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Author Topic: Threading Sound Heads (Spin-Off) Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 12-19-2003 02:52 PM                     Spinning off from THIS TOPIC quote: Kevin Wale asked: Is the amount of tension on the film around the sound drum what you are varying to move the sync around or is it in the processor that you're doing that? What I do is make the lower (holdback sprocket) loop larger or smaller, thus decreasing or increasing the amount of film between the picture aperture and the scanning point of the sound head. Assume you are working on a Simplex projector with 5-Star sound head as I am. (Others are similar. I just demonstrate on the equipment I am familiar with.) First, because of the design of this projector/sound head combination, you have the ability to gather/release some slack in the film between the projector and sound head: Simply move the film on the sprocket by one or two holes to enlarge/shrink the loop. On my sound head I have made reference marks for threading the spring loaded idler roller: When the silver bracket that holds the roller is between the white marks the film is threaded with the proper sound advance. The lip-sync is "Dead-Nuts" on for the greatest number of customers in my theater. (As determined by experimentation on my part.) If I want to vary the sound advance by one or two sprocket holes I can simply let an extra sprocket's worth of film go off the projector sprocket. This will make the lower loop smaller. That much less film will be between the picture aperture and the sound scanning point and the sound will come out of the speakers that much sooner. (About 0.1 seconds in my estimation.) When this is done, the spring loaded idler roller will move backward thusly: I call this "Threading Early". If I wanted to go the other way, I could gather up an extra sprocket hole's worth of slack to make the lower loop larger and cause the sound to come out of the speakers that much later. The idler roller would look like this: I call this "Threading Late". I don't know why somebody would want to do this on purpose unless it was for demonstration purposes only. I have the white marks on my projector because most of my workers are Work Study students who don't have a whole lot of experience. I teach them a set method of threading the projector and forming the upper/lower loops. They are told to stick to that procedure. IF they do things correctly and IF the idler roller bracket comes out between the two white marks when they are done, they have threaded correctly. The sound advance will be right for my theater. Once this point is reached it's an easy matter to alter the advance for a given purpose. If I want to demonstrate to a trainee the importance of threading the projector correctly so the lip-sync is right or if I just want to make the lip-sync correct for my own seating position I can. Sometimes It drives me nuts to have to watch a film that's just a hair out of sync.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 12-19-2003 03:29 PM                     Out of curiosity, why so much emphasis on the tensioner? It really makes no difference where that is in regards to the sound sync. The only thing that affects that is the lower loop size. While I'm sure you know this, it seems all of this discussion on the tensioner is only going to confuse newbies trying to learn.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 12-19-2003 03:31 PM                        Again, the actual separation between the picture frame and the corresponding modulation on the analog soundtrack is 21 frames, per standard SMPTE 41-1999 --- threading here would put the sound in sync right at the screen speakers, and would be appropriate for a very small theatre/screening room, or a drive-in with in-car sound. For most theatres, you want the sound to lead the picture by about 1 frame (1/24 second), because it takes about that long to reach a seat 50 feet from the screen. So most theatres should thread with a 20 frame offset, which usually are the markings on the head leader.  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 12-19-2003 03:49 PM                  I was confused by that as well... I can see how that would vary the wrap tension on the drum and possibly change the time by a few microseconds... perhaps this is the "hair out of sync" you refer to in your post. What's the story, Randy? >>> Phil  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 12-19-2003 04:10 PM                     Yes, I understand what you're saying. But everything depends on threading the projector correctly the first time. Then, by taking up and extra hole's worth of the film (or letting off and extra hole's worth) the sound advance can be adjusted. The marks are simply an indicator. When I train, I teach my students to make the lower loop a certain size by using a set landmark in the projector. (NOT by using two fingers!) Then I tell them to tension the film in the sound head so that the silver bracket is between the two marks. If done this way, it will be right for my theater. For the time being I tell them no more so as not