This is topic SDDS mounting suggestions in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by John Walsh (Member # 168) on 12-15-2001, 01:41 AM:
After looking at earlier posts, I get the idea that the perferred way to mount an SDDS and DTS reader is with the DTS first, then the SDDS, then on to the projector.But what about these new mounting brackets the SDDS is using now? Still do it the same way?
Posted by Don Sneed (Member # 955) on 12-15-2001, 09:08 AM:
Hey John, I Just install a 9-screen theatre using SDDS DFP-3000, DTS & DA-20 here in Japan, I did not use the new roller/mounting bracket, We install Strong consoles & projectors, I installed the Dolby Cat.# 701 reader on top of the projector, then the SDDS reader without the new roller assy., & the DTS reader....I cannot read Japanese so I don't know what that new roller assy is for, so I left it out of the chain. installed the SDDS reader as I had in the past...it works perfect for me......I installed the Sony DFP-3000 system, 5-screen channels, whooooaaa weee is does sound good....when tune properly...
Posted by John Walsh (Member # 168) on 12-15-2001, 09:56 AM:
Apparently, the new bracket/roller assembly is to reduce film bouncing through the SDDS reader. There must have been some instances of the SDDS reader misreading the track, but we never had any problems ... never even heard of anyone having that problem.But, if the manufacturer says to use some new assembly, (like this SDDS roller) then I do. If it isn't, and there's a problem, the tech support people will ask if it's installed and will "stop" if it's not. You have to prove to them "first" that their way isn't working.
Posted by Dave Macaulay (Member # 813) on 12-15-2001, 09:57 AM:
The Sony roller/mount assembly is just a spacer. When the DFP200R was replaced by the DFP300R Sony simplified the film path, but didn't think about the resulting shortened path length from the read head to the film aperture. Mounted directly to a Simplex or Century, the path is too short to allow sound sync - the minimum frame offset allowed in the DFP3000D/DFP2500D is more than the actual offset. The original fix was to supply a spacer very similar to a Kelmar film cleaner mount (without the mounting!) but recent shipments have the flimsy bracket with the tension roller.
If you permanently mount more than one digital reader, regardless of the order they are installed you have to be absolutely consistent in threading so the offsets are accurate for each format. Either only thread the one you want to use and have a clearly labelled bypass path for those below it or always thread all digital heads. Threading them all is the safest way, considering the abilities of our "booth ushers".
If you put the DTS head on the projecror then the SDDS can go on top of it. Either threaded or unthreaded the DTS reader is large enough to allow sync on the DFP3000R. If you have a DFP2000R then it doesn't matter, you can set it on the projector.
As far as I know there isn't a problem with very long paths, someone else may know if there is (ie if the maximium offset allowed for SDDS (for instance) is less than the real offset if one threads a CAT700 and a DTS reader below it)...
Probably the best answer is to have a basement SR-D reader and a docker on top (or just one other digital format available). No easy way to screw that up.
Posted by John Walsh (Member # 168) on 12-15-2001, 10:25 AM:
Hi, Dave;The impression I got from Sony is the new bracket is for bounce, since they are suggesting for every projector, not just Simplexs or Centurys. Brad suggested (and I agree with him) that the readers should be mounted such that a person must thread all of them. You're right about "booth ushers"; show someone two ways of doing something, and they will invariably choose the wrong way for the situation at hand!
We are not very happy with basement readers (high error rates.) Some projectors/readers are better than others, but we always seem to have the "wrong" combination. We also feel that (for the configuration we like to have) by the time you pay for those docker units, for a little more you could just buy a DTS reader and leave it there.
Posted by Don Sneed (Member # 955) on 12-15-2001, 04:31 PM:
The problem I have in Japan is I can not get the booth people to bypass the reader they are not using, they thead them all, if using only the DTS, the Sony & Dolby reader is also theaded, If using only the Sony Reader, all is theaded, I told them to bypass the DTS when not using until I am blue in the face, so since no one listen to me I set the readers for the time code/lipsync to be theaded using all readers...in the CP-650 houses I have the Cat.701 on top of the projector, the DTS on top of the Dolby reader...in the Sony houses I have the Dolby reader on top of the projector, the SDDS reader on top of the Dolby reader, the DTS on to of the SDDS reader....I never had a problem with the SDDS reader for the DFP-3000, so I do not install the the extra roller assy.....but I will keep them just in case..
