generally speaking, that is an incorrect statement. Crossmod distortion with red readers on conventional soundtracks are WELL documented and easily demonstrated, even without test equipment. The degree of audible distortion varies by density of the soundtrack so it is not a uniform thing from one movie to the next. Kodak has a good paper on it https://www.kodak.com/KodakGCG/uploadedfiles/motion/US_plugins_acrobat_en_motion_support_h44_h44.pdf

High-magenta tracks that only have a magenta layer prior to application were designed to work equally well (but not as well as magenta + cyan + application for white light or IR light) on red or white light readers.

So, when you conduct your tests, if you want to see what cross mod distortion can sound like, ensure that you are using the tracks that would show off the problem. Again, this isn't a theory but a very proven fact.