to confuse them. (Just as you pointed out.) I have a piece of leader marked with a STAR and an "X" to check their threading. (The STAR goes in the aperture. The "X" should line up with the scanning point of the sound head.) I give people one sprocket hole's with of leeway in either direction and still consider the job done right. When I check their work before letting them roll the film I have the option to adjust the film as mentioned above. At first I find some mistakes but after they get used to it they get it right-on 90% of the time or better. Once a trainee proves himself to be proficient at threading I start teaching him/her more of the finer points... "If you want to vary the lip-sync, do this..." (The above technique.) I put forth my technique here mainly to answer the question. For most people here, I would imagine something like this is intuitive. In my world I have to do things from an academic perspective. I don't have to "produce" movies on a commercial scale but, on the other hand, my customers are from the college community. Some of them, being the college professor types, do analyze things like lip-sync and I DO get comments on it. My way of doing things, hopefully, blends into the academic nature of my surroundings. I teach in "Levels" for lack of a better way to put it. I have Freshmen (or First-Year Students, for those that didn't join when they were Freshmen) who know the basics. They can thread/run the projector and splice film. My Sophomore (Second-Year) students do the breakdowns and supervise the Freshmen in my absence. (Part of the upperclassmen's training is in how to supervise the underclassmen.) My Second-Year guy knows about things like adjusting the film advance. I don't have any Junior/Third-Year students yet. I've only been in charge here for two years. I'll develop a Third-Year training level when the time comes.  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 12-19-2003 04:44 PM                  Ohhhh.... I misread your original post. You leave the film at the soundhead sprocket where it is and move the film at the ***projector*** holdback. You only use the tensioner position as the "indicator". Got it... Duh! >>> Phil  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 12-19-2003 04:51 PM                     Do you run platters or reels? The 5-star sound head should have between 1 and 2 perforations of slack...that is it (slack being defined with the soundhead damper roller not contacting its right-hand stop pin and not in any way lifting the pinch roller). It looks like your marks put you there are perhaps a perforation or so loose. On the 5-star, if you thread the damper too loose you may not be flutter free at changeover. It is a function of the damper spring forcing the drum up to speed and the damping fluid doing its job on slowing down the damper roller pivoting. Steve  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 12-19-2003 10:18 PM                     It's platter. Yes, it's one sprocket hole too loose. For platters it's not much of an issue. Instead of me trying to explain myself in 1,000 of detail, why don't I just say it like it is: You're supposed to thread with 21 frames advance but if I did that only the people in the front would hear in sync so I thread with 20. Most of the customers hear the film correctly that way. If I'm watching alone I thread on 19-1/2 because I'm sitting at the extreme rear of the balcony. If I want to change the threading from 20 to 19-1/2 I just lift the pad roller from the projector sprocket then let off two sprockets worth of film. If I want to make the advance "later" I lift the sprocket and take back those two sprockets of film. If the projector was threaded with the correct advance in the first place (it will be because that's the way I teach the students) looking at the silver bracket will tell you whether you're "early" or "late". Yes, it takes longer for the sound head to stabilize when the tension roller is off but I don't think that's a big issue in my case. Did I explain it better that time?  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 12-19-2003 10:45 PM                  No... >>> Phil  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-19-2003 11:40 PM                     What I teach every one is thread with the frame marked PICTURE START accross the apperture then postition the sync diamond across the reader. The rest of the film you use up in the loop The correct ensioning on the scanner is very important to prevent flutter especially during startup and at splices  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 12-20-2003 12:14 AM                     I don't often have nice leaders like that on my films. I use the regular, old blue framing leader. I do use a piece of leader marked in Sharpie with the correct settings on it as a teaching aid but when I teach people to thread a certain way, after a little practice, they don't need the marks. It's easy to get the hang of it after a short time. I've been running the projector for quite a while with the tension roller in the position shown in the pictures. I can't hear any changes, jumps or warbles in the sound unless