Posted by Brad Miller (Member # 2) on 12-15-2001, 08:09 PM:
What is the point of this? It appears that the only real purpose for this new bracket is to eliminate the possibility of any bouncing from the projector (an out of round sprocket shaft or something).As was said above, since the SDDS 3000 series reader can not run directly atop a 35mm projector and run in sync, it's best to just mount the dts reader below it as a spacer (like pictured above). I'm not sure if I like that bracket, for it just seems like more crap to have to thread through. It's also wasting several frames worth of offset for any reader atop the SDDS reader and is also wasting ceiling height, which is frequently a real issue in some booths.
Posted by Gordon McLeod (Member # 33) on 12-15-2001, 08:26 PM:
Don't you mean a "reel" issue in some booths 
Posted by Brad Miller (Member # 2) on 12-15-2001, 08:31 PM:
A "reel" issue? Why yes even more so with platter-less booths! 
Posted by James R. Hammonds, Jr (Member # 673) on 12-15-2001, 09:56 PM:
The new mounting bracket is as I am told to keep more tension between the reader and the projector.
We had one installed this summer on a house that NEVER read SDDS and after it was put on, it reads perfectly.
We also have a house that currently does not play back SDDS, but when tension is placed above or below the reader, it reads fine.
I was told that one of our theatres in California had these placed on all their projectors and have had no problems.
We are expecting to have all of these in place along with a complete refurbishment soon and hopefully we will be taken care of also.
I fell in love with these tension brackets immediately
Posted by John Walsh (Member # 168) on 12-15-2001, 10:37 PM:
I know that DTS likes to have the film wrap around that first silver roller as much as possible, but the configuration pictured doesn't allow (that black DTS roller will hit if it is spun 180deg.)Don; People can be lazy- they will thread the "shortest" way possible! I am a little surprised, though. Are you saying the Japanese projectionists are not threading it correctly? They are usually very detailed-oriented.
We have some projectors on platforms for our stadium-seating auditouriums. (No one wants to pay to increase the overall ceiling height.) So, even though we're not running reels, we could have a height problem if other manufacturers want brackets like the new SDDS one.
Posted by Steve Guttag (Member # 268) on 12-16-2001, 01:39 AM:
I'm willing to wager that James was using Simplex projectors or possibly Christie (large feed sprocket) and that there was a slight speed variation in the projection system (via sprocket shaft or other out of balance or out of round situation).I wish Sony would just forget about the mag-clutch sprocket and use a good ol flywheel on the drum...problems would just vanish.
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by James R. Hammonds, Jr (Member # 673) on 12-16-2001, 01:52 AM:
I hope you wagered alot, Steve cause you would now be a rich man.
Simplex Millenium by the way.
Posted by Karen Hultgren (Member # 395) on 12-17-2001, 12:52 PM:
Hi John,Nice photo!
You *may* run into some problems with SDDS in front of us. *IF* you notice the green light on the DTS reader blinking a lot - it could be be coming from the spring of the SDDS rollers. If you are not having problems, don't worry about it. If you are having problems, you might need to move DTS in front of the SDDS (and it will effect offset=sync).
Karen at DTS
Posted by Brad Miller (Member # 2) on 12-17-2001, 02:55 PM:
Yes indeed Karen isn't kidding about having dts below an SDDS! However just to throw this in, I've had zero problems with a dts reader mounted below a 3000 series SDDS reader. The only problems I've found (and in virtually every instance) is when a 2000 series SDDS reader in mounted atop a dts reader. There are 2 solutions.#1 Leave the dts reader below the SDDS, but do NOT thread through the SDDS, nor even around the front rollers. If the film is bypassed only via the 70mm bypass rollers on the sdds, it will not affect the dts. I dislike this solution because it prevents having a show where both formats can be used (in conjunction with each other or as a backup) and also because it confuses many projectionists as to which reader they should be threading. The dts offset is typically 24 for this mounting on a Christie (and very close for Simplex and Century).
#2 Mount the dts reader above the SDDS like is shown in the picture below. Note: if the dts reader is not turned upside down like this, the damper roller on the SDDS reader will also hurt the dts reader's tracking. The benefit of this setup is that all readers are threaded at all times and the offset isn't "too" much for the dts unit to be unhappy. The dts offset is typically 77 for this mounting on a Christie (and still very close for Simplex and Century).
Posted by John Walsh (Member # 168) on 12-17-2001, 04:25 PM:
Hi Karen; We only just installed this new SDDS brack/roller assembly, but I haven't heard of any problems yet. I going there again tomorrow, so I'll check with the operators. I'd like to try skipping that last SDDS roller (on the new bracket) and going right to the DTS reader. I'd pivot the black DTS roller around 180deg to get a good wrap.I'd like to do it the way Brad has pictured. The new bracket extends the film length so the SDDS minimum delay is no longer a problem. But if I did, threading around that last SDDS roller then positions the film so it wraps very little around the feed sprocket of the Ernemann projector.