the splice is bad in the first place. For a long time I was the only one running the projector. I was originally hired as a projectionist. After a while I took on duties on the stage, in general. Now, I'm in charge of the stage and the projector. During these times I have had a lot of opportunity to experiment with how it runs. I have threaded it in several different ways and have found what I think is a good setting. In my experience, as long as the tension roller is roughly in the right hand half of its travel there will be no problem. When I was doing things by myself I didn't have the marks like you see in the pictures. I just "knew" how to thread the thing. It was only after I had students working for me that I developed this. I found that I had to have a very specific method to thread with. A problem with my situation is that I only have one or two days a week to work with students. The rest of the time they are studying and socializing. What you guys can teach a new recruit in two days can take me two months to teach, depending on the person. The repetition isn't there. When I teach threading I don't let on what I've been saying here. They learn the general theory of how it works and how to do things so that the sound comes out right. When they learn that I give them some of the finer points. Only a couple of them know that there's room to adjust the film like that. The rest of them have to rethread the whole thing (from the loop to the sound head) if they get it wrong. I don't even make this adjustment myself a lot. Only when I'm sitting at the extreme rear of the balcony myself and want the sound to sync differently for my position.  |  IP: Logged Kevin Wale Expert Film Handler Posts: 167 From: Guymon, OK USA Registered: Aug 2003 posted 12-20-2003 12:46 AM                     Ok, I'm following(I'm familiar with the 5 stars so I'm also following the tensioner reference talk). What I'm not sure of now is how to vary this with a Century Model C. That's what we have at the theatre I now work at and as some of you probably know full well, the holdback loop as it goes over the sprocket and down into the soundhead, it goes right around a post. It seems to me that with that equipment, if I were to thread early(or for that matter, any different than I am now) the film would drag accross that post as it goes to the sound drum. In fact I have seen someone thread up this way. Anyone have the correct loop sizes for that projector with super simplex sound heads? I think my problem is that I was shown when initially trained, how to thread what we had. Not so much shown why the loop sizes were what they were throughout. Now that I'm using equipment that is a bit foriegn to me, I'm kind of in experiment mode to actually find what the best loop sizes should be. When I was being shown the equipment here, I noticed that the projectionists here were making HUGE loops throughout the whole thing. I was like... man that's gonna scratch the film as it flaps on the wall of the soundead there. I'll do a run through after the shows are done tomorrow with a trailer build up and see if I can find the sweet spot for that loop. We're also using the blue leader. Unnumbered leader at that. Just blue windows. All this has me thinking... it would be really cool if there were projection workshops. Maybe three or four day workshops that are progressive. If you've been the last time, your workshop agendas would be different this time. All aimed for people who find they've been trained and yet realize they weren't really trained on the whys, just the hows. I know I really feel that. Surely there are others besides me that want to do it right and want to learn more than they know but aren't surrounded by people that can really teach them.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 12-20-2003 07:52 AM                     If you have a century 35mm projector and soundhead the correct size for the loops is when the machine is in the centre of the pull down cycle the film just touchs the open padroller arm The tension in all soundheads is very criticle as that is part of the principle of the Davis Tight Loop  |  IP: Logged William Hooper Phenomenal Film Handler Posts: 1879 From: Mobile, AL USA Registered: Jun 99 posted 12-22-2003 12:08 AM                        I think Randy's running a big house & pulling an extra sprocket hole out of the loop.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 12-22-2003 12:45 AM                     This entire discussion is enthralling and all, but until the day comes that the labs start printing the analog audio precisely in advanced sync with the image, such efforts to gain or lose a sprocket hole or two is more or less a waste of time except in extremely large auditoriums. Next time you are putting together a film, find a reel change with a lot of analog activity. Line up the end of that reel with the first of the next reel (lay them side by side, don't cut the leaders yet) and find the matching waveforms. You will find that in over 90% of the time, the analog audio has a different offset for every reel.  |  IP: Logged

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